Title of Invention	TUNABLE ANTENNAS FOR HANDHELD DEVICES
Abstract	A compact tunable antenna for a handheld electronic device and methods for calibrating and using compact tunable antennas are provided. The antenna can have multiple ports. Each port can have an associated feed and ground. The antenna design can be implemented with a small footprint while covering a large bandwidth. The antenna can have a radiating element formed from a conductive structure such as a patch or helix. The antenna can be shaped to accommodate buttons and other components in the handheld device. The antenna may be connected to a printed circuit board in the handheld device using springs, pogo pins, and other suitable connecting structures. Radio- frequency switches and passive components such as duplexers and diplexers may be used to couple radio- frequency transceiver circuitry to the different feeds of the antenna. Antenna efficiency can be enhanced by avoiding the use of capacitive loading for antenna tuning.

Title of Invention

TUNABLE ANTENNAS FOR HANDHELD DEVICES

Abstract

A compact tunable antenna for a handheld electronic device and methods for calibrating and using compact tunable antennas are provided. The antenna can have multiple ports. Each port can have an associated feed and ground. The antenna design can be implemented with a small footprint while covering a large bandwidth. The antenna can have a radiating element formed from a conductive structure such as a patch or helix. The antenna can be shaped to accommodate buttons and other components in the handheld device. The antenna may be connected to a printed circuit board in the handheld device using springs, pogo pins, and other suitable connecting structures. Radio- frequency switches and passive components such as duplexers and diplexers may be used to couple radio- frequency transceiver circuitry to the different feeds of the antenna. Antenna efficiency can be enhanced by avoiding the use of capacitive loading for antenna tuning.

