Title of Invention	"A METHOD FOR CONTROLLING THE RADIATION PATTERN OF AN ANTENNA MEANS, AN ANTENNA SYSTEM AND A RADIO COMMUNICATION DEVICE"
Abstract	A method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater than 1, and being adapted for receiving or receiving and transmitting RF signals, said method comprising the steps of: measuring at least one property of at least one received signal from at least one of said radiating elements, and controlling at least one of the parameters phase (Qn) and amplitude (An) for received signals and/or signals to be transmitted for at least one of the radiating elements as a response to the measured property of said received signal. a response to the measured property of said received signal.

Title of Invention

"A METHOD FOR CONTROLLING THE RADIATION PATTERN OF AN ANTENNA MEANS, AN ANTENNA SYSTEM AND A RADIO COMMUNICATION DEVICE"

Abstract

A method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater than 1, and being adapted for receiving or receiving and transmitting RF signals, said method comprising the steps of: measuring at least one property of at least one received signal from at least one of said radiating elements, and controlling at least one of the parameters phase (Qn) and amplitude (An) for received signals and/or signals to be transmitted for at least one of the radiating elements as a response to the measured property of said received signal. a response to the measured property of said received signal.

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] "A METHOD FOR CONTROLLING THE RADIATION PATTERN OF AN ANTENNA MEANS, AN ANTENNA SYSTEM AND A RADIO COMMUNICATION DEVICE" ALLGON AB, a Swedish Body Company, of Antennvagen 6, S-187 80 Taby, Sweden The following specification particularly describes and ascertain the nature of the invention and the manner in which it is to be performed :- FIELD OF THE INVENTION The invention relates to a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater signals. It also relates to an antenna system for transmission/reception of RF. signals, comprising N helically configured antenna elements, where N is an integer greater than 1, and being adapted for transmitting and/or receiving RF signals. The invention further relates to a radio communication device incluing such an antenna system. BACKGROUND OF THE INVENTION AND RELATED ART For antenna applications where a hemispherical coverage with circular polarization is desired, a quadrifilar helix antenna (QHA) can be used. An advantage of the QHA is the ability to shape the radiation pattern from a narrow axial beam to a very broad beam covering almost the entire sphere. The pattern can also be designed to have peaks and dips at certain angles. This is done by exciting different radiation modes, axial and/or radial ones. A QHA consists of four wires wound around a cylindrical or conical surface with a constant pitch angle. Usually, when space is limited, the choice is a narrow and short cylindrical QHA, having three degreed of freedom (e.g. diameter, pitch angle, length) . Allowing the surface to be conical gives one extra decree of freedom, and can significantly increase the bandwidth. Modifications can be added to the helices to achieve certain features. Each helix can for example be split in two, the halves having different lengths, for double tuning. Also, if the circumference is large enough, the helices can be meandered to reduce the length of the antenna. A QHA is fed at either the bottom or the top end by means of a feed network. Several guadrifilar helix antennas (QHA), are known from patents and published patent applications. A large number of these disclose quadrifilar antenna structures for circularly-polarized radio signals. See, for example, WO 98/28815, WO 97/06579, WO 97/11507, US 5,191,352, US 5,255,005, and US 5,541,617. In all those antenna structures, helical elements are fed with constant amplitude and constant phase-shift between the helical elements. Figure 1 shows a typical radiation pattern of such an antenna structure mounted to a portable radio¬telephone. The radiation pattern exhibits a main lobe M directed upwards and, in most cases, a minor back lobe B directed downwards when fed with a progressive phase-shift adapted to the rotational directions of the helical elements. Between the lobes, the radiation pattern has a blind sector or null BS, where reception/transmission cannot be performed. In order to direct the main antenna lobe towards a transmitter/receiver (e.g. a satellite) with which a radio communication device is to communicate, telephones having an antenna structure mounted to the telephone housing with a pivot joint have for example been provided. The orientation of the antenna structure can then be adjusted manually for good signal transmission/reception. New adjustments can take place when the transmitter/receiver has changed location or when the telephone has been moved. An example of an antenna structure mounted with a pivoting joint to a telephone is disclosed in US-A-5,628,057. In EP 0881782 a mobile station, in a mobile communication system, having a plurality of antenna elements is described. A signal received by an antenna element is demodulated and the phase and power of the signal is detected. On the basis of the results a control device calculates the phase and the power of a transmission signal, which is transmitted to each antenna element. The distance between each antenna element is greater than X/2, which makes the antenna arrangement rather large, not suitable for handheld communication applications. Each antenna element is provided with a receiver and transmitter which are space consuming and thus also makes it not suitable for handheld communication applications. SUMMARY OF THE INVENTION In this disclosure it is to be understood that the antenna system of the invention is operable to receive or receive and transmit radio signals. Even if a term is used herein that suggests one specific signal direction it is to be appreciated that such a situation can cover that signal direction and/or its reverse. A main object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), in response to signals received. Another object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by which method blind sectors in the radiation pattern can be avoided. A further object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by which method the radiation pattern can be adapted to optimal reception/transmission. A general object with the invention is to obtain an antenna which can be mounted on a portable communication device, particularly a hand-held radio communication device such as a telephone. These and other objects are attained by a method according to the appended method claims. The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the radiation pattern can be controlled during reception and/or transmission. The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the sensitivity to antenna orientation and transmitter/receiver position can be reduced. The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the performance of the antenna means in stowed position can be improved. The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by which method the average signal and signal-to-noise ratio can be improved. The invention further provides a method for controlling the radiation pattern of an antenna means' comprising N helically configured radiating elements (NHA), by which method the sensitivity to mechanical tolerances in the antenna means can be reduced. » A further main object of the invention is to provide an antenna system comprising N helically configured antenna elements, with which antenna system the radiation pattern can be controlled. Another object of the invention is to provide an antenna system, with which blind sectors in the radiation pattern can be avoided. Another object of the invention is to provide an antenna system, with which the radiation pattern can be adapted to optimal reception/transmission. These and other objects are attained by an antenna system according to the appended system claims. The invention further provides an antenna system, by which the radiation pattern can be controlled during reception and/or transmission. rhe invention further provides an antenna system, in which the sensitivity to antenna orientation and transmitter/receiver position can be reduced. rne invention ruruner proviaes an antenna system, oy which the performance of the antenna system with the radiating elements in stowed position can be improved. The invention further provides an antenna system, by which the average signal and signal-to-noise ratio can be improved. The invention further provides an antenna system, in which the sensitivity to mechanics"! tolerances can "be reduced. A further main object of the invention is to provide a radio communication device having an antenna system with the above mentioned objects. These and other objects are attained by a radio communication device according to the appended claims concerning a radio communication device. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a typical radiation pattern of an N-filar antenna device. Figure 2 shows schematically a quadrifilar antenna device with a typical feeding network according to the prior art. Figure 3 shows a first embodiment of an antenna system according to the invention. Figure 4 shows the radiation pattern of an embodiment of an antenna system according to the invention where the phases are reversed in respect of the phases for "normal feed". Figure 5 shows the radiation pattern of an embodiment of an antenna system according to the invention where the phases. are. reversed in respect of the phases for "normal feed" when the radiating structure is stowed away in an upside down position. Figure 6 shows an antenna system according to a second embodiment of the invention. Figures 7 and 8 show different possibilities how the Tx/Rx chain (s) can be included in an antenna system according to the invention. Figure 9 shows a third embodiment of an antenna system according to the invention. Figure 10 shows a fourth embodiment of an antenna system according to the invention. Figure 11 shows a fifth embodiment of an antenna system according to the invention. Figure 12 shows how the received signals and signals to be transmitted can be separated in two links. Figure 13 shows a "software" example of the embodiment according to figure 9. Figure 14 shows a "hardware" example of the embodiment according to figure 9. Figure 15 shows a directional coupler used in the example of figure 14. Figure 16 shows a phase quadrature hybrid used in the example of figure 14. DESCRIPTION OF PREFERRED EMBODIMENTS It should be noted that similar or corresponding parts have been given the same reference numerals throughout the drawings. With reference to Figure 2, an example of a known antenna system including an antenna device and feed device for transmitting and receiving circularly polarized RF waves in connection to a radio communication device, is diagrammatically shown. It includes a radiating structure 10, which comprises a support 11, which carries four conductive helical radiating elements 12 A-D, which are coextending and coaxially arranged. The so formed quadrifilar radiating structure 10 has a first end 15 and a second end 14. At the first end 15, the helical radiating elements 12 A-D are provided with a respective feed point, or feed portion 13 A-D. A feeding means 20 is connected to the radiating structure 10, for feeding and reception of signals. The feeding means 20 possibly comprises a diplexer 3 0 having an input Tx for signals to be transmitted by the antenna system and comes from the transceiver circuits of the radio communication device, and an output Rx for signals received by the antenna system to be transmitted to the transceiver circuits of the radio communication device. The output 31 of the diplexer 3 0 or the output of the transceiver circuits of the radio communication device is connected to a phasing network 21. The phasing network comprises means for dividing the signals input at input 22 into signals being phase shifted 0°, 90° ,180° and 2 70°, respectively. Each of the outputs of the phasing network 21 is connected, possibly via matching means 23 A-D, with a respective feed portion 13 A~D, so as to obtain a progressive phase shift on the feed portions 13 A-D. A signal put on the Tx input of the diplexer and so divided into phase shifted signals and fed to the radiating structure 10 will create a circularly polarized RF wave to be radiated by the radiating structure 10. Since the radiating structure 10 and the feeding means 20 are passive, they will operate reverse when receiving a circularly polarized RF wave polarized in the same direction. The so described antenna device and feed device can be used for radio communication in systems using satellites, and also for receiving signals in positioning systems using satellites, e.g. GPS. Since the phasing network 21 gives a fixed phase shift between its