Full Text	TUNABLE ANTENNAS FOR HANDHELD DEVICES This application claims priority to United States patent application No. 11/516,433, filed september 5, 2006. Background This invention can relate to antennas, and more particularly, to compact tunable antennas used in wireless handheld electronic devices. Wireless handheld devices, such as cellular telephones, contain antennas. As integrated circuit technology advances, handheld devices are shrinking in size. Small antennas are therefore needed. A typical antenna for a handheld device is formed from a metal radiating element. The radiating element may be fabricated by patterning a metal layer on a circuit board substrate or may be formed from a sheet of thin metal using a foil stamping process. These techniques can be used to produce antennas that fit within the tight confines of a compact handheld device. Modern handheld electronic devices often need to function over a number of different communications bands. For example, quad-band cellular telephones that use the popular global system for mobile (GSM) communications standard need to operate at four different frequencies (850 MHz, 900 MHz, 1800 MHz, and 1900 MHz). Although multi-band operation is desirable, it is difficult to design a compact antenna that functions satisfactorily over a wide frequency range. This is because small antennas tend to operate over narrow frequency ranges due to the small dimensions of their radiating elements. Antennas with tunable capacitive loading have been developed in an attempt to address the need for compact multi-band antennas. By varying the amount of capacitive loading that is applied to the radiating element, the resonant frequency of the antenna can be adjusted. This allows an antenna with a relatively narrow frequency range to be tuned sufficiently to cover more than one band. The adjustable capacitive loading that is placed on this type of antenna leads to unwanted power loss. As a result, capacitively-tuned antennas tend to exhibit less-than-optimal efficiencies. It would be desirable to be able to provide ways in which to improve the performance of tunable antennas for handheld electronic devices. Summary In accordance with the present invention, tunable multiport antennas are provided. Handheld devices that use the tunable multiport antennas and methods for calibrating and using the tunable multiport antennas are also provided. A tunable multiport antenna can have a ground terminal and multiple feed terminals. Each feed terminal can be used with the ground terminal to form a separate antenna port. By selecting which antenna port is active at a given time, the antenna's operating frequencies can be tuned. Tunable multiport antennas contain radiating elements. The radiating elements may be formed, for example, by a foil stamping process or by patterning a conductive layer on a substrate such as a printed circuit board or flex circuit. Each radiating element can resonate at a fundamental frequency range. The dimensions of the radiating element may be chosen to align the antenna*s fundamental operating frequency range with at least one communications band. If desired, the radiating element may also be used at one or more harmonic frequency ranges. The radiating element can be coupled to a printed circuit board on which electronic components for a handheld electronic device are mounted. The printed circuit board can contain conductive traces that connect the components to the ground and feed terminals of the antenna. Electrical connecting structures, such as springs and spring-loaded pins, can be used to electrically connect the conductive traces on the printed circuit board to the ground and feeds of the radiating element. Handheld electronic devices can contain radio- frequency transceivers and switching circuitry. The radio-frequency transceivers can have input-output paths that are used to transmit and receive signals associated with different communications bands. The switching circuitry can selectively connects the input-output paths to the ports of the antenna. During operation of a handheld electronic device, control circuitry on the device can direct the switching circuitry to activate a desired one of the antenna ports. By selecting which antenna port is active, the control circuitry can tune the antenna so that one or more of the antenna's operating frequency ranges aligns with one or more desired communications bands. Because the antenna can be tuned, it is not necessary to enlarge the dimensions of the radiating element to broaden the bandwidth of the radiating element's resonant frequencies. This allows the antenna to be implemented with a small footprint. The use of multiple feeds in the radiating element permits tuning without the use of adjustable capacitive loading, which reduces reactive antenna losses and enhances antenna efficiency. Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. Brief Description of the Drawings FIG. 1 is a perspective view of an illustrative circuit board to which a multi-port antenna is mounted in accordance with the present invention. FIG. 2 is a graph in which the return loss of the antenna of FIG. 1 has been plotted as a function of frequency in accordance with the present invention. FIG. 3 is a schematic diagram of an illustrative handheld device containing a tunable antenna in accordance with the present invention. FIGS. 4-14 are diagrams of illustrative antenna radiating elements having multiple feeds that can be selected for timing in accordance with the present invention. FIG. 15 is a side view of an illustrative printed circuit board showing how vias can be used to connect the upper and lower surfaces of the printed circuit board to form a ground plane for an antenna of the type show in FIG. 1 in accordance with the present invention. FIG. 16 is a perspective view of an illustrative portion of a circuit board assembly showing how a radiating element with an integral spring may be used to make contact between to a pad on a printed circuit board of the type shown in FIG. 15 in accordance with the present invention. FIG. 17 is a cross-sectional side view of an illustrative spring-loaded pin that may be used to connect an antenna's radiating element to a circuit board in accordance with the present invention. FIG. 18 is a cross-sectional side view showing use of an illustrative spring-loaded pin that is soldered to a radiating element to make contact with a printed circuit board in accordance with the present invention. FIG. 19 is a cross-sectional side view showing use of an illustrative spring-loaded pin that is soldered to a printed circuit board to make contact with an antenna's radiating element in accordance with the present invention. FIG. 20 is a cross-sectional side view showing use of an illustrative spring to make contact between a radiating element and a printed circuit board in accordance with the present invention. FIG. 21 is a cross-sectional side view showing use of an illustrative spring that is attached to a printed circuit board to make contact with a post of a radiating element formed from flexible circuit board material in accordance with the present invention. FIGS. 22 and 23 are cross-sectional side views showing use of an illustrative floating spring-loaded pin to make contact between a radiating element and a printed circuit board in accordance with the present invention. FIG. 24 is a circuit diagram showing how illustrative switches may be used to selectively connect a radio-frequency (RF) transceiver integrated circuit operating in two frequency bands to two different antenna feeds in accordance with the present invention. FIG. 25 is a graph showing the return loss of an illustrative radiating element versus frequency as the circuitry of FIG. 24 selects between each of two different antenna feeds on the radiating element in accordance with the present invention. FIG. 26 is a circuit diagram showing how illustrative switches may be used to selectively connect a radio-frequency (RF) transceiver integrated circuit operating in three frequency bands to two different antenna feeds in accordance with the present invention. FIG. 27 is a graph showing the return loss of an illustrative radiating element versus frequency as the circuitry of FIG. 26 selects between each of two different antenna feeds on the radiating element in accordance with the present invention. FIG. 28 is a circuit diagram showing how illustrative switches and a passive antenna duplexer may be used to selectively connect a radio-frequency (RF) transceiver integrated circuit operating in three frequency bands to two different antenna feeds in accordance with the present invention. FIG. 29 is a graph showing the return loss of an illustrative radiating element versus frequency as the circuitry of PIG. 28 selects between each of two different antenna feeds on the radiating element in accordance with the present invention. FIG. 30 is a circuit diagram showing how illustrative switches and a passive antenna diplexer may be used to selectively connect a radio-frequency (RF) transceiver integrated circuit operating in three frequency bands to two different antenna feeds in accordance with the present invention. FIG. 31 is a graph showing the return loss of an illustrative radiating element versus frequency as the circuitry of FIG. 30 selects between each of two different antenna feeds on the radiating element in accordance with the present invention. FIG. 32 is a diagram showing how transmitting and receiving subbands may be coupled to an antenna feed using an illustrative switch in accordance with the present invention. FIG. 33 is a diagram showing how transmitting and receiving subbands may be coupled to an antenna feed using an illustrative duplexer in accordance with the present invention. FIG. 34 is a diagram showing how an illustrative RF transceiver integrated circuit with five bands can be selectively connected to two different antenna feeds using switching circuitry made up of two switches in accordance with the present invention. FIG. 35 is a diagram showing the return loss of an illustrative radiating element versus frequency as the circuitry of FIG. 34 selects between each of the two different antenna feeds in accordance with the present invention. FIG. 36 is a diagram showing how an illustrative RF transceiver integrated circuit with four bands can be selectively connected to two different antenna feeds using two diplexers in accordance with the present invention. FIG. 37 is a diagram showing the return loss of an illustrative radiating element versus frequency as the switching circuitry of FIG. 36 selects between each of the two different antenna feeds in accordance with the present invention. FIG. 38 is a diagram showing how an illustrative RF transceiver integrated circuit with five bands can be selectively connected to three different antenna feeds using two diplexers and a duplexer in accordance with the present invention. FIG. 39 is a diagram showing the return loss of an illustrative radiating element versus frequency as the switching circuitry of FIG. 3 8 selects between each of the three different antenna feeds in accordance with the present invention. FIG. 40 is a diagram of illustrative handheld electronic device circuitry including control circuitry that transmits and receives data, an RF module containing an RF transceiver integrated circuit and switching circuitry, and an antenna module having a multi-feed radiating element in accordance with the present invention. FIG. 41 is a diagram showing how an illustrative tester can be used to calibrate a circuit board containing a multi-feed antenna in accordance with the present invention. FIG. 42 is a cross-sectional side view of an illustrative RF switch connector for an RF module when the RF module is in normal operation in accordance with the present invention. FIG. 43 is a cross-sectional side view of an illustrative RF switch connector for an RF module when the RF module is being calibrated using a test probe in accordance with the present invention. FIG. 44 is a flow chart of illustrative steps involved in calibrating and using a handheld electronic device having a multi-feed antenna in accordance with the present invention. Detailed Description The present invention can relate to tunable antennas for portable electronic devices, such as handheld electronic devices. The invention can also relate to portable devices that contain tunable antennas and to methods for testing and using such devices and antennas. A tunable antenna in accordance with the invention can have a radiating element with multiple antenna feeds and a ground. The radiating element may be formed using any suitable antenna structure such as a patch antenna structure, a planar inverted-F antenna structure, a helical antenna structure, etc. The portable electronic devices may be small portable computers such as those sometimes referred to as ultraportables. With one particularly suitable arrangement, the portable electronic devices are handheld electronic devices. The use of handheld devices is generally described herein as an example. The handheld devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, and handheld gaming devices. The handheld devices of the invention may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid handheld devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes games and email functions, and a handheld device that receives email, supports mobile telephone calls, and supports web browsing. These are merely illustrative examples. Any suitable device may include a tunable multi-feed antenna, if desired. Illustrative antenna and control circuitry 10 that may be used in a handheld device in accordance with the invention is shown in FIG. 1. Circuitry 10 can include control circuitry 28. Control circuitry 28 may include one or more integrated circuits such as microprocessors, microcontrollers, digital signal processors, field programmable gate arrays, power amplifiers, and application-specific integrated circuits. Control circuitry 28 may also include passive RF components such as duplexers, diplexers, and filters. Control circuitry 28 may be mounted to one or more printed circuit boards 30 or other suitable mounting structures. Circuit board 30 may be, for example, a dual-sided circuit board containing patterned conductive traces. Control circuitry 28 can send and receive RF signals. The RF signals may be provided to an antenna module. The antenna module can contain a radiating element 12. Radiating element 12 may be formed from a highly-conductive material, such as copper, gold, alloys containing copper and other metals, high-conductivity non-metallic conductors (e.g., high-conductivity organic- based materials, high-conductivity superconductors, highly-conductive liquids), etc. in the example of FIG. 1, the radiating element 12 can have a thin planar profile, which facilitates placement of the radiating element 12 within a handheld device. The use of a radiating element with a planar structure is, however, merely illustrative. The radiating element 12 may be formed in any suitable shape. In the FIG. 1 example, slot 14 can be formed in radiating element 12, which increases the effective length of the radiating element 12, while maintaining a compact footprint. Radiating element 12 may be formed using any suitable manufacturing technique. With one suitable arrangement, the so-called foil stamping method can be used to form radiating element 12. with foil stamping techniques, a foil stamping machine is used to generate numerous radiating elements from a thin copper foil. Another suitable technique for forming radiating element can involve printing or etching the antenna pattern onto a fixed or flexible substrate. Flexible substrates that may be used during these patterning processes include so-called flex circuits (e.g., circuits formed from metals such as copper that are layered on top of flexible substrates such as polyimide). if desired, other techniques may be used to form radiating elements 12. The radiating element 12 can have a ground signal terminal and two or more corresponding positive signal terminals. The positive signal terminals can be called antenna feeds. In the example of FIG. l, radiating element 12 can have three elongated portions 16, 18, and 20. Elongated portion 16 may serve as ground. Elongated portion 18 may serve as a first feed. Elongated portion 20 may serve as a second feed. In general, there may be any suitable number of feeds in the antenna (e.g., two feeds, three feeds, four feeds, more than four feeds, etc.). Control circuitry 28 may include input-output terminals, such as ground input-output terminal 32 and positive input-output terminals 34 and 36. Conductive paths such as paths 22, 24, and 26 may be used to electrically connect the input-output terminals of control circuitry 28 to radiating element 12. Paths 22, 24, and 26 may be patterned conductive traces (e.g., metal traces) formed on printed circuit board 30. Paths 24 and 26 may be used to electrically connect positive input-output terminals 34 and 36 to elongated portions 18 and 20, respectively. A path such as path 2 2 may be used to connect the ground input-output terminal 32 to the ground portion 16 of radiating element 12. If desired, the upper and lower portions of printed circuit board 30 may also be connected to ground. The elongated portions 16, 18, and 20 may be soldered or otherwise electrically connected to paths 22, 24, and 26. In the example of FIG. l, the elongated portions 16, 18, and 20 are shown as being formed as an integral portion of radiating element 12 and paths 22, 24. and 26 are shown as being formed from circuit board traces. This is merely one suitable arrangement for connecting the ground and feeds of the radiating element 12 to the circuitry of the handheld device. Other suitable arrangement include contact arrangements based on external spring-loaded pins and spring connectors. Regardless of the particular type of arrangement that is used to convey signals into and out of the radiating element, the radiating element structure that is associated with ground is commonly referred to as the antenna's and radiating element's ground pin, ground terminal, or ground and the radiating element, structure that is associated with positive antenna signals is commonly referred to as the antenna's and radiating element's feed pin, feed terminal, or feed. The antenna formed from radiating element 14 has a resonant frequency f0 at which it can transmit and receive signals. The operating frequency range surrounding f0 is sometimes referred to as the fundamental band or fundamental operating frequency range of the antenna. If, as an example, fo is at 850 MHz, the antenna's fundamental frequency range can be used to cover a 850 MHz communications band. Antennas also generally resonate at higher frequencies that are harmonics of f0. With this type of arrangement, an antenna can cover two or more bands. For example, an antenna may be designed to cover both the 850 MHz band (using the antenna's fundamental frequency range centered on fo) and the 1800 MHz band (using a harmonic frequency range). The bandwidth associated with an antenna's operating frequency is influenced by the geometry of the radiating element 12. Antennas that are compact tend to have narrow bandwidths. Unless the bandwidth of the antenna is widened (e.g., by increasing its physical size), the antenna will not be able to cover nearby bands without tuning. As an example, consider the GSM cellular telephone standard, which uses bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. These bands may have bandwidths of about 70-80 MHz (for the 850 MHz and 900 MHz bands), 170 MHz (for the 1800 MHz band), and 140 MHz (for the 1900 MHz band). Each band may contain two associated subbands for transmitting and receiving data. For example, in the 850 MHz band, a subband that extends from 824 to 84 9 MHz may be used for transmitting data from a cellular telephone to a base station and a subband that extends from 869 to 894 MHz may be used for receiving data from a base station. The 850 MHz and 1900 MHz bands may be used in countries such as the United States. The 900 MHz and 1800 MHz may be used in countries such as the European countries. A compact antenna that is designed to cover the 850 MHz band may have a harmonic that allows it to simultaneously cover a higher band (e.g., 1900 MHz), but a compact antenna that has a narrow bandwidth will not be able to cover both the 850 MHz and 900 MHz bands unless it is tuned. In accordance with the present invention, control circuitry 28 may be used to select between different feeds to tune the antenna formed from radiating element 12. When, for example, signals are transmitted or received using ground terminal 32 and input-output terminal 34, the antenna covers one band. When signals are transmitted on received using ground terminal 32 and input-output terminal 36, the antenna covers a different band. Each feed (and its associated ground) may serve as an antenna port. An antenna such as an antenna formed from radiating element 12 of FIG. 1 therefore can have multiple ports and can be tuned by proper port selection. The control circuitry 28 can be used to determine which port is used. When access to a particular band is desired, the control circuitry 2 8 ensures that the proper port is active. By using multiple ports, a compact antenna with potentially narrow resonances can be tuned to cover all bands of interest. A graph containing an illustrative plot of return loss versus frequency for a tunable multi-port antenna in accordance with the present invention is shown in FIG. 2. Return loss is at a minimum at the antenna's fundamental operating frequency range. No harmonic frequency ranges are shown in FIG. 2. When signals are transmitted and received through a first antenna port (i.e., ground terminal 32, path 22, and radiating element extension 16 and positive input-output terminal 34, path 24, and radiating element extension 18), the antenna covers the frequency range centered at frequency fa, as shown by the solid line in FIG. 2 When signals are transmitted and received through a second antenna port (i.e., ground terminal 32, path 22, and radiating element extension 16 and positive input- output terminal 36, path 26, and radiating element extension 20), the antenna covers the frequency range centered at frequency fb, as shown by the dashed line in PIG. 2. This allows the control circuitry 28 to tune the antenna as needed, when it is desired to send or receive data in the fa range, the control circuitry 28 uses the first port. When the second port is used, the antenna's response is tuned to higher frequencies, so that the antenna covers a range of frequencies centered at fb. By using intelligent port selection, the coverage of an antenna can be extended to cover all frequency bands of interest. Because compact radiating elements tend to have small sizes, an antenna that is tuned by selecting a desired antenna port can be made more compact than would otherwise be possible, while still ensuring that all desired bands are covered. Moreover, tuning through the use of port selection can be more efficient than antenna tuning through adjustable capacitive loading schemes. Such capacitive loading schemes introduce reactive losses, which reduce antenna efficiency. An antenna with multiple feeds need not be tuned using variable capacitive loading because tuning can be performed through proper port selection. A schematic diagram of an illustrative handheld electronic device 38 containing a tunable multi-port antenna is shown in FIG. 3. Handheld device 38 may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a game player, a combination of such devices, or any other suitable portable electronic device. As shown in FIG. 3, handheld device 38 may include storage 40. Storage 40 may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., FLASH or electrically- programmable -read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. Processing circuitry 4 2 may be used to control the operation of device 38. Processing circuitry 42 may be based on a processor such as a microprocessor and other suitable integrated circuits. Input-output devices 44 may allow data to be supplied to device 38 and may allow data to be provided from device 38 to external devices. Input-output devices can include user input-output devices 4 6 such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device 38 by supplying commands through user input devices 46. Display and audio devices 48 may include liquid-crystal display (LCD) screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices 48 may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices 48 may contain audio-video interface equipment such as jacks for external headphones and monitors. Wireless communications devices 50 may include communications circuitry such as RF transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas such as the multiport antenna of FIG. 1, and other circuitry for generating RF wireless signals. wireless signals can also be sent using light (e.g., using infrared communications). The device 3 8 can communicate with external devices such as accessories 52 and computing equipment 54, as shown by paths 56. Paths 56 may include wired and wireless paths. Accessories 52 may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content). Computing equipment 54 may be a server from which songs, videos, or other media are downloaded over a cellular telephone link or other wireless link. Computing equipment 54 may also be a local host (e.g., a user's own personal computer), from which the user obtains a wireless download of music or other media files. As described in connection with FIG. 1, the multiport antenna used in the handheld device can be formed from any suitable radiating element 12. An example of a radiating element 12 that is formed from a rectangular patch antenna structure is shown in FIG. 4. The antenna structure of FIG. 4 and the other radiating element structures are preferably about one quarter of a wavelength in size (e.g., several centimeters for most cellular telephone wavelengths). The radiating element 12 of FIG. 4 may have a ground terminal 16, a first feed 18, a second feed 20, and potentially more feeds (shown by dotted feed structure 21). In general, any radiating element 12 may have more than two feeds, but only the radiating element 12 of FIG. 4 shows the additional feeds to avoid overcomplicating the drawings. Different fundamental resonant frequencies are associated with each of the different antenna ports and are influenced by the geometry of the radiating element 12. As shown in FIG. 4, when feed 18 is used, there is an inductive path in the antenna between feed 18 and ground 16. This path is shown schematically by dotted line 60. When feed 20 is used, there is a different inductive path in the antenna, shown by dotted line 58. Inductances L1 and L2 are associated with paths 60 and 58, respectively. The inductance L2 is generally larger than the inductance L1, so the port formed using feed 20 resonates at a higher frequency (e.g., frequency fb of PIG. 2) than the port formed using feed 18 (e.g., frequency fa of FIG. 2). An illustrative radiating element 12 that is formed from a rectangular patch antenna structure containing a slot 14 is shown in FIG. 5. Because of the presence of slot 14, the antenna of FIG. 5 will exhibit harmonics that are shifted with respect to the harmonics of the patch antenna structure of FIG. 4. This allows the antenna designer to place harmonics at desired communications bands. If desired, antenna ports may be formed on the shorter side of a rectangular patch. An illustrative structure of the type shown in FIG. 1 in which feeds have been placed on the shorter size of the rectangular patch is shown in FIG. 6. Another illustrative radiating element 12 is shown in FIG. 7. With the arrangement of FIG. 7, the rectangular patch structure has a cut-away portion 68. The cut-away portion 68 may be formed to accommodate a cellular telephone camera, a button, a microphone, speaker, or other component of the handheld device. Ports may be formed on the long side of the element 12 (e.g., using ground 16 and feeds 18 and 20) or on the short side of element 12 (e.g., using ground 16 and feeds 18a and 20a) . As shown in FIG. 8, the cut-away portion 68 need not be formed in the center of the radiating element 12. FIG. 9 shows how the sides of a radiating element may be bent downwards. Portions of the radiating element 12 such as portions 7 0 and 72 may be formed during a foil stamping process or by using a flex circuit. Portions 70 and 72 may serve as a fixed source of capacitive loading. Using bent-down portions in this type of arrangement tends to decrease the footprint of the radiating element for a given operating frequency. If desired, other forms of capacitive loading may be used with radiating element. Capacitive loading can be used with the patch antenna structure of PIG. 7 (as shown in the example of FIG. 9) or with any other suitable radiating element structure. If desired, a radiating element 12 may be formed from a flex circuit or other flexible substrate. In the example of FIG. 10, radiating element 12 is formed from a conductive element 62 that is formed in a serpentine pattern on flex circuit substrate 64. After the serpentine pattern is formed on substrate 64, the substrate 64 is curled to form the cylindrical shape of FIG. 10. The cylindrical antenna of FIG. 10 has a ground 16 and two feeds 18 and 20. In the illustrative arrangement of FIG. 11, radiating element 12 is formed from a patch antenna having a serpentine slot 14. in general, one or more slots of any suitable shape may be formed in the radiating element 12. FIG. 12 shows an illustrative arrangement for a radiating element 12 that is based on an L-shaped planar antenna arrangement. The radiating element 12 of FIG. 12 has a ground 16 and feeds 18 and 20. In FIG. 13, the ground terminal 16 is formed using a separate conductor from the conductive element that contains feeds 18 and 20. FIG. 14 shows an illustrative radiating element 12 that is formed from a separate ground element 16 and serpentine element 66. Feeds 18 and 20 are formed at different locations in the serpentine element 66. The radiating element structures show in FIGS. 1 and 4-14 are merely illustrative. In general, any suitable radiating element structures with multiple feeds may be used. As shown in FIG. 15, a printed circuit board such as printed circuit board 30 of FIG. 1 may have an upper surface of conductive material 74 and a lower surface of conductive material 76 separated by an insulating printed circuit board layer 78. The upper and lower conductive surfaces may contain a patterned metal such as copper. The lower surface may be relatively unpatterned and may be used to form a ground plane. Ground wires on the upper surface may be connected to the lower surface ground plane using conductive vias 80. When mounting the radiating element 12 to the printed circuit board 30, the patterned conductors on the upper surface of printed circuit board 30 may be used to form electrical contact with the radiating element. Electrical contact may be made using any suitable electrical connecting structures. In the example of FIG. 16, an elongated portion of radiating element 12 (e.g., a ground or feed element of the type shown in FIG. 1) is shown as forming a spring 82. When the antenna is mounted in proximity to the circuit board, the spring portion B2 presses against a conductive trace 84 on the upper surface 74 of circuit board 30. This forms an electrical contact between trace 84 (which is connected to control circuitry 28 of FIG. 1) and the radiating element 12. If desired, spring-loaded pins may be used to make electrical contact between a radiating element 12 and circuit board 30. One commonly-available spring- loaded pin is the so-called pogo pin. A cross-sectional side view of a spring-loaded pin 86 is shown in FIG. 17. Pin 86 has a reciprocating member 88 with a head portion 90 that reciprocates within a hollow cylindrical pin housing 98. A spring 92 bears against the inner surface 94 of pin housing 98 and the upper surface 96 of head 90. When member 88 is withdrawn within housing 98, spring 92 is compressed and biases reciprocating member 88 in direction 100. This drives the tip 102 of member 88 against a conductive element such as a portion of a circuit board or a radiating element. FIG. 18 shows an arrangement in which a spring- loaded pin 86 has been soldered to a radiating element 12 with solder 104. The tip 102 of the pin presses against a conductor on the surface of circuit board 30. In the arrangement of FIG. 19, the spring- loaded pin 86 has been soldered to a circuit board 3 0 and is pressing upward against the radiating element 12, so that the tip 102 of reciprocating member 88-makes electrical contact with the radiating element. FIG. 20 shows an arrangement in which a spring 108 has been soldered to a circuit board 30 with solder 106. A portion 112 of radiating element 12 has been bent downward. The portion 112 of radiating element 12 may be formed during a metal foil stamping process (as an example). As shown in FIG. 20, spring 108 is compressed and bears against the portion 112, thereby forming electrical contact between radiating element 12 and circuit board 30. The arrangement of FIG. 21 is similar to the arrangement of FIG. 20, but involves forming an electrical connection to a radiating element 12 that is fabricated from a flex circuit. The radiating element 12 has a post 110. As shown in FIG. 21, a spring 108 that has been soldered to circuit board 30 with solder 106 bears against post 110 to form electrical contact. The pins and springs of FIGS. 18, 19, 20, and 21 need not be soldered to the circuit board or radiating element 12. Arrangements in which the connecting electrical structure is not soldered are said to be floating. FIGS. 22 and 23 show floating pin arrangements in which pin 86 forms an electrical connection between radiating element 12 and circuit board 30. In the arrangement of FIG. 22, the tip 102 of pin 86 presses against the radiating element 12. In the arrangement of FIG. 23, the tip 102 of pin 86 presses downward against a conductor on circuit board 30. Any suitable circuit architecture may be used to interconnect the control circuitry 28 with the feeds of the antenna and radiating element 12. Consider, as an example, the arrangement of FIG. 24. As shown in FIG. 24, an RF transceiver integrated circuit 114 is connected to ground 16. RF transceiver integrated circuit 114 is also connected to two antenna feeds 18 and 20 using input-output data paths 115 and switching circuitry formed from switches 116. Switches 116 may be formed from PIN diodes, high-speed field-effect transistors (FETs), or any other suitable switch components. The switches for each feed are complementary and work in tandem. The state of each switch is the inverse of the other. When switch SW1 is on, switch SW2 is off and a first antenna port is active while a second antenna port is inactive. when switch SW1 is off, switch SW2 is on and the first antenna port is inactive while the second antenna port is active. Using this type of arrangement ensures that only one feed is active at a time. feed1 is active and feed2 is inactive when switch SW1 is on and switch SW2 is off. Feed2 is active and feed1 is inactive when switch SW2 is on and switch SW1 is off. The graph of FIG. 25 shows the frequency response of the radiating element 12 in two conditions. The solid line shows the return loss of the radiating element at its fundamental operating frequency range when the first port is active. In this configuration, the antenna is tuned so that it operates at the frequency fa. The dashed line in FIG. 25 shows the return loss of the radiating element when the second port is active, in this configuration, the antenna is tuned so that it operates at frequency fb. In the arrangement of FIG. 26, switch SW1 may handle two different bands (fa and fb), whereas switch SW2 may handle frequency band fc. Switch SW1 has three states, in its first state, input-output signal path 118 is connected to feed1 and the antenna operates at frequency fa. as shown in FIG. 27. In its second state, input-output signal path 12 0 is connected to feed1 and the antenna operates in band fb. As described in connection with FIG. 24, switch SW2 is off whenever switch SW1 is on. When it is desired to tune the antenna, the control circuitry 2 8 places switch SW1 in a third state in which lines 118 and 12 0 are disconnected from feed1 (i.e.-, switch SW1 is off). When switch SW1 is turned off, switch SW2 is turned on, so the antenna operates at shifted fundamental frequency fc (FIG. 27). As shown in FIGS. 28 and 29, passive RF components such as duplexers and diplexers may be used to couple RF transceiver 114 to the antenna feeds. A duplexer can be used to combine or separate RF signals that are in adjacent bands (e.g., 850 MHz and 900 MHz). A diplexer can be used to combine or separate RF signals that are in distant bands (e.g., 850 MHz and 1800 MHz). As shown in FIG. 28, duplexer 122 may be coupled between data paths 118 and 12 0 and switch SW1. Switch SW2 is coupled between data path 126 and feed2. When it is desired to use feed1, switch SW1 is turned on and switch SW2 is turned off. This tunes the antenna so that it operates according to the solid line of FIG. 29. In this state, RF transceiver 114 can use paths 118 and 120 to transmit and receive in either frequency band fa or frequency band fb, because the radiating element 12 of the antenna is designed to have a sufficiently large bandwidth in its fundamental operating frequency range to handle the adjacent bands fa and fb. When it is desired to tune the antenna by using feed2, switch SW1 is turned off and switch SW2 is turned on. In this state, path 126 is connected to feed2 and transceiver 114 can transmit and receive signals using band fc, as shown by the dotted line in FIG. 29. In the arrangement of FIG. 30, a diplexer 124 is used in place of a duplexer. The radiating element 12 in this scenario is designed to have a harmonic at fb- Because a diplexer 124 is being used, the signals associated with paths 118 and 120 must be more widely separated than in the duplexer arrangement of FIG. 28. As shown by the solid line in FIG. 31, when feed1 is switched into use by turning on SW1 and turning off SW2, transceiver 114 can use paths 118 and 120 to transmit and receive in either fundamental frequency band fa or harmonic frequency band fb. When it is desired to tune the antenna by using feed2, switch SW1 is turned off and switch SW2 is turned on. In this state, path 126 is connected to feed2 and transceiver 114 can transmit and receive signals using band fc, as shown by the dotted line in FIG. 31. The bands used in GSM communications each have two subbands, one of which contains channels for transmitting data and the other of which contains channels for receiving data. As shown in FIG. 32, a switch 116 can be used to connect an appropriate transmit or receive data path to its associated feed 128. Paths 118a and 118b are connected to the RF transceiver. In GSM communications, signals are either transmitted or are received. Simultaneous transmission and reception is not permitted. When the RF transceiver has data to transmit, switch 116 connects the transmit line 118a to feed 128. In receive mode, the switch 116 is directed to connect feed 128 to path 118b. When it is desired to inactivate the feed 128, switch 116 may be turned off. In the example of FIG. 32, paths 118a and 118b are labeled 850T (850 MHz transmit) and 8S0R (850 MHz receive). The same principal applies to all GSM bands. The input-output data paths connected to the RF transmitter 114 in FIGS. 24, 26, 28, and 30 are shown as single bidirectional paths rather than as separate transmit and receive paths to avoid over-complicating the drawings. An arrangement in which a duplexer 122 may be used to couple an RF transceiver to a feed 128 is shown in FIG. 33. When incoming data is received on feed 128 or when outgoing data is being transmitted, switch 116 is on. Switch 116 is off when it is desired to tune the antenna by using a different feed. Duplexer 12 2 is frequency sensitive. Incoming data (e.g., on the 850R subband) is routed to line 118b by the passive RF components in duplexer 122. When outgoing data is transmitted on line 118a, duplexer 12 2 routes those signals to line 128 via switch 116. When architectures of the type shown in FIGS. 24, 26, 28, and 30 are used for GSM-type communications, an active subband switching arrangement of the type shown in FIG. 32 or a passive subband routing arrangement of the type shown in FIG. 33 may be used. In either case, switching circuitry 116 is used to ensure that the appropriate antenna feed is active. In some communications protocols such as those based on code division multiple access (CDMA) technology, signals can be transmitted and received simultaneously. There is therefore no need for a switch to actively switch between transmit and receive bands. Examples of communications schemes that use CDMA technology include CDMA cellular telephone communications and 3G data communications over the 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System). With CDMA-based arrangements, a duplexer arrangement of the type shown in FIG. 33 may be used to separate transmitting and receiving frequencies from each other. Some handheld devices need to cover many bands. An example of an arrangement that may be used to cover five bands (e.g., the four GSM bands plus the UMTS band) using a two port antenna is shown in FIG. 34. A graph showing the placement of each of the bands is shown in FIG. 35. The antenna is designed to have a fundamental operating frequency range 128 at about 850-900 MHz and a harmonic operating frequency range 13 0 at about 1800- 1900. When switch SW1 is on and switch SW2 is off, feed1 is active and the antenna's response is as shown by the solid line in FIG. 35. The antenna is designed to have a relatively broad bandwidth at its fundamental and harmonic operating frequencies. As a result, the antenna covers both the 850 MHz and 900 MHz GSM bands in the fundamental operating frequency range 128 and covers both the 1800 MHz and 1900 MHz GSM bands using the harmonic operating frequency range 130. When switch SW2 is on and switch SWl is off, feed 2 is active and the antenna is tuned. This shifts the harmonic operating frequency range 13 0 to a higher frequency, so that it covers the UMTS band at 2170 MHz. An example of an arrangement that may be used to cover four bands (e.g., the four GSM bands) using a two port antenna is shown in FIG. 36. Diplexers 124 are used to couple RF transceiver 114 to switching circuitry 116. One diplexer 124 handles the 850 MHz and 1800 MHz bands while the other diplexer 124 handles the 900 MHz and 1900 MHz bands. A graph showing the placement of each of the bands is shown in FIG. 37. The antenna is designed to have a fundamental operating frequency range 128 at about 850 MHz and a harmonic operating frequency range 130 at about 1800. When switch SW1 is on and switch SW2 is off, feed1 is active and the antenna's response is as shown by the solid line in FIG. 37. The antenna has a narrow bandwidth that covers a single band at each resonant frequency. As shown by the solid line in FIG. 37, when feed1 is used, the antenna can cover both the 850 MHz and 1800 MHz bands. When it is desired to tune the antenna, switches 116 are adjusted so that feed2 is used. This shifts both the fundamental operating range 128 and the harmonic operating frequency range 13 0 to higher frequencies, so as to cover the 900 MHz and 190 0 MHz bands, respectively, as shown by the dashed line in FIG. 37. An example of an arrangement that may be used to cover five bands (e.g., the four GSM bands and the UMTS band) using a three port antenna is shown in FIG. 38. Diplexers 124 are used to couple RF transceiver 114 to switching circuitry 116. One diplexer 124 handles the 850 MHz and 1800 MHz bands while the other diplexer 124 handles the 900 MHz and 1900 MHz bands. The placement of each of the bands is shown in the graph of FIG. 39. When feed1 is used, the antenna is has a fundamental operating frequency range 128 at about 850 MHz and a harmonic operating frequency range 130 at about 1800 MHz. when switch SW1 is on and switches SW2 and SW3 are off, feed1 is active and the antenna's response is as shown by the solid line in FIG. 39. As shown by the solid line in FIG. 39, when feed1 is used, the antenna covers both the 8 50 MHz and 1800 MHz bands. Due to the relatively narrow bandwidth of the antenna, adjacent bands are not covered without tuning. When it is desired to tune the antenna to cover the 900 MHz and 1900 MHz bands, switches 116 are adjusted so that feed2 is used. This shifts both the fundamental operating range 128 and the harmonic operating frequency range 130 to higher frequencies, so as to cover the 900 MHz and 1900 MHz bands, respectively, as shown by the dashed line in FIG. 39. When it is desired to tune the antenna to cover the 2170 MHz band, switches 116 are adjusted so that feed3 is switched into use. As a result, the fundamental operating range 128 and the harmonic operating frequency range 130 are shifted to higher frequencies. With this antenna tuning configuration, the harmonic operating frequency range 130 covers the 2170 MHz band, as shown by the dot-and-dashed line in FIG. 39. FIG. 40 shows details of an arrangement of the type described in FIGS. 34 in which five bands are covered (e.g., the four GSM bands and the UMTS band) using two antenna ports. Processing circuitry 42 can generate data to be transmitted and can provide this data to RF module 132 in wireless communications circuitry 50 using a path such as path 140. Data that is received by the handheld device may be routed from RF module 132 to processing circuitry 42 via path 142. Transceiver 114 can be coupled to radiating element 12 in antenna module 134 via feed1, feed2, and ground. Switching circuitry 116 can be used to regulate which antenna port is active. Switch sw1 can be used to select a desired GSM signal path to connect to feed1 when feed1 is active and is used to disconnect feed1 from the RF transmitter when feed1 is inactive. Switch SW2. which is on when switch SWl is inactive, can used to seletively activate feed2. Switch SW2 can receive transmitted signals from RF transceiver 114 and can deliver received signals to RF transceiver 114 through duplexer 122, which can handle the transmit and receive subbands for a 2170 MHz UMTS band. A power amplifier integrated circuit 136 may be used to boost outgoing signal levels. Power amplifier integrated circut 136 contains power amplifiers 138. The power amplifiers may be provided as separate integrated circuits if desired. A testing arrangement that may be used to calibrate an RF module 132 during the process of manufacturing a handheld device 38 is shown in FIG. 41. During testing, tester 144 can apply power and control signals to processing circuitry 42 using a path such as path 14 7. The control signals may direct the processing circuitry 42 to transmit signals to antenna module 134. Each feed can be calibrated in turn. Tester 144 has a cable and test probe that can be connected to either RF switch connector 152 (when the cable and probe are in the position indicated by line 148) or RF switch connector 156 (when the cable and probe are in the position indicated by line 150). During testing, the probe taps into the signals that would otherwise be transmitted over antenna module 134. RF switch connectors 152 and 156 have two operating conditions. A cross-section of an illustrative RF switch connector 166 is shown in FIGS. 42 and 43. When no test probe is inserted, as shown in FIG. 42, input 160 is connected to output 162 via conductor 164. When the tip of a test probe 168 is inserted into switch connector 166, conductor 164 is pressed downwards, which opens the circuit between conductor 164 and output 162 and electrically connects input 160 to the test probe 168. RF switch connector 152 may be used to tap into signals that would normally pass from data path 154 to feed1, whereas RF switch connector 156 may be used to tap into signals that would normally pass from data path 158 to feed2. During calibration, tester 144 measures the signal strenth received on each feed for a variety of output power settings. Using curve fitting techniques, tester 144 determines which calibration settings should be stored in the circuitry 10. The calibration settings are loaded into non-volatile memory 40 such as flash memory over a path such as path 146. Later, during normal operation, processing circuitry 42 uses the stored calibration settings to make calibrating adjustments to the output signal levels of the RF module 132. Illustrative steps involved in testing and fabricating handheld devices with tunable multi-port antennas are shown in FIG. 44. At step 170, a circuit board assembly containing the RF moudule 132 and antenna module 134 can be fabricated. At step 172, tester 144 of FIG. 41 may send control signals to processing circuitry 42 via path 147. The control signals direct the processing circuitry 42 to use transceiver 114 and switching circuitry 116 to transmit suitable test signals to the antenna on feeds IB and 20. Each feed is excercised separately. To ensure accurate measurements, test signals may be transmitted using several different power settings while tester 144 gathers associated test measurements. At step 174, the tester 144 can process the test measurements (e.g., using curve-fitting routines) and generates corresponding calibration settings. The calibration settings indicate what adjustments need to be made by RF module 132 during normal operation to ensure that the transmitted RF power levels are accurate. The tester 144 can store the calibration information in memory 40 at step 176. With one suitable arrangement, the calibration information is stored in a non-volatile memory such as a flash memory to ensure that the calibration information will be retained in the event of a loss of power by the handheld electronic device 38. During steps 178 and 180, the handheld electronic device 38 may be used by a user to place cellular telephone calls, to upload or download data over a 36 link, or to otherwise wirelessly transmit and receive data. During step 178, the processing circuitry 42 (FIG. 41) retrieves the calibration settings data from memory 40 and uses the retrieved calibration settings to adjust the power output of the handheld device so that the output power is calibrated. The processing circuitry 42 calibrates each port separately, so the output power is accurate regardless of which antenna port is being used. During step 180, the user can transmit and receive data using the antenna. The processing circuitry 42 tunes the antenna as needed by selecting an appropriate antenna feed using switching circuitry 116. The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. What is Claimed is: 1. A tunable multiport handheld electronic device antenna, comprising: a radiating element; a ground terminal that is electrically connected to the radiating element; and at least first and second antenna feeds, wherein the first antenna feed is electrically connected to the radiating element at a first location, wherein the second antenna feed is electrically connected to the radiating element at a second location that is different from the first location, wherein the first antenna feed and the ground form a first antenna port, and wherein the second antenna feed and the ground form a second antenna port. 2. The tunable multiport handheld electronic device antenna defined in claim l wherein the radiating element comprises a patch antenna structure. 3. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises a metal antenna structure without adjustable capacitive loading. 4. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises first, second, and third integral elongated portions, wherein the first elongated portion forms the ground, wherein the second elongated portion forms the first feed, and wherein the third elongated portion forms the second feed. 5. The tunable multiport handheld electronic device antenna defined in claim 1 wherein the radiating element comprises metal and is configured to operate at a frequency range associated with a first cellular telephone band when the first port is used and is configured to operate at a frequency range associated with a second cellular telephone band that is different from the first cellular telephone band when the second port is used. 6. A handheld electronic device comprising: storage that stores data; processing circuitry coupled to the storage that generates data for wireless transmission and that processes wirelessly-received data; and wireless communications circuitry that communicates with the processing circuitry, wherein the wireless communications circuitry contains a tunable multiport antenna containing a ground, a first antenna feed, and a second antenna feed, wherein the processing circuitry tunes the antenna by selecting whether to use the first antenna feed or the second antenna feed in wirelessly transmitting and receiving data. 7. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises: a radio - frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a separate communications band; and switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path. 8. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises: a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna's fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna's harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna's harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands. 9. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises: a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna's fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna's harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna's harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands, wherein the second band has a higher frequency than the first band, wherein the third band has a higher frequency than the second band, wherein the fourth band has a higher frequency than the third band, wherein the fifth band has a higher frequency than the fourth band, wherein the first, second, third, and fourth communications bands are cellular telephone bands and wherein the fifth band is a data band. 10. The handheld electronic device defined in claim 6 wherein the wireless communications circuitry comprises: a radio-frequency transceiver having a plurality of associated paths, each path being configured to carry signals associated with a respective one of a set of at least five different communications bands; and switching circuitry that selectively connects the first feed or the second feed to an active one of the plurality of associated paths to tune the antenna so that the antenna operates at the communications band associated with the active path, wherein the antenna transmits and receives signals in a fundamental frequency range and a harmonic frequency range, wherein when the first feed is connected, the antenna's fundamental frequency range is used to transmit and receive signals associated with a first one of the five bands and a second one of the five bands and the antenna's harmonic frequency range is used to transmit and receive signals associated with a third one of the five bands and a fourth one of the five bands, and wherein when the second feed is connected, the antenna's harmonic frequency range is used to transmit and receive signals associated with a fifth one of the five bands, wherein the first band is centered at about 850 MHz, wherein the second band is centered at about 900 MHz, wherein the third band is centered at about 1800 MHz, wherein the fourth band is centered at about 1900 MHz, and wherein the fifth band is centered at about 2170 MHz. 11. Tunable multiport antenna circuitry comprising: a radiating element; a circuit board having a ground conductive path and first and second antenna feed conductive paths; a ground electrical connecting structure that connects the ground conductive path to the radiating element and serves as a ground terminal for the radiating element; a first feed electrical connecting structure that electrically connects the first feed conductive path on the circuit board to the radiating element at a first location and serves as a first feed terminal for the radiating element; and a second feed electrical connecting structure that electrically connects the second feed conductive path on the circuit board to the radiating element at a second location distinct from the first location and serves as a second feed terminal for the radiating element. 12. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a spring-loaded pin. 13. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a piece of bent conductor that serves as a spring. 14. The tunable multiport circuitry defined in claim 11 wherein at least one of the ground electrical connecting structure, the first feed electrical connecting structure, and the second feed electrical connecting structure comprises a piece of bent conductor formed as an integral part of the radiating element that serves as a spring and that is soldered to one of the conductive paths on the circuit board. 15. The tunable multiport circuitry defined in claim n wherein the circuit board has a third feed conductive path, the circuitry further comprising: a third feed electrical connecting structure that electrically connects the third feed conductive path on the circuit board to the radiating element at a third location distinct from the first and second locations and that serves as a third feed terminal for the radiating element. 16. A method for calibrating and using a tunable multiport antenna in a handheld electronic device, comprising: fabricating a circuit board assembly that contains a radio-frequency module, a radiating antenna element that is connected to the radio-frequency module with a ground and at least first and second antenna feeds, processing circuitry, and non-volatile memory, wherein the radio-frequency module contains at least a first radio-frequency switch connector for tapping into the first feed with a test probe and a second radio- frequency switch connector for tapping into the second feed with the test probe; and sending control signals to the processing circuitry from a tester while measuring output signal powers for the first and second antenna feeds using the first and second radio-frequency switch connectors, wherein only a single one of the first and second antenna feeds is active at a given time. 17. The method defined in claim 16 further comprising: determining calibration settings based on the measured output signal powers; and storing the calibration settings in the non-volatile memory. 18. The method defined in claim 16 further comprising: determining calibration settings based on the measured output signal powers; storing the calibration settings in the non-volatile memory; and transmitting and receiving data through the antenna radiating element using the calibration settings. 19. A method for using a tunable multiport antenna in a handheld electronic device, wherein the tunable multiport antenna has a first antenna port formed from a ground and a first antenna feed and has a second antenna port formed from a ground" and a second antenna feed, wherein the handheld electronic device comprises a radio-frequency transceiver having associated data paths each of which carries signals for a different communications band, and wherein the handheld electronic device comprises switching circuitry that is coupled between the radio-frequency transceiver and the first and second antenna feeds, the method comprising: adjusting the switching circuitry to activate a single selected one of the first and second antenna ports while deactivating the other of the first and second antenna ports; and conveying signals between the transceiver and the single selected antenna port using one of the data paths and the antenna feed and ground of the single selected antenna port. 20. The method defined in claim 19 wherein the handheld electronic device comprises non-volatile memory in which calibration settings for the first and second antenna ports have been stored and wherein conveying the signals comprises: transmitting signals from the transceiver using the calibration settings, wherein when the first antenna port is activated by the switching circuitry, the tunable multiport antenna transmits and receives signals in a fundamental frequency range containing at least a first communications band and transmits and receives signals over a harmonic frequency range containing at least a second communications band, wherein when the second antenna port is activated by the switching circuitry, the tunable multiport antenna transmits and receives signals in the harmonic frequency range containing at least a third communications band, and wherein the second and third communications bands are different. 21. Wireless communications circuitry comprising: a tunable multiport radiating element having a ground terminal and at least first and second feed terminals, wherein the first feed terminal and the ground terminal form a first antenna port, wherein the second feed terminal and the ground terminal form a second antenna port; a transceiver having a number of associated signal input-output paths that convey signals to and from the antenna; and switching circuitry that tunes the tunable multiport radiating element by selectively activating the first port and the second port, wherein the switching circuitry activates the first port by connecting a first one of the input-output paths to the first feed while disconnecting the second feed from the input-output paths and wherein the switching circuitry activates the second port by connecting a second one of the input-output paths to the second feed while disconnecting the first feed from the input-output paths. 22. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range and wherein the signal input- output paths comprise: a first input-output path that is configured to transmit and receive signals for a first communications band; a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; and a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein when the first port is active, the first communications band lies within the fundamental frequency range and the second communications band lies within the harmonic frequency range and wherein when the second port is active, the third communications band lies within the harmonic frequency range. 23. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise: a first input-output path that is configured to transmit and receive signals for a first communications band; a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; and a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein when the first port is active, the first communications band lies within the fundamental frequency range and the second communications band lies within the harmonic frequency range, wherein when the second port is active, the third communications band lies within the harmonic frequency range, and wherein the duplexer is coupled within the third input- output path between the transceiver and the switching circuitry. 24. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise: a first input-output path that is configured to transmit and receive signals for a first communications band; a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein the duplexer is coupled within the third input-output path between the transceiver and the switching circuitry; a fourth input-output path that is configured to transmit and receive signals for a fourth communications band that is different than the first, second, and third communications bands; and a fifth input-output path that is configured to transmit and receive signals for a fifth communications band that is different than the first, second, third, and fourth communications bands, wherein when the first port is active, the first and fourth communications bands lie within the fundamental frequency range and the second and fifth communications bands lie within the harmonic frequency range and wherein when the second port is active, the third communications band lies within the harmonic frequency range. 25. The wireless communications circuitry defined in claim 21 wherein the radiating element is configured to operate over a fundamental frequency range and a harmonic frequency range that is higher than the fundamental frequency range, the wireless communications circuitry further comprising power amplifiers that amplify at least some of the signals on the input-output paths and at least one radio-frequency duplexer, wherein the signal input-output paths comprise: a first input-output path that is configured to transmit and receive signals for a first communications band; a second input-output path that is configured to transmit and receive signals for a second communications band that is different than the first communications band; a third input-output path that is configured to transmit and receive signals for a third communications band that is different than the first and second communications bands, wherein the duplexer is coupled within the third input-output path between the transceiver and the switching circuitry; a fourth input-output path that is configured to transmit and receive signals for a fourth communications band that is different than the first, second, and third communications bands; and a fifth input-output path that is configured to transmit and receive signals for a fifth communications band that is different than the first, second, third, and fourth communications bands and that is associated with a data service, wherein when the first port is active, the first and fourth communications bands lie within the fundamental frequency range and the second and fifth communications bands lie within the harmonic frequency range, wherein when the second port is active, the third communications band lies within the harmonic frequency range, and wherein the first, second, third, and fourth communications bands each include non- overlapping transmit and receive subbands. A compact tunable antenna for a handheld electronic device and methods for calibrating and using compact tunable antennas are provided. The antenna can have multiple ports. Each port can have an associated feed and ground. The antenna design can be implemented with a small footprint while covering a large bandwidth. The antenna can have a radiating element formed from a conductive structure such as a patch or helix. The antenna can be shaped to accommodate buttons and other components in the handheld device. The antenna may be connected to a printed circuit board in the handheld device using springs, pogo pins, and other suitable connecting structures. Radio- frequency switches and passive components such as duplexers and diplexers may be used to couple radio- frequency transceiver circuitry to the different feeds of the antenna. Antenna efficiency can be enhanced by avoiding the use of capacitive loading for antenna tuning.