outputs, the radiation pattern of the radiating structure 10 will be fixed, as shown in figure 1, and can only be adjusted by changing the orientation of the radiating structure 10, e.g. when the radiating structure 10 is attached with a pivoting joint. Figure 3 shows a first embodiment of an antenna system 1 according to the invention comprising N radiating elements 12i-12N, where N is an integer greater than 1. The radiating elements 121-12N are preferably helically configured, similarly to what is shown in figure 2. By helically configured, in this application, is meant a generally helical configuration, with a radiating structure 10, as shown in figure 2, which can have a circular or other than a circular cross section, e.g. of an oval or a polygon and including cross sections being constant as well as cross sections not being constant along a longitudinal axis of the radiating structure 10 (e.g. conical NHA) . Each radiating element 121-12M is connected at its feed portion 131-13N to one of N ports 411-41N of a feed device 40. Each of ports 411-41N is constituted of a first port of an adaptive feed means 421-42N. The other port of each adaptive feed means 422-42N is connected to a power combiner/divider 43, which is connected to the antenna port 44. The antenna port 44 is to be connected to transceiver circuits of a radio communication device. Each adaptive feed means 421-42N transforms (i.e. multiplies) a signal incoming on one of its ports by a function Aneiv" to a signal output on the other port, i.e. both signals received by any one of the radiating elements and signals to be transmitted by the same radiating element are transformed bv the same function. An is an attenuation or amplification favuor (hereafter called the amplitude) and on is a phase shift for the respective adaptive feed means. By adjusting at least one of An and (pn, the radiation pattern of the radiating elements 121-12N can be controlled or adjusted. If for example the phases are reversed in respect of the phases for "normal feed" (when the radiating elements 121-12N are fed with progressive phase shift adapted to the rotational directions of the lelical radiating elements 121-12N) the radiation pattern is changed so that the main lobe M moved to be directed in the opposite direction, as shown in figure 4. This can be very idvantageous if the radiating elements 121-12N are supported by radiating structure 10, which is attached to a telephone body by a pivot joints When the radiating structure 10 is stowed away in standby position the radiation pattern can be :ontrolled for maximal reception/transmission, as illustrated n figure 5. The change of the phase can be mechanically ctuated when the radiating structure 10 is brought to its towed position, or the chance of the phase can take place ontinuously. n figure 6 an antenna system according to a second embodiment f the invention and similar to that shown in figure 3 is shown. In this embodiment the feed device 40 also includes a fixed feed network 45, having N element ports 411-41N connected to the N radiating elements 121-12N. The feed device 40 further includes M adaptive feed means 421-42M connected to M feed ports 461-46M of the fixed feed network 45, where M is an integer greater than 1, which could be equal to N. When M=N the fixed feed network 45 can comprise N conductors connecting sach of the feed ports 461-46M with a corresponding element port 41i-41N. The fixed feed network 45 can be formed so that the phase and /or amplitude on the element ports 411-41N tor controlling the radiation pattern of the radiating elements 421-12N, can be varied by varying the phase and /or amplitude on the feed ports 461-46N by means of the adaptive feed means 421-42N. The fixed feed network 45 can for example be formed so chat the phase and /or amplitude on the element ports 411-41N will cause that the radiation pattern of the radiating elements 121-12N can be switched between different pre-selected radiation patterns by applying signals on one of the feed ports 461-46M only, and changing port on which signals are nput. In this case Am is set to zero for all of the adaptive eed means 421-42M but one. The operation in transmission is he opposite as the described receiving operation. igures 7 and 8 show different possibilities how the Tx/Rx hain(s) 56, 561-56N can be included in an antenna system ccording to the invention. As illustrated, the received ignals and/or signals to be transmitted can be processed in he Tx/Rx chain (s) after or before being combined or divided, espectively. It is also possible that the Tx/Rx chain(s) is are) divided so that components thereof are distributed at he locations shown and also intermediate positions. In figure 9 a third embodiment of the invention is shown. The signals received by the radiating elements 121-12N are sensed in each line between the radiating elements 12i-12N and its associated adaptive feed means 421-42N, by means of sensors or couplers- 481-48N, and measured in a sense and control circuit/algorithm means 47, also called control means 4 7 in this disclosure. In this control means 47, the signal strength and/or phase of each signal received by the radiating elements 12i-12N is measured, and the amplitude An and/or the phase cpn for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 42i-42N/ in order to obtain a desired radiation pattern, preferably for Dptimal reception/transmission. The value of the measured signal strength and/or phase of each signal received by the radiating elements 121-12N can for example be compared with a reference value stored in the control means 47. The reference values can represent signal strengths and/or phases for received signals in the respective radiating elements 121-12N :or different orientations of the transmitter (e.g. a satellite) of the received signals in relation to the •adiating elements. The reference values can represent signal itrengths and/or phases.for received signals in the respective •adiating elements 121-12N from earlier measurements which are tored in the sense and control circuit/algorithm means 47, referably stored with the corresponding values of the arameters phase on and amplitude An. Alternatively, the values f the signal strengths and/or phases for the received signals n the respective radiating elements 121-12N can be compared to ach other and the amplitude An and/or the phase on for the eceived signals and/or signals to be transmitted is (are) ontrolled in the respective adaptive feed means 421-42N ccording to these comparisons in order to obtain a desired radiation pattern, preferably for optimal reception/transmission. The measurements and the control are preferably repeated after certain periods of time or performed continuously. Figure 10 shows a fourth embodiment of the invention similar to that of figure 9. Here, the signals received by the radiating elements 12I-12N are sensed, by means cf sensors or couplers 48i-48N, in each line between the respective adaptive feed means 42!-42N and the power combiner/divider 43. This means that the signals that are sensed have been transformed by the adaptive feed means 42i-42N. The sensed signals are measured in a sense and control circuit/algorithm means 47. In this control means 47 the signal strength and/or phase of each signal received by the radiating elements 12!-12;: is measured, and the amplitude An and/or the phase (pn for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 42i-42N, in order to obtain a desired radiation pattern, preferably for optimal reception/transmission. The values of the measured signals are preferably compared with reference values for the control. The reference values can represent signal strengths and/or phases for received signals in the respective radiating elements 12X-12N from earlier measurements which are stored in the sense and control circuit/algorithm means 47, preferably stored with the corresponding values of the parameters phase . parameters phase cpn and amplitude An for the adaptive feed means 421-42N, preferably all N at the same time, are measured. The value of the measured signal strength and/or phase of each sensed signal can for example be compared to a reference value stored in the control means 47, and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 421-42N, in order to obtain a desired radiation pattern for optimal reception/transmission. Preferably a signal, or set of N signals, sensed and measured after a change of a parameter phases on and/or amplitude An is compared to the previous value and the parameter (s) is (are) then set to the value of the parameter giving the optimal value of the sensed and measured signal, or set of N signals, for a period of time, after which the change of parameter (s) and measurement (s) continues. Alternatively, the values of the signal strengths arid/or phases for the received signals in the respective radiating elements 121-12N can be compared to each other and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is (are) controlled in the respective adaptive feed means 421-42N according to these comparisons in order to obtain a desired radiation pattern, preferably for optimal reception/transmission. The measurements and the control are preferably repeated after certain periods of time or performed continuously. In figure 11 a fifth embodiment of the invention, similar to that of figure 10, is shown. In this embodiment the received signals are sensed and measured after combination. Here, it is preferred that at least one of the parameters phase on and amplitude An for the adaptive feed means 421-42N is changed, e.g. one parameter at a time for one adaptive feed means 421- 42N at a time in steps or continuously at predetermined or randomly selected times, and the signal strength of the sensed signals with the different values of the parameters phase on and amplitude An for the adaptive feed means 421-42N are measured. The value of the measured signal strength of a sensed signal can for example be compared to a reference value stored in the control means 47, and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 421-42N, in order to obtain a desired radiation pattern for optimal reception/transmission. Preferably a signal sensed and measured after a change of a parameter phase on and/or amplitude An is compared to the previous value and the parameter is then set to the value of the parameter giving the optimal value of the sensed and measured signal for a period of time, after which the change of parameter (s) and measurement (s) continues. The measurement (s) and the control are preferably repeated after certain periods of time or performed continuously. Figure 12 shows how the received signals and signals to be transmitted can be separated in two links by means of duplex Eilters 551-55N, connected to the radiating elements 121-l2N. In one link, the antenna port 44i is connected to the "input" port of the power combiner/divider 431, and the N "output" ports :hereof are connected to their respective N duplex filters 551-55N, via fixed phase shifters 531-53N. In the other link, the mtenna port 442 is connected to the "input" port of the power :ombiner/divider 432, and the N "output" ports thereof are connected to their respective N duplex filters 551-55N, via idaptive feed weans 421-42N. Here, any of the two links can be lsed for received signals, while the other is used for signals to be transmitted. The received signals can be measured and the adaptive feed means 42i-42N can be controlled in any of the ways described in the other embodiments or examples. Figure 13 shows a "software" example of the embodiment according to figure 9. This is an example of selection combining between two axial lobes. Here N=4, and a portion of each of the signals received in the radiating elements 12:-124 is tapped-off and input to the sense and control circuit/algorithm means 47, where each signal is measured and processed according to an algorithm for the control. Signals output from the sense and control circuit/algorithm means 47 are input on each of the adaptive feed means 54i-544, for controlling the phase shift (pn. The adaptive feed means 54:-544 are in this case constituted of variable phase shifters, which varies the phase in steps or continuously. For the understanding of the operation of this embodiment we define two vectors, which represent two lobes 6, , b2 , one directed upwards and one directed downwards (the opposite direction) as: \ ; ■ : i ' r f" i 6, = w, + ju2 -ii3- ju4 j b2 = u, - ju2 - u3 + ju4 \ , where the signals from the four radiating elements 12i-124 forms a four-dimensional vector, where uk is the unit vector corresponding to radiating element 12. The received signals on the radiating elements 12i-124 are read by the sense and control circuit/algorithm means 47 by means of sensors 48i-484, and formed into a vector v according to : V = V,M, + V,W, + V3Z/3 + V4M4 where vk is the complex signal value of a signal received in radiating element 12. Two signals s}, s2 are then calculated, representing the signal strength