Full Text

TUNABLE ANTENNAS FOR HANDHELD DEVICES
This application claims priority to United
States patent application No. 11/516,433, filed september
5, 2006.
Background
This invention can relate to antennas, and more
particularly, to compact tunable antennas used in
wireless handheld electronic devices.
Wireless handheld devices, such as cellular
telephones, contain antennas. As integrated circuit
technology advances, handheld devices are shrinking in
size. Small antennas are therefore needed.
A typical antenna for a handheld device is
formed from a metal radiating element. The radiating
element may be fabricated by patterning a metal layer on
a circuit board substrate or may be formed from a sheet
of thin metal using a foil stamping process. These
techniques can be used to produce antennas that fit
within the tight confines of a compact handheld device.
Modern handheld electronic devices often need
to function over a number of different communications
bands. For example, quad-band cellular telephones that
use the popular global system for mobile (GSM)

communications standard need to operate at four different
frequencies (850 MHz, 900 MHz, 1800 MHz, and 1900 MHz).
Although multi-band operation is desirable, it
is difficult to design a compact antenna that functions
satisfactorily over a wide frequency range. This is
because small antennas tend to operate over narrow
frequency ranges due to the small dimensions of their
radiating elements.
Antennas with tunable capacitive loading have
been developed in an attempt to address the need for
compact multi-band antennas. By varying the amount of
capacitive loading that is applied to the radiating
element, the resonant frequency of the antenna can be
adjusted. This allows an antenna with a relatively
narrow frequency range to be tuned sufficiently to cover
more than one band.
The adjustable capacitive loading that is
placed on this type of antenna leads to unwanted power
loss. As a result, capacitively-tuned antennas tend to
exhibit less-than-optimal efficiencies.
It would be desirable to be able to provide
ways in which to improve the performance of tunable
antennas for handheld electronic devices.
Summary
In accordance with the present invention,
tunable multiport antennas are provided. Handheld
devices that use the tunable multiport antennas and
methods for calibrating and using the tunable multiport
antennas are also provided.
A tunable multiport antenna can have a ground
terminal and multiple feed terminals. Each feed terminal

can be used with the ground terminal to form a separate
antenna port. By selecting which antenna port is active
at a given time, the antenna's operating frequencies can
be tuned.
Tunable multiport antennas contain radiating
elements. The radiating elements may be formed, for
example, by a foil stamping process or by patterning a
conductive layer on a substrate such as a printed circuit
board or flex circuit. Each radiating element can
resonate at a fundamental frequency range. The
dimensions of the radiating element may be chosen to
align the antenna*s fundamental operating frequency range
with at least one communications band. If desired, the
radiating element may also be used at one or more
harmonic frequency ranges.
The radiating element can be coupled to a
printed circuit board on which electronic components for
a handheld electronic device are mounted. The printed
circuit board can contain conductive traces that connect
the components to the ground and feed terminals of the
antenna. Electrical connecting structures, such as
springs and spring-loaded pins, can be used to
electrically connect the conductive traces on the printed
circuit board to the ground and feeds of the radiating
element.
Handheld electronic devices can contain radio-
frequency transceivers and switching circuitry. The
radio-frequency transceivers can have input-output paths
that are used to transmit and receive signals associated
with different communications bands. The switching
circuitry can selectively connects the input-output paths
to the ports of the antenna. During operation of a

handheld electronic device, control circuitry on the
device can direct the switching circuitry to activate a
desired one of the antenna ports. By selecting which
antenna port is active, the control circuitry can tune
the antenna so that one or more of the antenna's
operating frequency ranges aligns with one or more
desired communications bands.
Because the antenna can be tuned, it is not
necessary to enlarge the dimensions of the radiating
element to broaden the bandwidth of the radiating
element's resonant frequencies. This allows the antenna
to be implemented with a small footprint. The use of
multiple feeds in the radiating element permits tuning
without the use of adjustable capacitive loading, which
reduces reactive antenna losses and enhances antenna
efficiency.
Further features of the invention, its nature
and various advantages will be more apparent from the
accompanying drawings and the following detailed
description of the preferred embodiments.
Brief Description of the Drawings
FIG. 1 is a perspective view of an illustrative
circuit board to which a multi-port antenna is mounted in
accordance with the present invention.
FIG. 2 is a graph in which the return loss of
the antenna of FIG. 1 has been plotted as a function of
frequency in accordance with the present invention.
FIG. 3 is a schematic diagram of an
illustrative handheld device containing a tunable antenna
in accordance with the present invention.
FIGS. 4-14 are diagrams of illustrative antenna

radiating elements having multiple feeds that can be
selected for timing in accordance with the present
invention.
FIG. 15 is a side view of an illustrative
printed circuit board showing how vias can be used to
connect the upper and lower surfaces of the printed
circuit board to form a ground plane for an antenna of
the type show in FIG. 1 in accordance with the present
invention.
FIG. 16 is a perspective view of an
illustrative portion of a circuit board assembly showing
how a radiating element with an integral spring may be
used to make contact between to a pad on a printed
circuit board of the type shown in FIG. 15 in accordance
with the present invention.
FIG. 17 is a cross-sectional side view of an
illustrative spring-loaded pin that may be used to
connect an antenna's radiating element to a circuit board
in accordance with the present invention.
FIG. 18 is a cross-sectional side view showing
use of an illustrative spring-loaded pin that is soldered
to a radiating element to make contact with a printed
circuit board in accordance with the present invention.
FIG. 19 is a cross-sectional side view showing
use of an illustrative spring-loaded pin that is soldered
to a printed circuit board to make contact with an
antenna's radiating element in accordance with the
present invention.
FIG. 20 is a cross-sectional side view showing
use of an illustrative spring to make contact between a
radiating element and a printed circuit board in
accordance with the present invention.

FIG. 21 is a cross-sectional side view showing
use of an illustrative spring that is attached to a
printed circuit board to make contact with a post of a
radiating element formed from flexible circuit board
material in accordance with the present invention.
FIGS. 22 and 23 are cross-sectional side views
showing use of an illustrative floating spring-loaded pin
to make contact between a radiating element and a printed
circuit board in accordance with the present invention.
FIG. 24 is a circuit diagram showing how
illustrative switches may be used to selectively connect
a radio-frequency (RF) transceiver integrated circuit
operating in two frequency bands to two different antenna
feeds in accordance with the present invention.
FIG. 25 is a graph showing the return loss of
an illustrative radiating element versus frequency as the
circuitry of FIG. 24 selects between each of two
different antenna feeds on the radiating element in
accordance with the present invention.
FIG. 26 is a circuit diagram showing how
illustrative switches may be used to selectively connect
a radio-frequency (RF) transceiver integrated circuit
operating in three frequency bands to two different
antenna feeds in accordance with the present invention.
FIG. 27 is a graph showing the return loss of
an illustrative radiating element versus frequency as the
circuitry of FIG. 26 selects between each of two
different antenna feeds on the radiating element in
accordance with the present invention.
FIG. 28 is a circuit diagram showing how
illustrative switches and a passive antenna duplexer may
be used to selectively connect a radio-frequency (RF)

transceiver integrated circuit operating in three
frequency bands to two different antenna feeds in
accordance with the present invention.
FIG. 29 is a graph showing the return loss of
an illustrative radiating element versus frequency as the
circuitry of PIG. 28 selects between each of two
different antenna feeds on the radiating element in
accordance with the present invention.
FIG. 30 is a circuit diagram showing how
illustrative switches and a passive antenna diplexer may
be used to selectively connect a radio-frequency (RF)
transceiver integrated circuit operating in three
frequency bands to two different antenna feeds in
accordance with the present invention.
FIG. 31 is a graph showing the return loss of
an illustrative radiating element versus frequency as the
circuitry of FIG. 30 selects between each of two
different antenna feeds on the radiating element in
accordance with the present invention.
FIG. 32 is a diagram showing how transmitting
and receiving subbands may be coupled to an antenna feed
using an illustrative switch in accordance with the
present invention.
FIG. 33 is a diagram showing how transmitting
and receiving subbands may be coupled to an antenna feed
using an illustrative duplexer in accordance with the
present invention.
FIG. 34 is a diagram showing how an
illustrative RF transceiver integrated circuit with five
bands can be selectively connected to two different
antenna feeds using switching circuitry made up of two
switches in accordance with the present invention.

FIG. 35 is a diagram showing the return loss of
an illustrative radiating element versus frequency as the
circuitry of FIG. 34 selects between each of the two
different antenna feeds in accordance with the present
invention.
FIG. 36 is a diagram showing how an
illustrative RF transceiver integrated circuit with four
bands can be selectively connected to two different
antenna feeds using two diplexers in accordance with the
present invention.
FIG. 37 is a diagram showing the return loss of
an illustrative radiating element versus frequency as the
switching circuitry of FIG. 36 selects between each of
the two different antenna feeds in accordance with the
present invention.
FIG. 38 is a diagram showing how an
illustrative RF transceiver integrated circuit with five
bands can be selectively connected to three different
antenna feeds using two diplexers and a duplexer in
accordance with the present invention.
FIG. 39 is a diagram showing the return loss of
an illustrative radiating element versus frequency as the
switching circuitry of FIG. 3 8 selects between each of
the three different antenna feeds in accordance with the
present invention.
FIG. 40 is a diagram of illustrative handheld
electronic device circuitry including control circuitry
that transmits and receives data, an RF module containing
an RF transceiver integrated circuit and switching
circuitry, and an antenna module having a multi-feed
radiating element in accordance with the present
invention.

FIG. 41 is a diagram showing how an
illustrative tester can be used to calibrate a circuit
board containing a multi-feed antenna in accordance with
the present invention.
FIG. 42 is a cross-sectional side view of an
illustrative RF switch connector for an RF module when
the RF module is in normal operation in accordance with
the present invention.
FIG. 43 is a cross-sectional side view of an
illustrative RF switch connector for an RF module when
the RF module is being calibrated using a test probe in
accordance with the present invention.
FIG. 44 is a flow chart of illustrative steps
involved in calibrating and using a handheld electronic
device having a multi-feed antenna in accordance with the
present invention.
Detailed Description
The present invention can relate to tunable
antennas for portable electronic devices, such as
handheld electronic devices. The invention can also
relate to portable devices that contain tunable antennas
and to methods for testing and using such devices and
antennas.
A tunable antenna in accordance with the
invention can have a radiating element with multiple
antenna feeds and a ground. The radiating element may be
formed using any suitable antenna structure such as a
patch antenna structure, a planar inverted-F antenna
structure, a helical antenna structure, etc.
The portable electronic devices may be small
portable computers such as those sometimes referred to as

ultraportables. With one particularly suitable
arrangement, the portable electronic devices are handheld
electronic devices. The use of handheld devices is
generally described herein as an example.
The handheld devices may be, for example,
cellular telephones, media players with wireless
communications capabilities, handheld computers (also
sometimes called personal digital assistants), remote
controllers, and handheld gaming devices. The handheld
devices of the invention may also be hybrid devices that
combine the functionality of multiple conventional
devices. Examples of hybrid handheld devices include a
cellular telephone that includes media player
functionality, a gaming device that includes a wireless
communications capability, a cellular telephone that
includes games and email functions, and a handheld device
that receives email, supports mobile telephone calls, and
supports web browsing. These are merely illustrative
examples. Any suitable device may include a tunable
multi-feed antenna, if desired.
Illustrative antenna and control circuitry 10
that may be used in a handheld device in accordance with
the invention is shown in FIG. 1. Circuitry 10 can
include control circuitry 28. Control circuitry 28 may
include one or more integrated circuits such as
microprocessors, microcontrollers, digital signal
processors, field programmable gate arrays, power
amplifiers, and application-specific integrated circuits.
Control circuitry 28 may also include passive RF
components such as duplexers, diplexers, and filters.
Control circuitry 28 may be mounted to one or
more printed circuit boards 30 or other suitable mounting

structures. Circuit board 30 may be, for example, a
dual-sided circuit board containing patterned conductive
traces.
Control circuitry 28 can send and receive RF
signals. The RF signals may be provided to an antenna
module. The antenna module can contain a radiating
element 12. Radiating element 12 may be formed from a
highly-conductive material, such as copper, gold, alloys
containing copper and other metals, high-conductivity
non-metallic conductors (e.g., high-conductivity organic-
based materials, high-conductivity superconductors,
highly-conductive liquids), etc. in the example of FIG.
1, the radiating element 12 can have a thin planar
profile, which facilitates placement of the radiating
element 12 within a handheld device. The use of a
radiating element with a planar structure is, however,
merely illustrative. The radiating element 12 may be
formed in any suitable shape.
In the FIG. 1 example, slot 14 can be formed in
radiating element 12, which increases the effective
length of the radiating element 12, while maintaining a
compact footprint. Radiating element 12 may be formed
using any suitable manufacturing technique. With one
suitable arrangement, the so-called foil stamping method
can be used to form radiating element 12. with foil
stamping techniques, a foil stamping machine is used to
generate numerous radiating elements from a thin copper
foil. Another suitable technique for forming radiating
element can involve printing or etching the antenna
pattern onto a fixed or flexible substrate. Flexible
substrates that may be used during these patterning
processes include so-called flex circuits (e.g., circuits

formed from metals such as copper that are layered on top
of flexible substrates such as polyimide). if desired,
other techniques may be used to form radiating elements
12.
The radiating element 12 can have a ground
signal terminal and two or more corresponding positive
signal terminals. The positive signal terminals can be
called antenna feeds. In the example of FIG. l,
radiating element 12 can have three elongated portions
16, 18, and 20. Elongated portion 16 may serve as
ground. Elongated portion 18 may serve as a first feed.
Elongated portion 20 may serve as a second feed. In
general, there may be any suitable number of feeds in the
antenna (e.g., two feeds, three feeds, four feeds, more
than four feeds, etc.).
Control circuitry 28 may include input-output
terminals, such as ground input-output terminal 32 and
positive input-output terminals 34 and 36. Conductive
paths such as paths 22, 24, and 26 may be used to
electrically connect the input-output terminals of
control circuitry 28 to radiating element 12. Paths 22,
24, and 26 may be patterned conductive traces (e.g.,
metal traces) formed on printed circuit board 30. Paths
24 and 26 may be used to electrically connect positive
input-output terminals 34 and 36 to elongated portions 18
and 20, respectively. A path such as path 2 2 may be used
to connect the ground input-output terminal 32 to the
ground portion 16 of radiating element 12. If desired,
the upper and lower portions of printed circuit board 30
may also be connected to ground. The elongated portions
16, 18, and 20 may be soldered or otherwise electrically
connected to paths 22, 24, and 26.

In the example of FIG. l, the elongated
portions 16, 18, and 20 are shown as being formed as an
integral portion of radiating element 12 and paths 22,
24. and 26 are shown as being formed from circuit board
traces. This is merely one suitable arrangement for
connecting the ground and feeds of the radiating element
12 to the circuitry of the handheld device. Other
suitable arrangement include contact arrangements based
on external spring-loaded pins and spring connectors.
Regardless of the particular type of arrangement that is
used to convey signals into and out of the radiating
element, the radiating element structure that is
associated with ground is commonly referred to as the
antenna's and radiating element's ground pin, ground
terminal, or ground and the radiating element, structure
that is associated with positive antenna signals is
commonly referred to as the antenna's and radiating
element's feed pin, feed terminal, or feed.
The antenna formed from radiating element 14
has a resonant frequency f0 at which it can transmit and
receive signals. The operating frequency range
surrounding f0 is sometimes referred to as the fundamental
band or fundamental operating frequency range of the
antenna. If, as an example, fo is at 850 MHz, the
antenna's fundamental frequency range can be used to
cover a 850 MHz communications band. Antennas also
generally resonate at higher frequencies that are
harmonics of f0. With this type of arrangement, an
antenna can cover two or more bands. For example, an
antenna may be designed to cover both the 850 MHz band
(using the antenna's fundamental frequency range centered
on fo) and the 1800 MHz band (using a harmonic frequency

range).
The bandwidth associated with an antenna's
operating frequency is influenced by the geometry of the
radiating element 12. Antennas that are compact tend to
have narrow bandwidths. Unless the bandwidth of the
antenna is widened (e.g., by increasing its physical
size), the antenna will not be able to cover nearby bands
without tuning.
As an example, consider the GSM cellular
telephone standard, which uses bands at 850 MHz, 900 MHz,
1800 MHz, and 1900 MHz. These bands may have bandwidths
of about 70-80 MHz (for the 850 MHz and 900 MHz bands),
170 MHz (for the 1800 MHz band), and 140 MHz (for the
1900 MHz band). Each band may contain two associated
subbands for transmitting and receiving data. For
example, in the 850 MHz band, a subband that extends from
824 to 84 9 MHz may be used for transmitting data from a
cellular telephone to a base station and a subband that
extends from 869 to 894 MHz may be used for receiving
data from a base station. The 850 MHz and 1900 MHz bands
may be used in countries such as the United States. The
900 MHz and 1800 MHz may be used in countries such as the
European countries.
A compact antenna that is designed to cover the
850 MHz band may have a harmonic that allows it to
simultaneously cover a higher band (e.g., 1900 MHz), but
a compact antenna that has a narrow bandwidth will not be
able to cover both the 850 MHz and 900 MHz bands unless
it is tuned.
In accordance with the present invention,
control circuitry 28 may be used to select between
different feeds to tune the antenna formed from radiating

element 12. When, for example, signals are transmitted
or received using ground terminal 32 and input-output
terminal 34, the antenna covers one band. When signals
are transmitted on received using ground terminal 32 and
input-output terminal 36, the antenna covers a different
band.
Each feed (and its associated ground) may serve
as an antenna port. An antenna such as an antenna formed
from radiating element 12 of FIG. 1 therefore can have
multiple ports and can be tuned by proper port selection.
The control circuitry 28 can be used to determine which
port is used. When access to a particular band is
desired, the control circuitry 2 8 ensures that the proper
port is active. By using multiple ports, a compact
antenna with potentially narrow resonances can be tuned
to cover all bands of interest.
A graph containing an illustrative plot of
return loss versus frequency for a tunable multi-port
antenna in accordance with the present invention is shown
in FIG. 2. Return loss is at a minimum at the antenna's
fundamental operating frequency range. No harmonic
frequency ranges are shown in FIG. 2.
When signals are transmitted and received
through a first antenna port (i.e., ground terminal 32,
path 22, and radiating element extension 16 and positive
input-output terminal 34, path 24, and radiating element
extension 18), the antenna covers the frequency range
centered at frequency fa, as shown by the solid line in
FIG. 2 When signals are transmitted and received through
a second antenna port (i.e., ground terminal 32, path 22,
and radiating element extension 16 and positive input-
output terminal 36, path 26, and radiating element