in the two lobes bx , £>, , respectively: v-b, s-, =\v-bJ The levels of the two signals $,, s2 are compared in the sense and control circuit/algorithm means 47, which decides which phase shift should be loaded to the variable phase shifters 54i-544 so that if st>s2 , the phase shifts will be loaded to the respective variable phase shifter 54i-544, and will be loaded to the if s2>sx, the phase shifts ^,=0° respective variable phase shifter 54i-544. The measurement and the control process is preferably repeated after certain periods of time or performed continuously. In this embodiment both received signals and signals to be transmitted will be phase shifted in the phase shifters 54i-544 before and after entering and exiting the power combiner/divider 43, respectively. The antenna port 44, which is connected to the power combiner/divider 43 is also connected to the transceiver circuits of the radio communication device. Alternatively the sensors 481-48N the sense and control circuit/algorithm means 47, and the phase shifters 541-544 can be included in the telephone circuitry, and then the feed portions 131-134 are connected with the telephone circuitry, preferably to connections on the PCB (printed circuit board) of the telephone circuitry. Figure 14 shows a "hardware" example of the embodiment according to figure 9. This is also an example of select-combining with two axial lobes. Also here N=4, and a portion of each of the signals received in the radiating elements 12i-124 is tapped-off and input to the sense and control circuit/algorithm means 47, where the signals are measured and processed to provide output signals, which are input on each of the adaptive feed means 542, 544# for controlling the phase shift cpn. In this case, only two adaptive feed means 542, 544 are present, and they are constituted of variable phase shifters, which varies the phase shift with the steps 0° and 180°. Also fixed phase shifters 53i-534 are arranged between the sensors and the power combiner/divider for phase shifting the signals to/from the radiating elements 12i-12N 0°, 90°, 180°, 270°, respectively. The sensors 48i-484 are here constituted of directional couplers 48i-484 tapping off a portion of the received signals to be input on the inputs of the sense and control circuit/algorithm means 47. This control means 47 comprises a phase quadrature hybrid 49, having one input port for each directional coupler 48j.-484. Each of the two outputs of the phase quadrature hybrid 4 9 is connected to amplifiers 50A, 50B for amplification of the signals. Each of the two amplified signals is then fed to a comparator 52 via integrators 50A, 50B. Depending on which of the two signals input to the comparator is the highest, the output will be a logical 0 or a logical 1. The output of the comparator is connected to the two phase shifters 422, 424 and depending on if a logical 0 or a logical 1 is input to the phase shifters 422, 424/ the phase shift will be set to 0° or 180°. In the embodiments above, the Tx/Rx chains can be included in the respective antenna system, as described in connection with figures 7 and 8. Figure 15 shows a directional coupler 48 of the kind used in the previous embodiment, of figure 14, with its port designation. The scattering matrix, which shows the transformation of complex input signals to complex output signals is shown in the following formula: where the transformation of a signal input on port c (column c) and output on port 1 (line 1) is given by the matrix. In the formula, x denotes an arbitrary phase. In the matrix, p denotes the coupled portion. If p is selected to 0.1, 10% of the signal power (-10 dB) is tapped off for the control. Figure 16 shows a phase quadrature hybrid 4 9 of the kind used in the previous embodiment, of figure 14, with its port designation. The scattering matrix, which shows the transformation of complex input signals to complex output signals is shown in the following formula: where the transformation of a signal input on port c (column c) and output on port 1 (line 1) is given by the matrix. In the matrix, x represent a non-defined value, which is of none interest in this application. In the respective embodiments above, the property signal strength and/or phase of received signals can be measured. The phase can be measured at different times for received signals in the same radiating element 12J-12N, and the obtained values can be compared. Alternatively the phase can be measured for received signals in at least two of the radiating elements 12i-12N, and the obtained values can be compared. For all embodiments above, but one, the phase The received signal, which is measured is preferably a signal used in the communication, but could also be a special control signal, preferably possible to identify as a control signal, e.g. through its frequency or information content. The antenna system according to the invention is preferably arranged to be used and mounted on a portable, e.g. hand-held terminal, which preferably is capable of communication with a satellite, e.g. a satellite in a system as Iridium, Global Star, ICO, GPS, etc. For such mountings the radiating elements 12i-12N have to be relatively small. Preferably the radiating elements 12i-12N are arranged as shown in figure 2, having a common longitudinal axis. However, the radiating elements 12i-12N can be arranged in other configurations, e.g. if N/2 is an integer, the radiating elements 12i-12N can be arranged in pairs, each radiating element of a pair being arranged opposite each other (180° physical separation in respect to a longitudinal axis) , and each pair can have separate longitudinal axes. The radiating elements of such a pair are preferably fed with a relative phase shift of 180°. Although the invention is described by means of the above examples, naturally, many variations are possible within the scope of the invention. WE CLAIM: A method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater than 1, and being adapted for receiving or receiving and transmitting RF signals, said method comprising the steps of: measuring at least one property of at least one received signal from at least one of said radiating elements, and controlling at least one of the parameters phase (Qn) and amplitude (An) for received signals and/or signals to be transmitted for at least one of the radiating elements as a response to the measured property of said received signal. a response to the measured property of said received signal. 2. The method as claimed in claim 1, wherein the step of measuring at least one property of at least one received signal comprises measuring at least one of the properties signal strength and phase of least one received signal. 3. The method as claimed in claim 2, wherein the signal strength of received signals is measured for at least two radiating elements. 4. The method as claimed in claim 2, wherein the phase of received signals is measured for at least two radiating elements. 5. The method as claimed in claim 1, wherein said at least one parameter for received signals/signals to be transmitted is controlled for each antenna element as a response to the measured property of said received signal. 6. The method as claimed in claim 1, further comprising the step of: varying said at least one parameter between a number of predetermined values of said at least one parameter, wherein signals received in the antenna elements are measured for different values of said at least one parameter, and said at least one parameter for received signals/signals to be transmitted is set, in response to said measured signal property, for at least a predetermined period of time. 7. The method as claimed in claim 6, wherein said step of varying said at least one parameter has varying said at least one parameter at least once from a first to a second values. 8. The method as claimed in claim 6, wherein said at least one parameter is varied one at a time for each antenna element. 9. The method as claimed in claim 1, wherein said at least one property of said at least one received signal is measured separately for each antenna element. 10. The method as claimed in claim 1, having the step of combining signals received in said radiating elements, wherein said step of measuring at least one property is performed on the combined signal. 11. The method as claimed in claim 1, wherein said at least one parameter is controlled according to an algorithm implemented in transceiver circuits of a radio communication device. 12. The method as claimed in claim 1, wherein said at least one parameter is varied between values for obtaining at least two differently directed radiation lobes, the signal strengths of signals received by the radiating elements in said at least two differently directed radiation lobes are measured, and said at least one parameter is set to the value giving the highest signal strength for at least a predetermined period of time. 13. The method as claimed in claim 12, wherein two of the at least two differently directed radiation lobes are directed essentially oppositely. 14. The method as claimed in claim 1, wherein said steps of measuring and controlling are repeated after a predetermined or randomly selected time period. 15. An antenna system, for receiving or receiving and transmitting RF signals, comprising N helically configured radiating elements, where N is an integer greater than 1, a feed device, where each of said radiating elements exhibits a feed portion connected to the feed device, the feed device includes means for controlling at least one of the parameters phase (Qn) and amplitude (An) for signals received and/or signals to be transmitted by at least one of the antenna elements, and means for sensing and measuring at least one property of a signal received in at least one of said radiating elements, said means for sensing and measuring being connected to said means for controlling at least one of said parameters. 16. The antenna system as claimed in claim 15, wherein said means for sensing being arranged to sense a signal present between said at least one radiating element and its connection to said feed means. 17. The antenna system as claimed in claim 15, further comprising: a power combiner/ divider being connected with the N radiating elements, possibly via means for controlling said at least parameter, and to be connected to transceiver circuits of a radio communication device wherein said means for sensing being arranged to sense a signal present between said power combiner/divider and said means for controlling at least one of said parameters. 18. The antenna system as claimed in claim 15, further comprising: a power combiner/divider being connected with the N radiating elements, possibly via means for controlling said at least parameter, and to be connected to transceiver circuits of a radio communication device wherein said means for sensing is arranged to sense a signal present between said power combiner/divider and said transceiver circuits. 19. The antenna system as claimed in claim 15, wherein the feed device has a fixed feed network, having N element ports, each connected to one of the N radiating elements, and the feed device further has M means, for controlling said at least one parameter, each of said M means connected to one of M feed ports of the fixed feed network, where M is an integer greater than 1. 20. The antenna system as claimed in claim 15, wherein said means for controlling said at least one parameter has an algorithm. 21. The antenna system as claimed in claim 20, wherein said algorithm is included in a digital signal processor of a radio communication device. 22. A radio communication device comprising a housing, a user interface, and receiving or receiving and transmitting circuits connected to an antenna system, the device has an antenna system comprising; N helically configured radiating elements, where N is an integer greater than 1, a feed device, where each of said radiating elements exhibits a feed portion connected to the feed device, the feed device having means for controlling at least one of the parameters phase (Qn) and amplitude (An) for signals received and/or signals to be transmitted by at least one of the antenna elements, and means for sensing and measuring at least one property of a signal received in at least one of said radiating elements, said means for sensing and measuring being connected to said means for controlling at least one of said parameters. 23. The radio communication device as claimed in claim 22, wherein the N radiating elements are arranged on a carrier being pivotably attached to the housing. 24. The radio communication device as claimed in claim 22, wherein N radiating element are arranged on a carrier being slidably attached to the housing. 25. The radio communication device as claimed in claim 22, wherein said means for controlling said at least one parameter is supported by said carrier. Dated this 15th day of November, 2001. [RITUSHKA NEGI] OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Full Text

FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
COMPLETE SPECIFICATION
[See Section 10]
"A METHOD FOR CONTROLLING THE RADIATION PATTERN OF AN ANTENNA MEANS, AN ANTENNA SYSTEM AND A RADIO COMMUNICATION DEVICE"
ALLGON AB, a Swedish Body Company, of Antennvagen 6, S-187 80 Taby, Sweden
The following specification particularly describes and ascertain the nature of the invention and the manner in which it is to be performed :-

FIELD OF THE INVENTION
The invention relates to a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater
signals. It also relates to an antenna system for transmission/reception of RF. signals, comprising N helically configured antenna elements, where N is an integer greater than 1, and being adapted for transmitting and/or receiving RF signals. The invention further relates to a radio communication device incluing such an antenna system.
BACKGROUND OF THE INVENTION AND RELATED ART
For antenna applications where a hemispherical coverage with circular polarization is desired, a quadrifilar helix antenna (QHA) can be used. An advantage of the QHA is the ability to shape the radiation pattern from a narrow axial beam to a very broad beam covering almost the entire sphere. The pattern can also be designed to have peaks and dips at certain angles. This is done by exciting different radiation modes, axial and/or radial ones.
A QHA consists of four wires wound around a cylindrical or conical surface with a constant pitch angle. Usually, when space is limited, the choice is a narrow and short cylindrical QHA, having three degreed of freedom (e.g. diameter, pitch angle, length) . Allowing the surface to be conical gives one extra decree of freedom, and can significantly increase the bandwidth.