extension 20), the antenna covers the frequency range
centered at frequency fb, as shown by the dashed line in
PIG. 2. This allows the control circuitry 28 to tune the
antenna as needed, when it is desired to send or receive
data in the fa range, the control circuitry 28 uses the
first port. When the second port is used, the antenna's
response is tuned to higher frequencies, so that the
antenna covers a range of frequencies centered at fb.
By using intelligent port selection, the
coverage of an antenna can be extended to cover all
frequency bands of interest. Because compact radiating
elements tend to have small sizes, an antenna that is
tuned by selecting a desired antenna port can be made
more compact than would otherwise be possible, while
still ensuring that all desired bands are covered.
Moreover, tuning through the use of port selection can be
more efficient than antenna tuning through adjustable
capacitive loading schemes. Such capacitive loading
schemes introduce reactive losses, which reduce antenna
efficiency. An antenna with multiple feeds need not be
tuned using variable capacitive loading because tuning
can be performed through proper port selection.
A schematic diagram of an illustrative handheld
electronic device 38 containing a tunable multi-port
antenna is shown in FIG. 3. Handheld device 38 may be a
mobile telephone, a mobile telephone with media player
capabilities, a handheld computer, a game player, a
combination of such devices, or any other suitable
portable electronic device.
As shown in FIG. 3, handheld device 38 may
include storage 40. Storage 40 may include one or more
different types of storage such as hard disk drive

storage, nonvolatile memory (e.g., FLASH or electrically-
programmable -read-only memory), volatile memory (e.g.,
battery-based static or dynamic random-access-memory),
etc.
Processing circuitry 4 2 may be used to control
the operation of device 38. Processing circuitry 42 may
be based on a processor such as a microprocessor and
other suitable integrated circuits.
Input-output devices 44 may allow data to be
supplied to device 38 and may allow data to be provided
from device 38 to external devices. Input-output devices
can include user input-output devices 4 6 such as buttons,
touch screens, joysticks, click wheels, scrolling wheels,
touch pads, key pads, keyboards, microphones, cameras,
etc. A user can control the operation of device 38 by
supplying commands through user input devices 46.
Display and audio devices 48 may include liquid-crystal
display (LCD) screens, light-emitting diodes (LEDs), and
other components that present visual information and
status data. Display and audio devices 48 may also
include audio equipment such as speakers and other
devices for creating sound. Display and audio devices 48
may contain audio-video interface equipment such as jacks
for external headphones and monitors.
Wireless communications devices 50 may include
communications circuitry such as RF transceiver circuitry
formed from one or more integrated circuits, power
amplifier circuitry, passive RF components, antennas such
as the multiport antenna of FIG. 1, and other circuitry
for generating RF wireless signals. wireless signals can
also be sent using light (e.g., using infrared
communications).

The device 3 8 can communicate with external
devices such as accessories 52 and computing equipment
54, as shown by paths 56. Paths 56 may include wired and
wireless paths. Accessories 52 may include headphones
(e.g., a wireless cellular headset or audio headphones)
and audio-video equipment (e.g., wireless speakers, a
game controller, or other equipment that receives and
plays audio and video content). Computing equipment 54
may be a server from which songs, videos, or other media
are downloaded over a cellular telephone link or other
wireless link. Computing equipment 54 may also be a
local host (e.g., a user's own personal computer), from
which the user obtains a wireless download of music or
other media files.
As described in connection with FIG. 1, the
multiport antenna used in the handheld device can be
formed from any suitable radiating element 12. An
example of a radiating element 12 that is formed from a
rectangular patch antenna structure is shown in FIG. 4.
The antenna structure of FIG. 4 and the other radiating
element structures are preferably about one quarter of a
wavelength in size (e.g., several centimeters for most
cellular telephone wavelengths).
The radiating element 12 of FIG. 4 may have a
ground terminal 16, a first feed 18, a second feed 20,
and potentially more feeds (shown by dotted feed
structure 21). In general, any radiating element 12 may
have more than two feeds, but only the radiating element
12 of FIG. 4 shows the additional feeds to avoid overcomplicating
the drawings.
Different fundamental resonant frequencies are
associated with each of the different antenna ports and

are influenced by the geometry of the radiating element
12. As shown in FIG. 4, when feed 18 is used, there is
an inductive path in the antenna between feed 18 and
ground 16. This path is shown schematically by dotted
line 60. When feed 20 is used, there is a different
inductive path in the antenna, shown by dotted line 58.
Inductances L1 and L2 are associated with paths 60 and 58,
respectively. The inductance L2 is generally larger than
the inductance L1, so the port formed using feed 20
resonates at a higher frequency (e.g., frequency fb of
PIG. 2) than the port formed using feed 18 (e.g.,
frequency fa of FIG. 2).
An illustrative radiating element 12 that is
formed from a rectangular patch antenna structure
containing a slot 14 is shown in FIG. 5. Because of the
presence of slot 14, the antenna of FIG. 5 will exhibit
harmonics that are shifted with respect to the harmonics
of the patch antenna structure of FIG. 4. This allows
the antenna designer to place harmonics at desired
communications bands.
If desired, antenna ports may be formed on the
shorter side of a rectangular patch. An illustrative
structure of the type shown in FIG. 1 in which feeds have
been placed on the shorter size of the rectangular patch
is shown in FIG. 6.
Another illustrative radiating element 12 is
shown in FIG. 7. With the arrangement of FIG. 7, the
rectangular patch structure has a cut-away portion 68.
The cut-away portion 68 may be formed to accommodate a
cellular telephone camera, a button, a microphone,
speaker, or other component of the handheld device.
Ports may be formed on the long side of the element 12

(e.g., using ground 16 and feeds 18 and 20) or on the
short side of element 12 (e.g., using ground 16 and feeds
18a and 20a) . As shown in FIG. 8, the cut-away portion
68 need not be formed in the center of the radiating
element 12.
FIG. 9 shows how the sides of a radiating
element may be bent downwards. Portions of the radiating
element 12 such as portions 7 0 and 72 may be formed
during a foil stamping process or by using a flex
circuit. Portions 70 and 72 may serve as a fixed source
of capacitive loading. Using bent-down portions in this
type of arrangement tends to decrease the footprint of
the radiating element for a given operating frequency.
If desired, other forms of capacitive loading may be used
with radiating element. Capacitive loading can be used
with the patch antenna structure of PIG. 7 (as shown in
the example of FIG. 9) or with any other suitable
radiating element structure.
If desired, a radiating element 12 may be
formed from a flex circuit or other flexible substrate.
In the example of FIG. 10, radiating element 12 is formed
from a conductive element 62 that is formed in a
serpentine pattern on flex circuit substrate 64. After
the serpentine pattern is formed on substrate 64, the
substrate 64 is curled to form the cylindrical shape of
FIG. 10. The cylindrical antenna of FIG. 10 has a ground
16 and two feeds 18 and 20.
In the illustrative arrangement of FIG. 11,
radiating element 12 is formed from a patch antenna
having a serpentine slot 14. in general, one or more
slots of any suitable shape may be formed in the
radiating element 12.

FIG. 12 shows an illustrative arrangement for a
radiating element 12 that is based on an L-shaped planar
antenna arrangement. The radiating element 12 of FIG. 12
has a ground 16 and feeds 18 and 20.
In FIG. 13, the ground terminal 16 is formed
using a separate conductor from the conductive element
that contains feeds 18 and 20.
FIG. 14 shows an illustrative radiating element
12 that is formed from a separate ground element 16 and
serpentine element 66. Feeds 18 and 20 are formed at
different locations in the serpentine element 66.
The radiating element structures show in FIGS.
1 and 4-14 are merely illustrative. In general, any
suitable radiating element structures with multiple feeds
may be used.
As shown in FIG. 15, a printed circuit board
such as printed circuit board 30 of FIG. 1 may have an
upper surface of conductive material 74 and a lower
surface of conductive material 76 separated by an
insulating printed circuit board layer 78. The upper and
lower conductive surfaces may contain a patterned metal
such as copper. The lower surface may be relatively
unpatterned and may be used to form a ground plane.
Ground wires on the upper surface may be connected to the
lower surface ground plane using conductive vias 80.
When mounting the radiating element 12 to the printed
circuit board 30, the patterned conductors on the upper
surface of printed circuit board 30 may be used to form
electrical contact with the radiating element.
Electrical contact may be made using any
suitable electrical connecting structures. In the
example of FIG. 16, an elongated portion of radiating

element 12 (e.g., a ground or feed element of the type
shown in FIG. 1) is shown as forming a spring 82. When
the antenna is mounted in proximity to the circuit board,
the spring portion B2 presses against a conductive trace
84 on the upper surface 74 of circuit board 30. This
forms an electrical contact between trace 84 (which is
connected to control circuitry 28 of FIG. 1) and the
radiating element 12.
If desired, spring-loaded pins may be used to
make electrical contact between a radiating element 12
and circuit board 30. One commonly-available spring-
loaded pin is the so-called pogo pin. A cross-sectional
side view of a spring-loaded pin 86 is shown in FIG. 17.
Pin 86 has a reciprocating member 88 with a head portion
90 that reciprocates within a hollow cylindrical pin
housing 98. A spring 92 bears against the inner surface
94 of pin housing 98 and the upper surface 96 of head 90.
When member 88 is withdrawn within housing 98, spring 92
is compressed and biases reciprocating member 88 in
direction 100. This drives the tip 102 of member 88
against a conductive element such as a portion of a
circuit board or a radiating element.
FIG. 18 shows an arrangement in which a spring-
loaded pin 86 has been soldered to a radiating element 12
with solder 104. The tip 102 of the pin presses against
a conductor on the surface of circuit board 30.
In the arrangement of FIG. 19, the spring-
loaded pin 86 has been soldered to a circuit board 3 0 and
is pressing upward against the radiating element 12, so
that the tip 102 of reciprocating member 88-makes
electrical contact with the radiating element.
FIG. 20 shows an arrangement in which a spring

108 has been soldered to a circuit board 30 with solder
106. A portion 112 of radiating element 12 has been bent
downward. The portion 112 of radiating element 12 may be
formed during a metal foil stamping process (as an
example). As shown in FIG. 20, spring 108 is compressed
and bears against the portion 112, thereby forming
electrical contact between radiating element 12 and
circuit board 30.
The arrangement of FIG. 21 is similar to the
arrangement of FIG. 20, but involves forming an
electrical connection to a radiating element 12 that is
fabricated from a flex circuit. The radiating element 12
has a post 110. As shown in FIG. 21, a spring 108 that
has been soldered to circuit board 30 with solder 106
bears against post 110 to form electrical contact.
The pins and springs of FIGS. 18, 19, 20, and
21 need not be soldered to the circuit board or radiating
element 12. Arrangements in which the connecting
electrical structure is not soldered are said to be
floating. FIGS. 22 and 23 show floating pin arrangements
in which pin 86 forms an electrical connection between
radiating element 12 and circuit board 30. In the
arrangement of FIG. 22, the tip 102 of pin 86 presses
against the radiating element 12. In the arrangement of
FIG. 23, the tip 102 of pin 86 presses downward against a
conductor on circuit board 30.
Any suitable circuit architecture may be used
to interconnect the control circuitry 28 with the feeds
of the antenna and radiating element 12.
Consider, as an example, the arrangement of
FIG. 24. As shown in FIG. 24, an RF transceiver
integrated circuit 114 is connected to ground 16. RF

transceiver integrated circuit 114 is also connected to
two antenna feeds 18 and 20 using input-output data paths
115 and switching circuitry formed from switches 116.
Switches 116 may be formed from PIN diodes, high-speed
field-effect transistors (FETs), or any other suitable
switch components. The switches for each feed are
complementary and work in tandem. The state of each
switch is the inverse of the other. When switch SW1 is
on, switch SW2 is off and a first antenna port is active
while a second antenna port is inactive. when switch
SW1 is off, switch SW2 is on and the first antenna port
is inactive while the second antenna port is active.
Using this type of arrangement ensures that only one feed
is active at a time. feed1 is active and feed2 is
inactive when switch SW1 is on and switch SW2 is off.
Feed2 is active and feed1 is inactive when switch SW2 is
on and switch SW1 is off.
The graph of FIG. 25 shows the frequency
response of the radiating element 12 in two conditions.
The solid line shows the return loss of the radiating
element at its fundamental operating frequency range when
the first port is active. In this configuration, the
antenna is tuned so that it operates at the frequency fa.
The dashed line in FIG. 25 shows the return loss of the
radiating element when the second port is active, in
this configuration, the antenna is tuned so that it
operates at frequency fb.
In the arrangement of FIG. 26, switch SW1 may
handle two different bands (fa and fb), whereas switch SW2
may handle frequency band fc. Switch SW1 has three
states, in its first state, input-output signal path 118
is connected to feed1 and the antenna operates at

frequency fa. as shown in FIG. 27. In its second state,
input-output signal path 12 0 is connected to feed1 and
the antenna operates in band fb. As described in
connection with FIG. 24, switch SW2 is off whenever
switch SW1 is on. When it is desired to tune the
antenna, the control circuitry 2 8 places switch SW1 in a
third state in which lines 118 and 12 0 are disconnected
from feed1 (i.e.-, switch SW1 is off). When switch SW1 is
turned off, switch SW2 is turned on, so the antenna
operates at shifted fundamental frequency fc (FIG. 27).
As shown in FIGS. 28 and 29, passive RF
components such as duplexers and diplexers may be used to
couple RF transceiver 114 to the antenna feeds. A
duplexer can be used to combine or separate RF signals
that are in adjacent bands (e.g., 850 MHz and 900 MHz).
A diplexer can be used to combine or separate RF signals
that are in distant bands (e.g., 850 MHz and 1800 MHz).
As shown in FIG. 28, duplexer 122 may be
coupled between data paths 118 and 12 0 and switch SW1.
Switch SW2 is coupled between data path 126 and feed2.
When it is desired to use feed1, switch SW1 is turned on
and switch SW2 is turned off. This tunes the antenna so
that it operates according to the solid line of FIG. 29.
In this state, RF transceiver 114 can use paths 118 and
120 to transmit and receive in either frequency band fa or
frequency band fb, because the radiating element 12 of the
antenna is designed to have a sufficiently large
bandwidth in its fundamental operating frequency range to
handle the adjacent bands fa and fb. When it is desired
to tune the antenna by using feed2, switch SW1 is turned
off and switch SW2 is turned on. In this state, path 126
is connected to feed2 and transceiver 114 can transmit