Modifications can be added to the helices to achieve certain features. Each helix can for example be split in two, the halves having different lengths, for double tuning. Also, if the circumference is large enough, the helices can be meandered to reduce the length of the antenna. A QHA is fed at either the bottom or the top end by means of a feed network.
Several guadrifilar helix antennas (QHA), are known from patents and published patent applications. A large number of these disclose quadrifilar antenna structures for circularly-polarized radio signals. See, for example, WO 98/28815, WO 97/06579, WO 97/11507, US 5,191,352, US 5,255,005, and US 5,541,617.
In all those antenna structures, helical elements are fed with constant amplitude and constant phase-shift between the helical elements. Figure 1 shows a typical radiation pattern of such an antenna structure mounted to a portable radio¬telephone. The radiation pattern exhibits a main lobe M directed upwards and, in most cases, a minor back lobe B directed downwards when fed with a progressive phase-shift adapted to the rotational directions of the helical elements. Between the lobes, the radiation pattern has a blind sector or null BS, where reception/transmission cannot be performed.
In order to direct the main antenna lobe towards a transmitter/receiver (e.g. a satellite) with which a radio communication device is to communicate, telephones having an antenna structure mounted to the telephone housing with a pivot joint have for example been provided. The orientation of the antenna structure can then be adjusted manually for good signal transmission/reception. New adjustments can take place when the transmitter/receiver has changed location or when the telephone has been moved. An example of an antenna structure

mounted with a pivoting joint to a telephone is disclosed in US-A-5,628,057.
In EP 0881782 a mobile station, in a mobile communication system, having a plurality of antenna elements is described. A signal received by an antenna element is demodulated and the phase and power of the signal is detected. On the basis of the results a control device calculates the phase and the power of a transmission signal, which is transmitted to each antenna element. The distance between each antenna element is greater than X/2, which makes the antenna arrangement rather large, not suitable for handheld communication applications. Each antenna element is provided with a receiver and transmitter which are space consuming and thus also makes it not suitable for handheld communication applications.
SUMMARY OF THE INVENTION
In this disclosure it is to be understood that the antenna system of the invention is operable to receive or receive and transmit radio signals. Even if a term is used herein that suggests one specific signal direction it is to be appreciated that such a situation can cover that signal direction and/or its reverse.
A main object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), in response to signals received.
Another object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by

which method blind sectors in the radiation pattern can be avoided.
A further object of the invention is to provide a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by which method the radiation pattern can be adapted to optimal reception/transmission.
A general object with the invention is to obtain an antenna which can be mounted on a portable communication device, particularly a hand-held radio communication device such as a telephone.
These and other objects are attained by a method according to the appended method claims.
The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the radiation pattern can be controlled during reception and/or transmission.
The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the sensitivity to antenna orientation and transmitter/receiver position can be reduced.
The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA) , by which method the performance of the antenna means in stowed position can be improved.

The invention further provides a method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements (NHA), by which method the average signal and signal-to-noise ratio can be improved.
The invention further provides a method for controlling the radiation pattern of an antenna means' comprising N helically configured radiating elements (NHA), by which method the sensitivity to mechanical tolerances in the antenna means can
be reduced.
» A further main object of the invention is to provide an
antenna system comprising N helically configured antenna
elements, with which antenna system the radiation pattern can
be controlled.
Another object of the invention is to provide an antenna system, with which blind sectors in the radiation pattern can be avoided.
Another object of the invention is to provide an antenna system, with which the radiation pattern can be adapted to optimal reception/transmission.
These and other objects are attained by an antenna system according to the appended system claims.
The invention further provides an antenna system, by which the radiation pattern can be controlled during reception and/or transmission.
rhe invention further provides an antenna system, in which the sensitivity to antenna orientation and transmitter/receiver position can be reduced.

rne invention ruruner proviaes an antenna system, oy which the performance of the antenna system with the radiating elements in stowed position can be improved.
The invention further provides an antenna system, by which the average signal and signal-to-noise ratio can be improved.
The invention further provides an antenna system, in which the sensitivity to mechanics"! tolerances can "be reduced.
A further main object of the invention is to provide a radio communication device having an antenna system with the above mentioned objects.
These and other objects are attained by a radio communication device according to the appended claims concerning a radio communication device.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a typical radiation pattern of an N-filar antenna device.
Figure 2 shows schematically a quadrifilar antenna device with a typical feeding network according to the prior art.
Figure 3 shows a first embodiment of an antenna system according to the invention.
Figure 4 shows the radiation pattern of an embodiment of an antenna system according to the invention where the phases are reversed in respect of the phases for "normal feed".
Figure 5 shows the radiation pattern of an embodiment of an antenna system according to the invention where the phases. are. reversed in respect of the phases for "normal feed" when the radiating structure is stowed away in an upside down position.