and receive signals using band fc, as shown by the dotted
line in FIG. 29.
In the arrangement of FIG. 30, a diplexer 124
is used in place of a duplexer. The radiating element 12
in this scenario is designed to have a harmonic at fb-
Because a diplexer 124 is being used, the signals
associated with paths 118 and 120 must be more widely
separated than in the duplexer arrangement of FIG. 28.
As shown by the solid line in FIG. 31, when feed1 is
switched into use by turning on SW1 and turning off SW2,
transceiver 114 can use paths 118 and 120 to transmit and
receive in either fundamental frequency band fa or
harmonic frequency band fb. When it is desired to tune
the antenna by using feed2, switch SW1 is turned off and
switch SW2 is turned on. In this state, path 126 is
connected to feed2 and transceiver 114 can transmit and
receive signals using band fc, as shown by the dotted line
in FIG. 31.
The bands used in GSM communications each have
two subbands, one of which contains channels for
transmitting data and the other of which contains
channels for receiving data. As shown in FIG. 32, a
switch 116 can be used to connect an appropriate transmit
or receive data path to its associated feed 128. Paths
118a and 118b are connected to the RF transceiver. In
GSM communications, signals are either transmitted or are
received. Simultaneous transmission and reception is not
permitted. When the RF transceiver has data to transmit,
switch 116 connects the transmit line 118a to feed 128.
In receive mode, the switch 116 is directed to connect
feed 128 to path 118b. When it is desired to inactivate
the feed 128, switch 116 may be turned off. In the

example of FIG. 32, paths 118a and 118b are labeled 850T
(850 MHz transmit) and 8S0R (850 MHz receive). The same
principal applies to all GSM bands. The input-output
data paths connected to the RF transmitter 114 in FIGS.
24, 26, 28, and 30 are shown as single bidirectional
paths rather than as separate transmit and receive paths
to avoid over-complicating the drawings.
An arrangement in which a duplexer 122 may be
used to couple an RF transceiver to a feed 128 is shown
in FIG. 33. When incoming data is received on feed 128
or when outgoing data is being transmitted, switch 116 is
on. Switch 116 is off when it is desired to tune the
antenna by using a different feed. Duplexer 12 2 is
frequency sensitive. Incoming data (e.g., on the 850R
subband) is routed to line 118b by the passive RF
components in duplexer 122. When outgoing data is
transmitted on line 118a, duplexer 12 2 routes those
signals to line 128 via switch 116.
When architectures of the type shown in FIGS.
24, 26, 28, and 30 are used for GSM-type communications,
an active subband switching arrangement of the type shown
in FIG. 32 or a passive subband routing arrangement of
the type shown in FIG. 33 may be used. In either case,
switching circuitry 116 is used to ensure that the
appropriate antenna feed is active.
In some communications protocols such as those
based on code division multiple access (CDMA) technology,
signals can be transmitted and received simultaneously.
There is therefore no need for a switch to actively
switch between transmit and receive bands. Examples of
communications schemes that use CDMA technology include
CDMA cellular telephone communications and 3G data

communications over the 2170 MHz band (commonly referred
to as UMTS or Universal Mobile Telecommunications
System). With CDMA-based arrangements, a duplexer
arrangement of the type shown in FIG. 33 may be used to
separate transmitting and receiving frequencies from each
other.
Some handheld devices need to cover many bands.
An example of an arrangement that may be used to cover
five bands (e.g., the four GSM bands plus the UMTS band)
using a two port antenna is shown in FIG. 34. A graph
showing the placement of each of the bands is shown in
FIG. 35. The antenna is designed to have a fundamental
operating frequency range 128 at about 850-900 MHz and a
harmonic operating frequency range 13 0 at about 1800-
1900. When switch SW1 is on and switch SW2 is off, feed1
is active and the antenna's response is as shown by the
solid line in FIG. 35. The antenna is designed to have a
relatively broad bandwidth at its fundamental and
harmonic operating frequencies. As a result, the antenna
covers both the 850 MHz and 900 MHz GSM bands in the
fundamental operating frequency range 128 and covers both
the 1800 MHz and 1900 MHz GSM bands using the harmonic
operating frequency range 130. When switch SW2 is on and
switch SWl is off, feed 2 is active and the antenna is
tuned. This shifts the harmonic operating frequency
range 13 0 to a higher frequency, so that it covers the
UMTS band at 2170 MHz.
An example of an arrangement that may be used
to cover four bands (e.g., the four GSM bands) using a
two port antenna is shown in FIG. 36. Diplexers 124 are
used to couple RF transceiver 114 to switching circuitry
116. One diplexer 124 handles the 850 MHz and 1800 MHz

bands while the other diplexer 124 handles the 900 MHz
and 1900 MHz bands. A graph showing the placement of
each of the bands is shown in FIG. 37. The antenna is
designed to have a fundamental operating frequency range
128 at about 850 MHz and a harmonic operating frequency
range 130 at about 1800. When switch SW1 is on and
switch SW2 is off, feed1 is active and the antenna's
response is as shown by the solid line in FIG. 37. The
antenna has a narrow bandwidth that covers a single band
at each resonant frequency.
As shown by the solid line in FIG. 37, when
feed1 is used, the antenna can cover both the 850 MHz and
1800 MHz bands. When it is desired to tune the antenna,
switches 116 are adjusted so that feed2 is used. This
shifts both the fundamental operating range 128 and the
harmonic operating frequency range 13 0 to higher
frequencies, so as to cover the 900 MHz and 190 0 MHz
bands, respectively, as shown by the dashed line in FIG.
37.
An example of an arrangement that may be used
to cover five bands (e.g., the four GSM bands and the
UMTS band) using a three port antenna is shown in FIG.
38. Diplexers 124 are used to couple RF transceiver 114
to switching circuitry 116. One diplexer 124 handles the
850 MHz and 1800 MHz bands while the other diplexer 124
handles the 900 MHz and 1900 MHz bands. The placement of
each of the bands is shown in the graph of FIG. 39. When
feed1 is used, the antenna is has a fundamental operating
frequency range 128 at about 850 MHz and a harmonic
operating frequency range 130 at about 1800 MHz. when
switch SW1 is on and switches SW2 and SW3 are off, feed1
is active and the antenna's response is as shown by the

solid line in FIG. 39.
As shown by the solid line in FIG. 39, when
feed1 is used, the antenna covers both the 8 50 MHz and
1800 MHz bands. Due to the relatively narrow bandwidth
of the antenna, adjacent bands are not covered without
tuning. When it is desired to tune the antenna to cover
the 900 MHz and 1900 MHz bands, switches 116 are adjusted
so that feed2 is used. This shifts both the fundamental
operating range 128 and the harmonic operating frequency
range 130 to higher frequencies, so as to cover the 900
MHz and 1900 MHz bands, respectively, as shown by the
dashed line in FIG. 39.
When it is desired to tune the antenna to cover
the 2170 MHz band, switches 116 are adjusted so that
feed3 is switched into use. As a result, the fundamental
operating range 128 and the harmonic operating frequency
range 130 are shifted to higher frequencies. With this
antenna tuning configuration, the harmonic operating
frequency range 130 covers the 2170 MHz band, as shown by
the dot-and-dashed line in FIG. 39.
FIG. 40 shows details of an arrangement of the
type described in FIGS. 34 in which five bands are
covered (e.g., the four GSM bands and the UMTS band)
using two antenna ports.
Processing circuitry 42 can generate data to be
transmitted and can provide this data to RF module 132 in
wireless communications circuitry 50 using a path such as
path 140. Data that is received by the handheld device
may be routed from RF module 132 to processing circuitry
42 via path 142. Transceiver 114 can be coupled to
radiating element 12 in antenna module 134 via feed1,
feed2, and ground. Switching circuitry 116 can be used

to regulate which antenna port is active. Switch sw1 can
be used to select a desired GSM signal path to connect to
feed1 when feed1 is active and is used to disconnect
feed1 from the RF transmitter when feed1 is inactive.
Switch SW2. which is on when switch SWl is inactive, can
used to seletively activate feed2. Switch SW2 can
receive transmitted signals from RF transceiver 114 and
can deliver received signals to RF transceiver 114
through duplexer 122, which can handle the transmit and
receive subbands for a 2170 MHz UMTS band.
A power amplifier integrated circuit 136 may be
used to boost outgoing signal levels. Power amplifier
integrated circut 136 contains power amplifiers 138. The
power amplifiers may be provided as separate integrated
circuits if desired.
A testing arrangement that may be used to
calibrate an RF module 132 during the process of
manufacturing a handheld device 38 is shown in FIG. 41.
During testing, tester 144 can apply power and control
signals to processing circuitry 42 using a path such as
path 14 7. The control signals may direct the processing
circuitry 42 to transmit signals to antenna module 134.
Each feed can be calibrated in turn. Tester 144 has a
cable and test probe that can be connected to either RF
switch connector 152 (when the cable and probe are in the
position indicated by line 148) or RF switch connector
156 (when the cable and probe are in the position
indicated by line 150). During testing, the probe taps
into the signals that would otherwise be transmitted over
antenna module 134.
RF switch connectors 152 and 156 have two
operating conditions. A cross-section of an illustrative

RF switch connector 166 is shown in FIGS. 42 and 43.
When no test probe is inserted, as shown in FIG. 42,
input 160 is connected to output 162 via conductor 164.
When the tip of a test probe 168 is inserted into switch
connector 166, conductor 164 is pressed downwards, which
opens the circuit between conductor 164 and output 162
and electrically connects input 160 to the test probe
168.
RF switch connector 152 may be used to tap into
signals that would normally pass from data path 154 to
feed1, whereas RF switch connector 156 may be used to tap
into signals that would normally pass from data path 158
to feed2. During calibration, tester 144 measures the
signal strenth received on each feed for a variety of
output power settings. Using curve fitting techniques,
tester 144 determines which calibration settings should
be stored in the circuitry 10. The calibration settings
are loaded into non-volatile memory 40 such as flash
memory over a path such as path 146. Later, during
normal operation, processing circuitry 42 uses the stored
calibration settings to make calibrating adjustments to
the output signal levels of the RF module 132.
Illustrative steps involved in testing and
fabricating handheld devices with tunable multi-port
antennas are shown in FIG. 44.
At step 170, a circuit board assembly
containing the RF moudule 132 and antenna module 134 can
be fabricated.
At step 172, tester 144 of FIG. 41 may send
control signals to processing circuitry 42 via path 147.
The control signals direct the processing circuitry 42 to
use transceiver 114 and switching circuitry 116 to

transmit suitable test signals to the antenna on feeds IB
and 20. Each feed is excercised separately. To ensure
accurate measurements, test signals may be transmitted
using several different power settings while tester 144
gathers associated test measurements.
At step 174, the tester 144 can process the
test measurements (e.g., using curve-fitting routines)
and generates corresponding calibration settings. The
calibration settings indicate what adjustments need to be
made by RF module 132 during normal operation to ensure
that the transmitted RF power levels are accurate.
The tester 144 can store the calibration
information in memory 40 at step 176. With one suitable
arrangement, the calibration information is stored in a
non-volatile memory such as a flash memory to ensure that
the calibration information will be retained in the event
of a loss of power by the handheld electronic device 38.
During steps 178 and 180, the handheld
electronic device 38 may be used by a user to place
cellular telephone calls, to upload or download data over
a 36 link, or to otherwise wirelessly transmit and
receive data.
During step 178, the processing circuitry 42
(FIG. 41) retrieves the calibration settings data from
memory 40 and uses the retrieved calibration settings to
adjust the power output of the handheld device so that
the output power is calibrated. The processing circuitry
42 calibrates each port separately, so the output power
is accurate regardless of which antenna port is being
used.
During step 180, the user can transmit and
receive data using the antenna. The processing circuitry

42 tunes the antenna as needed by selecting an
appropriate antenna feed using switching circuitry 116.
The foregoing is merely illustrative of the
principles of this invention and various modifications
can be made by those skilled in the art without departing
from the scope and spirit of the invention.

What is Claimed is:
1. A tunable multiport handheld electronic
device antenna, comprising:
a radiating element;
a ground terminal that is electrically
connected to the radiating element; and
at least first and second antenna feeds,
wherein the first antenna feed is electrically connected
to the radiating element at a first location, wherein the
second antenna feed is electrically connected to the
radiating element at a second location that is different
from the first location, wherein the first antenna feed
and the ground form a first antenna port, and wherein the
second antenna feed and the ground form a second antenna
port.
2. The tunable multiport handheld electronic
device antenna defined in claim l wherein the radiating
element comprises a patch antenna structure.
3. The tunable multiport handheld electronic
device antenna defined in claim 1 wherein the radiating
element comprises a metal antenna structure without
adjustable capacitive loading.
4. The tunable multiport handheld electronic
device antenna defined in claim 1 wherein the radiating
element comprises first, second, and third integral
elongated portions, wherein the first elongated portion
forms the ground, wherein the second elongated portion
forms the first feed, and wherein the third elongated
portion forms the second feed.