Figure 6 shows an antenna system according to a second embodiment of the invention.
Figures 7 and 8 show different possibilities how the Tx/Rx chain (s) can be included in an antenna system according to the invention.
Figure 9 shows a third embodiment of an antenna system according to the invention.
Figure 10 shows a fourth embodiment of an antenna system according to the invention.
Figure 11 shows a fifth embodiment of an antenna system according to the invention.
Figure 12 shows how the received signals and signals to be transmitted can be separated in two links.
Figure 13 shows a "software" example of the embodiment according to figure 9.
Figure 14 shows a "hardware" example of the embodiment according to figure 9.
Figure 15 shows a directional coupler used in the example of figure 14.
Figure 16 shows a phase quadrature hybrid used in the example of figure 14.
DESCRIPTION OF PREFERRED EMBODIMENTS
It should be noted that similar or corresponding parts have been given the same reference numerals throughout the drawings.

With reference to Figure 2, an example of a known antenna system including an antenna device and feed device for transmitting and receiving circularly polarized RF waves in connection to a radio communication device, is diagrammatically shown. It includes a radiating structure 10, which comprises a support 11, which carries four conductive helical radiating elements 12 A-D, which are coextending and coaxially arranged.
The so formed quadrifilar radiating structure 10 has a first end 15 and a second end 14. At the first end 15, the helical radiating elements 12 A-D are provided with a respective feed point, or feed portion 13 A-D.
A feeding means 20 is connected to the radiating structure 10, for feeding and reception of signals. The feeding means 20 possibly comprises a diplexer 3 0 having an input Tx for signals to be transmitted by the antenna system and comes from the transceiver circuits of the radio communication device, and an output Rx for signals received by the antenna system to be transmitted to the transceiver circuits of the radio communication device. The output 31 of the diplexer 3 0 or the output of the transceiver circuits of the radio communication device is connected to a phasing network 21. The phasing network comprises means for dividing the signals input at input 22 into signals being phase shifted 0°, 90° ,180° and
2 70°, respectively. Each of the outputs of the phasing network 21 is connected, possibly via matching means 23 A-D, with a respective feed portion 13 A~D, so as to obtain a progressive phase shift on the feed portions 13 A-D. A signal put on the Tx input of the diplexer and so divided into phase shifted signals and fed to the radiating structure 10 will create a

circularly polarized RF wave to be radiated by the radiating structure 10.
Since the radiating structure 10 and the feeding means 20 are passive, they will operate reverse when receiving a circularly polarized RF wave polarized in the same direction.
The so described antenna device and feed device can be used for radio communication in systems using satellites, and also for receiving signals in positioning systems using satellites, e.g. GPS.
Since the phasing network 21 gives a fixed phase shift between its outputs, the radiation pattern of the radiating structure 10 will be fixed, as shown in figure 1, and can only be adjusted by changing the orientation of the radiating structure 10, e.g. when the radiating structure 10 is attached with a pivoting joint.
Figure 3 shows a first embodiment of an antenna system 1 according to the invention comprising N radiating elements 12i-12N, where N is an integer greater than 1. The radiating elements 121-12N are preferably helically configured, similarly to what is shown in figure 2. By helically configured, in this application, is meant a generally helical configuration, with a radiating structure 10, as shown in figure 2, which can have a circular or other than a circular cross section, e.g. of an oval or a polygon and including cross sections being constant as well as cross sections not being constant along a longitudinal axis of the radiating structure 10 (e.g. conical NHA) . Each radiating element 121-12M is connected at its feed portion 131-13N to one of N ports 411-41N of a feed device 40. Each of ports 411-41N is constituted of a first port of an adaptive feed means 421-42N. The other port of each adaptive

feed means 422-42N is connected to a power combiner/divider 43, which is connected to the antenna port 44. The antenna port 44 is to be connected to transceiver circuits of a radio communication device.
Each adaptive feed means 421-42N transforms (i.e. multiplies) a signal incoming on one of its ports by a function Aneiv" to a signal output on the other port, i.e. both signals received by any one of the radiating elements and signals to be transmitted by the same radiating element are transformed bv the same function. An is an attenuation or amplification favuor
(hereafter called the amplitude) and on is a phase shift for the respective adaptive feed means. By adjusting at least one of An and (pn, the radiation pattern of the radiating elements 121-12N can be controlled or adjusted. If for example the phases are reversed in respect of the phases for "normal feed" (when the radiating elements 121-12N are fed with progressive phase shift adapted to the rotational directions of the lelical radiating elements 121-12N) the radiation pattern is changed so that the main lobe M moved to be directed in the opposite direction, as shown in figure 4. This can be very idvantageous if the radiating elements 121-12N are supported by radiating structure 10, which is attached to a telephone body by a pivot joints When the radiating structure 10 is stowed away in standby position the radiation pattern can be :ontrolled for maximal reception/transmission, as illustrated n figure 5. The change of the phase can be mechanically ctuated when the radiating structure 10 is brought to its towed position, or the chance of the phase can take place ontinuously.
n figure 6 an antenna system according to a second embodiment f the invention and similar to that shown in figure 3 is

shown. In this embodiment the feed device 40 also includes a fixed feed network 45, having N element ports 411-41N connected to the N radiating elements 121-12N. The feed device 40 further includes M adaptive feed means 421-42M connected to M feed ports 461-46M of the fixed feed network 45, where M is an integer greater than 1, which could be equal to N. When M=N the fixed feed network 45 can comprise N conductors connecting sach of the feed ports 461-46M with a corresponding element port 41i-41N. The fixed feed network 45 can be formed so that the phase and /or amplitude on the element ports 411-41N tor controlling the radiation pattern of the radiating elements 421-12N, can be varied by varying the phase and /or amplitude on the feed ports 461-46N by means of the adaptive feed means 421-42N. The fixed feed network 45 can for example be formed so chat the phase and /or amplitude on the element ports 411-41N will cause that the radiation pattern of the radiating elements 121-12N can be switched between different pre-selected radiation patterns by applying signals on one of the feed ports 461-46M only, and changing port on which signals are nput. In this case Am is set to zero for all of the adaptive eed means 421-42M but one. The operation in transmission is he opposite as the described receiving operation.
igures 7 and 8 show different possibilities how the Tx/Rx hain(s) 56, 561-56N can be included in an antenna system ccording to the invention. As illustrated, the received ignals and/or signals to be transmitted can be processed in he Tx/Rx chain (s) after or before being combined or divided, espectively. It is also possible that the Tx/Rx chain(s) is are) divided so that components thereof are distributed at he locations shown and also intermediate positions.

In figure 9 a third embodiment of the invention is shown. The signals received by the radiating elements 121-12N are sensed in each line between the radiating elements 12i-12N and its associated adaptive feed means 421-42N, by means of sensors or couplers- 481-48N, and measured in a sense and control circuit/algorithm means 47, also called control means 4 7 in this disclosure. In this control means 47, the signal strength and/or phase of each signal received by the radiating elements 12i-12N is measured, and the amplitude An and/or the phase cpn for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 42i-42N/ in order to obtain a desired radiation pattern, preferably for Dptimal reception/transmission. The value of the measured signal strength and/or phase of each signal received by the radiating elements 121-12N can for example be compared with a reference value stored in the control means 47. The reference values can represent signal strengths and/or phases for received signals in the respective radiating elements 121-12N :or different orientations of the transmitter (e.g. a satellite) of the received signals in relation to the •adiating elements. The reference values can represent signal itrengths and/or phases.for received signals in the respective •adiating elements 121-12N from earlier measurements which are tored in the sense and control circuit/algorithm means 47, referably stored with the corresponding values of the arameters phase on and amplitude An. Alternatively, the values f the signal strengths and/or phases for the received signals n the respective radiating elements 121-12N can be compared to ach other and the amplitude An and/or the phase on for the eceived signals and/or signals to be transmitted is (are) ontrolled in the respective adaptive feed means 421-42N ccording to these comparisons in order to obtain a desired

radiation pattern, preferably for optimal
reception/transmission. The measurements and the control are preferably repeated after certain periods of time or performed continuously.
Figure 10 shows a fourth embodiment of the invention similar to that of figure 9. Here, the signals received by the radiating elements 12I-12N are sensed, by means cf sensors or couplers 48i-48N, in each line between the respective adaptive feed means 42!-42N and the power combiner/divider 43. This means that the signals that are sensed have been transformed by the adaptive feed means 42i-42N. The sensed signals are measured in a sense and control circuit/algorithm means 47. In this control means 47 the signal strength and/or phase of each signal received by the radiating elements 12!-12;: is measured, and the amplitude An and/or the phase (pn for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 42i-42N, in order to obtain a desired radiation pattern, preferably for optimal reception/transmission. The values of the measured signals are preferably compared with reference values for the control. The reference values can represent signal strengths and/or phases for received signals in the respective radiating elements 12X-12N from earlier measurements which are stored in the sense and control circuit/algorithm means 47, preferably stored with the corresponding values of the parameters phase
. parameters phase cpn and amplitude An for the adaptive feed means 421-42N, preferably all N at the same time, are measured. The value of the measured signal strength and/or phase of each sensed signal can for example be compared to a reference value stored in the control means 47, and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 421-42N, in order to obtain a desired radiation pattern for optimal reception/transmission. Preferably a signal, or set of N signals, sensed and measured after a change of a parameter phases on and/or amplitude An is compared to the previous value and the parameter (s) is (are) then set to the value of the parameter giving the optimal value of the sensed and measured signal, or set of N signals, for a period of time, after which the change of parameter (s) and measurement (s) continues. Alternatively, the values of the signal strengths arid/or phases for the received signals in the respective radiating elements 121-12N can be compared to each other and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is (are) controlled in the respective adaptive feed means 421-42N according to these comparisons in order to obtain a desired radiation pattern, preferably for optimal reception/transmission. The measurements and the control are preferably repeated after certain periods of time or performed continuously.
In figure 11 a fifth embodiment of the invention, similar to that of figure 10, is shown. In this embodiment the received signals are sensed and measured after combination. Here, it is preferred that at least one of the parameters phase on and amplitude An for the adaptive feed means 421-42N is changed, e.g. one parameter at a time for one adaptive feed means 421-

42N at a time in steps or continuously at predetermined or randomly selected times, and the signal strength of the sensed signals with the different values of the parameters phase on and amplitude An for the adaptive feed means 421-42N are measured. The value of the measured signal strength of a sensed signal can for example be compared to a reference value stored in the control means 47, and the amplitude An and/or the phase on for the received signals and/or signals to be transmitted is controlled in the respective adaptive feed means 421-42N, in order to obtain a desired radiation pattern for optimal reception/transmission. Preferably a signal sensed and measured after a change of a parameter phase on and/or amplitude An is compared to the previous value and the parameter is then set to the value of the parameter giving the optimal value of the sensed and measured signal for a period of time, after which the change of parameter (s) and measurement (s) continues. The measurement (s) and the control are preferably repeated after certain periods of time or performed continuously.
Figure 12 shows how the received signals and signals to be transmitted can be separated in two links by means of duplex Eilters 551-55N, connected to the radiating elements 121-l2N. In one link, the antenna port 44i is connected to the "input" port of the power combiner/divider 431, and the N "output" ports :hereof are connected to their respective N duplex filters 551-55N, via fixed phase shifters 531-53N. In the other link, the mtenna port 442 is connected to the "input" port of the power :ombiner/divider 432, and the N "output" ports thereof are connected to their respective N duplex filters 551-55N, via idaptive feed weans 421-42N. Here, any of the two links can be lsed for received signals, while the other is used for signals to be transmitted. The received signals can be measured and

the adaptive feed means 42i-42N can be controlled in any of the ways described in the other embodiments or examples.
Figure 13 shows a "software" example of the embodiment according to figure 9. This is an example of selection combining between two axial lobes. Here N=4, and a portion of each of the signals received in the radiating elements 12:-124 is tapped-off and input to the sense and control circuit/algorithm means 47, where each signal is measured and processed according to an algorithm for the control. Signals output from the sense and control circuit/algorithm means 47 are input on each of the adaptive feed means 54i-544, for controlling the phase shift (pn. The adaptive feed means 54:-544 are in this case constituted of variable phase shifters, which varies the phase in steps or continuously. For the understanding of the operation of this embodiment we define
two vectors, which represent two lobes 6, , b2 , one directed upwards and one directed downwards (the opposite direction)
as: \ ; ■
: i ' r
f" i
6, = w, + ju2 -ii3- ju4 j
b2 = u, - ju2 - u3 + ju4 \ ,
where the signals from the four radiating elements 12i-124 forms a four-dimensional vector, where uk is the unit vector corresponding to radiating element 12*. The received signals on the radiating elements 12i-124 are read by the sense and control circuit/algorithm means 47 by means of sensors 48i-484, and formed into a vector v according to :
V = V,M, + V,W, + V3Z/3 + V4M4