5. The tunable multiport handheld electronic
device antenna defined in claim 1 wherein the radiating
element comprises metal and is configured to operate at a
frequency range associated with a first cellular
telephone band when the first port is used and is
configured to operate at a frequency range associated
with a second cellular telephone band that is different
from the first cellular telephone band when the second
port is used.
6. A handheld electronic device comprising:
storage that stores data;
processing circuitry coupled to the
storage that generates data for wireless transmission and
that processes wirelessly-received data; and
wireless communications circuitry that
communicates with the processing circuitry, wherein the
wireless communications circuitry contains a tunable
multiport antenna containing a ground, a first antenna
feed, and a second antenna feed, wherein the processing
circuitry tunes the antenna by selecting whether to use
the first antenna feed or the second antenna feed in
wirelessly transmitting and receiving data.
7. The handheld electronic device defined in
claim 6 wherein the wireless communications circuitry
comprises:
a radio - frequency transceiver having a
plurality of associated paths, each path being configured
to carry signals associated with a separate
communications band; and

switching circuitry that selectively
connects the first feed or the second feed to an active
one of the plurality of associated paths to tune the
antenna so that the antenna operates at the
communications band associated with the active path.
8. The handheld electronic device defined in
claim 6 wherein the wireless communications circuitry
comprises:
a radio-frequency transceiver having a
plurality of associated paths, each path being configured
to carry signals associated with a respective one of a
set of at least five different communications bands; and
switching circuitry that selectively
connects the first feed or the second feed to an active
one of the plurality of associated paths to tune the
antenna so that the antenna operates at the
communications band associated with the active path,
wherein the antenna transmits and receives signals in a
fundamental frequency range and a harmonic frequency
range, wherein when the first feed is connected, the
antenna's fundamental frequency range is used to transmit
and receive signals associated with a first one of the
five bands and a second one of the five bands and the
antenna's harmonic frequency range is used to transmit
and receive signals associated with a third one of the
five bands and a fourth one of the five bands, and
wherein when the second feed is connected, the antenna's
harmonic frequency range is used to transmit and receive
signals associated with a fifth one of the five bands.
9. The handheld electronic device defined in

claim 6 wherein the wireless communications circuitry
comprises:
a radio-frequency transceiver having a
plurality of associated paths, each path being configured
to carry signals associated with a respective one of a
set of at least five different communications bands; and
switching circuitry that selectively
connects the first feed or the second feed to an active
one of the plurality of associated paths to tune the
antenna so that the antenna operates at the
communications band associated with the active path,
wherein the antenna transmits and receives signals in a
fundamental frequency range and a harmonic frequency
range, wherein when the first feed is connected, the
antenna's fundamental frequency range is used to transmit
and receive signals associated with a first one of the
five bands and a second one of the five bands and the
antenna's harmonic frequency range is used to transmit
and receive signals associated with a third one of the
five bands and a fourth one of the five bands, and
wherein when the second feed is connected, the antenna's
harmonic frequency range is used to transmit and receive
signals associated with a fifth one of the five bands,
wherein the second band has a higher frequency than the
first band, wherein the third band has a higher frequency
than the second band, wherein the fourth band has a
higher frequency than the third band, wherein the fifth
band has a higher frequency than the fourth band, wherein
the first, second, third, and fourth communications bands
are cellular telephone bands and wherein the fifth band
is a data band.

10. The handheld electronic device defined in
claim 6 wherein the wireless communications circuitry
comprises:
a radio-frequency transceiver having a
plurality of associated paths, each path being configured
to carry signals associated with a respective one of a
set of at least five different communications bands; and
switching circuitry that selectively
connects the first feed or the second feed to an active
one of the plurality of associated paths to tune the
antenna so that the antenna operates at the
communications band associated with the active path,
wherein the antenna transmits and receives signals in a
fundamental frequency range and a harmonic frequency
range, wherein when the first feed is connected, the
antenna's fundamental frequency range is used to transmit
and receive signals associated with a first one of the
five bands and a second one of the five bands and the
antenna's harmonic frequency range is used to transmit
and receive signals associated with a third one of the
five bands and a fourth one of the five bands, and
wherein when the second feed is connected, the antenna's
harmonic frequency range is used to transmit and receive
signals associated with a fifth one of the five bands,
wherein the first band is centered at about 850 MHz,
wherein the second band is centered at about 900 MHz,
wherein the third band is centered at about 1800 MHz,
wherein the fourth band is centered at about 1900 MHz,
and wherein the fifth band is centered at about 2170 MHz.
11. Tunable multiport antenna circuitry
comprising:

a radiating element;
a circuit board having a ground conductive
path and first and second antenna feed conductive paths;
a ground electrical connecting structure
that connects the ground conductive path to the radiating
element and serves as a ground terminal for the radiating
element;
a first feed electrical connecting
structure that electrically connects the first feed
conductive path on the circuit board to the radiating
element at a first location and serves as a first feed
terminal for the radiating element; and
a second feed electrical connecting
structure that electrically connects the second feed
conductive path on the circuit board to the radiating
element at a second location distinct from the first
location and serves as a second feed terminal for the
radiating element.
12. The tunable multiport circuitry defined in
claim 11 wherein at least one of the ground electrical
connecting structure, the first feed electrical
connecting structure, and the second feed electrical
connecting structure comprises a spring-loaded pin.
13. The tunable multiport circuitry defined in
claim 11 wherein at least one of the ground electrical
connecting structure, the first feed electrical
connecting structure, and the second feed electrical
connecting structure comprises a piece of bent conductor
that serves as a spring.

14. The tunable multiport circuitry defined in
claim 11 wherein at least one of the ground electrical
connecting structure, the first feed electrical
connecting structure, and the second feed electrical
connecting structure comprises a piece of bent conductor
formed as an integral part of the radiating element that
serves as a spring and that is soldered to one of the
conductive paths on the circuit board.
15. The tunable multiport circuitry defined in
claim n wherein the circuit board has a third feed
conductive path, the circuitry further comprising:
a third feed electrical connecting
structure that electrically connects the third feed
conductive path on the circuit board to the radiating
element at a third location distinct from the first and
second locations and that serves as a third feed terminal
for the radiating element.
16. A method for calibrating and using a
tunable multiport antenna in a handheld electronic
device, comprising:
fabricating a circuit board assembly that
contains a radio-frequency module, a radiating antenna
element that is connected to the radio-frequency module
with a ground and at least first and second antenna
feeds, processing circuitry, and non-volatile memory,
wherein the radio-frequency module contains at least a
first radio-frequency switch connector for tapping into
the first feed with a test probe and a second radio-
frequency switch connector for tapping into the second
feed with the test probe; and

sending control signals to the processing
circuitry from a tester while measuring output signal
powers for the first and second antenna feeds using the
first and second radio-frequency switch connectors,
wherein only a single one of the first and second antenna
feeds is active at a given time.
17. The method defined in claim 16 further
comprising:
determining calibration settings based on
the measured output signal powers; and
storing the calibration settings in the
non-volatile memory.
18. The method defined in claim 16 further
comprising:
determining calibration settings based on
the measured output signal powers;
storing the calibration settings in the
non-volatile memory; and
transmitting and receiving data through
the antenna radiating element using the calibration
settings.
19. A method for using a tunable multiport
antenna in a handheld electronic device, wherein the
tunable multiport antenna has a first antenna port formed
from a ground and a first antenna feed and has a second
antenna port formed from a ground" and a second antenna
feed, wherein the handheld electronic device comprises a
radio-frequency transceiver having associated data paths
each of which carries signals for a different

communications band, and wherein the handheld electronic
device comprises switching circuitry that is coupled
between the radio-frequency transceiver and the first and
second antenna feeds, the method comprising:
adjusting the switching circuitry to
activate a single selected one of the first and second
antenna ports while deactivating the other of the first
and second antenna ports; and
conveying signals between the transceiver
and the single selected antenna port using one of the
data paths and the antenna feed and ground of the single
selected antenna port.
20. The method defined in claim 19 wherein the
handheld electronic device comprises non-volatile memory
in which calibration settings for the first and second
antenna ports have been stored and wherein conveying the
signals comprises:
transmitting signals from the transceiver
using the calibration settings, wherein when the first
antenna port is activated by the switching circuitry, the
tunable multiport antenna transmits and receives signals
in a fundamental frequency range containing at least a
first communications band and transmits and receives
signals over a harmonic frequency range containing at
least a second communications band, wherein when the
second antenna port is activated by the switching
circuitry, the tunable multiport antenna transmits and
receives signals in the harmonic frequency range
containing at least a third communications band, and
wherein the second and third communications bands are
different.

21. Wireless communications circuitry
comprising:
a tunable multiport radiating element
having a ground terminal and at least first and second
feed terminals, wherein the first feed terminal and the
ground terminal form a first antenna port, wherein the
second feed terminal and the ground terminal form a
second antenna port;
a transceiver having a number of
associated signal input-output paths that convey signals
to and from the antenna; and
switching circuitry that tunes the tunable
multiport radiating element by selectively activating the
first port and the second port, wherein the switching
circuitry activates the first port by connecting a first
one of the input-output paths to the first feed while
disconnecting the second feed from the input-output paths
and wherein the switching circuitry activates the second
port by connecting a second one of the input-output paths
to the second feed while disconnecting the first feed
from the input-output paths.
22. The wireless communications circuitry
defined in claim 21 wherein the radiating element is
configured to operate over a fundamental frequency range
and a harmonic frequency range that is higher than the
fundamental frequency range and wherein the signal input-
output paths comprise:
a first input-output path that is
configured to transmit and receive signals for a first
communications band;

a second input-output path that is
configured to transmit and receive signals for a second
communications band that is different than the first
communications band; and
a third input-output path that is
configured to transmit and receive signals for a third
communications band that is different than the first and
second communications bands, wherein when the first port
is active, the first communications band lies within the
fundamental frequency range and the second communications
band lies within the harmonic frequency range and wherein
when the second port is active, the third communications
band lies within the harmonic frequency range.
23. The wireless communications circuitry
defined in claim 21 wherein the radiating element is
configured to operate over a fundamental frequency range
and a harmonic frequency range that is higher than the
fundamental frequency range, the wireless communications
circuitry further comprising power amplifiers that
amplify at least some of the signals on the input-output
paths and at least one radio-frequency duplexer, wherein
the signal input-output paths comprise:
a first input-output path that is
configured to transmit and receive signals for a first
communications band;
a second input-output path that is
configured to transmit and receive signals for a second
communications band that is different than the first
communications band; and
a third input-output path that is
configured to transmit and receive signals for a third

communications band that is different than the first and
second communications bands, wherein when the first port
is active, the first communications band lies within the
fundamental frequency range and the second communications
band lies within the harmonic frequency range, wherein
when the second port is active, the third communications
band lies within the harmonic frequency range, and
wherein the duplexer is coupled within the third input-
output path between the transceiver and the switching
circuitry.
24. The wireless communications circuitry
defined in claim 21 wherein the radiating element is
configured to operate over a fundamental frequency range
and a harmonic frequency range that is higher than the
fundamental frequency range, the wireless communications
circuitry further comprising power amplifiers that
amplify at least some of the signals on the input-output
paths and at least one radio-frequency duplexer, wherein
the signal input-output paths comprise:
a first input-output path that is
configured to transmit and receive signals for a first
communications band;
a second input-output path that is
configured to transmit and receive signals for a second
communications band that is different than the first
communications band;
a third input-output path that is
configured to transmit and receive signals for a third
communications band that is different than the first and
second communications bands, wherein the duplexer is
coupled within the third input-output path between the

transceiver and the switching circuitry;
a fourth input-output path that is
configured to transmit and receive signals for a fourth
communications band that is different than the first,
second, and third communications bands; and
a fifth input-output path that is
configured to transmit and receive signals for a fifth
communications band that is different than the first,
second, third, and fourth communications bands, wherein
when the first port is active, the first and fourth
communications bands lie within the fundamental frequency
range and the second and fifth communications bands lie
within the harmonic frequency range and wherein when the
second port is active, the third communications band lies
within the harmonic frequency range.
25. The wireless communications circuitry
defined in claim 21 wherein the radiating element is
configured to operate over a fundamental frequency range
and a harmonic frequency range that is higher than the
fundamental frequency range, the wireless communications
circuitry further comprising power amplifiers that
amplify at least some of the signals on the input-output
paths and at least one radio-frequency duplexer, wherein
the signal input-output paths comprise:
a first input-output path that is
configured to transmit and receive signals for a first
communications band;
a second input-output path that is
configured to transmit and receive signals for a second
communications band that is different than the first
communications band;

a third input-output path that is
configured to transmit and receive signals for a third
communications band that is different than the first and
second communications bands, wherein the duplexer is
coupled within the third input-output path between the
transceiver and the switching circuitry;
a fourth input-output path that is
configured to transmit and receive signals for a fourth
communications band that is different than the first,
second, and third communications bands; and
a fifth input-output path that is
configured to transmit and receive signals for a fifth
communications band that is different than the first,
second, third, and fourth communications bands and that
is associated with a data service, wherein when the first
port is active, the first and fourth communications bands
lie within the fundamental frequency range and the second
and fifth communications bands lie within the harmonic
frequency range, wherein when the second port is active,
the third communications band lies within the harmonic
frequency range, and wherein the first, second, third,
and fourth communications bands each include non-
overlapping transmit and receive subbands.

A compact tunable antenna for a handheld electronic device and methods for calibrating and using compact tunable
antennas are provided. The antenna can have multiple ports. Each port can have an associated feed and ground. The antenna design
can be implemented with a small footprint while covering a large bandwidth. The antenna can have a radiating element formed from
a conductive structure such as a patch or helix. The antenna can be shaped to accommodate buttons and other components in the
handheld device. The antenna may be connected to a printed circuit board in the handheld device using springs, pogo pins, and other
suitable connecting structures. Radio- frequency switches and passive components such as duplexers and diplexers may be used to
couple radio- frequency transceiver circuitry to the different feeds of the antenna. Antenna efficiency can be enhanced by avoiding
the use of capacitive loading for antenna tuning.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=G4zGcjeLiTVPBcWdZuimSQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

269165

Indian Patent Application Number

599/KOLNP/2009

PG Journal Number

41/2015

Publication Date

09-Oct-2015

Grant Date

06-Oct-2015

Date of Filing

16-Feb-2009

Name of Patentee

APPLE INC.

Applicant Address

1 INFINITE LOOP M/S 40-PAT, CUPERTINO, CALIFORNIA

Inventors:

#	Inventor's Name	Inventor's Address
1	ZHANG, ZHIJUN	1 INFINITE LOOP M/S 40-PAT, CUPERTINO, CALIFORNIA 95014
2	CABALLERO, RUBEN	1 INFINITE LOOP M/S 40-PAT, CUPERTINO, CALIFORNIA 95014

PCT International Classification Number

H01Q 1/24,H01Q 9/04

PCT International Application Number

PCT/US2007/014078

PCT International Filing date

2007-06-14

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	11/516,433	2006-09-05	U.S.A.