where vk is the complex signal value of a signal received in radiating element 12*. Two signals s}, s2 are then calculated,
representing the signal strength in the two lobes bx , £>, , respectively:
v-b,
s-, =\v-bJ
The levels of the two signals $,, s2 are compared in the sense and control circuit/algorithm means 47, which decides which phase shift should be loaded to the variable phase shifters 54i-544 so that

if st>s2 , the phase shifts
will be loaded to the
respective variable phase shifter 54i-544, and

will be loaded to the
if s2>sx, the phase shifts
^,=0° respective variable phase shifter 54i-544. The measurement and the control process is preferably repeated after certain periods of time or performed continuously. In this embodiment both received signals and signals to be transmitted will be phase shifted in the phase shifters 54i-544 before and after entering and exiting the power combiner/divider 43, respectively. The antenna port 44, which is connected to the power combiner/divider 43 is also connected to the transceiver circuits of the radio communication device. Alternatively the

sensors 481-48N the sense and control circuit/algorithm means 47, and the phase shifters 541-544 can be included in the telephone circuitry, and then the feed portions 131-134 are connected with the telephone circuitry, preferably to connections on the PCB (printed circuit board) of the telephone circuitry.
Figure 14 shows a "hardware" example of the embodiment according to figure 9. This is also an example of select-combining with two axial lobes. Also here N=4, and a portion of each of the signals received in the radiating elements 12i-124 is tapped-off and input to the sense and control circuit/algorithm means 47, where the signals are measured and processed to provide output signals, which are input on each of the adaptive feed means 542, 544# for controlling the phase shift cpn. In this case, only two adaptive feed means 542, 544 are present, and they are constituted of variable phase shifters, which varies the phase shift with the steps 0° and 180°. Also fixed phase shifters 53i-534 are arranged between the sensors and the power combiner/divider for phase shifting the signals to/from the radiating elements 12i-12N 0°, 90°, 180°, 270°, respectively. The sensors 48i-484 are here constituted of directional couplers 48i-484 tapping off a portion of the received signals to be input on the inputs of the sense and control circuit/algorithm means 47. This control means 47 comprises a phase quadrature hybrid 49, having one input port for each directional coupler 48j.-484. Each of the two outputs of the phase quadrature hybrid 4 9 is connected to amplifiers 50A, 50B for amplification of the signals. Each of the two amplified signals is then fed to a comparator 52 via integrators 50A, 50B. Depending on which of the two signals input to the comparator is the highest, the output will be a

logical 0 or a logical 1. The output of the comparator is connected to the two phase shifters 422, 424 and depending on if a logical 0 or a logical 1 is input to the phase shifters 422, 424/ the phase shift will be set to 0° or 180°.
In the embodiments above, the Tx/Rx chains can be included in the respective antenna system, as described in connection with figures 7 and 8.
Figure 15 shows a directional coupler 48 of the kind used in the previous embodiment, of figure 14, with its port designation. The scattering matrix, which shows the transformation of complex input signals to complex output signals is shown in the following formula:

where the transformation of a signal input on port c (column c) and output on port 1 (line 1) is given by the matrix. In the formula, x denotes an arbitrary phase. In the matrix, p denotes the coupled portion. If p is selected to 0.1, 10% of the signal power (-10 dB) is tapped off for the control.
Figure 16 shows a phase quadrature hybrid 4 9 of the kind used in the previous embodiment, of figure 14, with its port designation. The scattering matrix, which shows the transformation of complex input signals to complex output signals is shown in the following formula:

where the transformation of a signal input on port c (column c) and output on port 1 (line 1) is given by the matrix. In the matrix, x represent a non-defined value, which is of none interest in this application.
In the respective embodiments above, the property signal strength and/or phase of received signals can be measured. The phase can be measured at different times for received signals in the same radiating element 12J-12N, and the obtained values can be compared. Alternatively the phase can be measured for received signals in at least two of the radiating elements 12i-12N, and the obtained values can be compared.
For all embodiments above, but one, the phase The received signal, which is measured is preferably a signal used in the communication, but could also be a special control signal, preferably possible to identify as a control signal, e.g. through its frequency or information content.

The antenna system according to the invention is preferably arranged to be used and mounted on a portable, e.g. hand-held terminal, which preferably is capable of communication with a satellite, e.g. a satellite in a system as Iridium, Global Star, ICO, GPS, etc. For such mountings the radiating elements 12i-12N have to be relatively small. Preferably the radiating elements 12i-12N are arranged as shown in figure 2, having a common longitudinal axis. However, the radiating elements 12i-12N can be arranged in other configurations, e.g. if N/2 is an integer, the radiating elements 12i-12N can be arranged in pairs, each radiating element of a pair being arranged opposite each other (180° physical separation in respect to a longitudinal axis) , and each pair can have separate longitudinal axes. The radiating elements of such a pair are preferably fed with a relative phase shift of 180°.
Although the invention is described by means of the above examples, naturally, many variations are possible within the scope of the invention.

WE CLAIM:

A method for controlling the radiation pattern of an antenna means comprising N helically configured radiating elements, where N is an integer greater than 1, and being adapted for receiving or receiving and transmitting RF signals, said method comprising the steps of:
measuring at least one property of at least one received signal from at
least one of said radiating elements, and controlling at least one of the
parameters phase (Qn) and amplitude (An) for received signals and/or
signals to be transmitted for at least one of the radiating elements as

a response to the measured property of said received signal.
a response to the measured property of said received signal.
2. The method as claimed in claim 1, wherein the step of measuring at least one property of at least one received signal comprises measuring at least one of the properties signal strength and phase of least one received signal.
3. The method as claimed in claim 2, wherein the signal strength of received signals is measured for at least two radiating elements.
4. The method as claimed in claim 2, wherein the phase of received signals is measured for at least two radiating elements.

5. The method as claimed in claim 1, wherein said at least one parameter for received signals/signals to be transmitted is controlled for each antenna element as a response to the measured property of said received signal.
6. The method as claimed in claim 1, further comprising the step of: varying said at least one parameter between a number of predetermined values of said at least one parameter, wherein signals received in the antenna elements are measured for different values of said at least one parameter, and
said at least one parameter for received signals/signals to be transmitted is set, in response to said measured signal property, for at least a predetermined period of time.
7. The method as claimed in claim 6, wherein said step of varying said at least one parameter has varying said at least one parameter at least once from a first to a second values.
8. The method as claimed in claim 6, wherein said at least one parameter is varied one at a time for each antenna element.
9. The method as claimed in claim 1, wherein said at least one property of said at least one received signal is measured separately for each antenna element.

10. The method as claimed in claim 1, having the step of combining signals received in said radiating elements, wherein said step of measuring at least one property is performed on the combined signal.
11. The method as claimed in claim 1, wherein said at least one parameter is controlled according to an algorithm implemented in transceiver circuits of a radio communication device.
12. The method as claimed in claim 1, wherein
said at least one parameter is varied between values for obtaining at
least two differently directed radiation lobes,
the signal strengths of signals received by the radiating elements in
said at least two differently directed radiation lobes are measured,
and
said at least one parameter is set to the value giving the highest signal
strength for at least a predetermined period of time.
13. The method as claimed in claim 12, wherein two of the at least two differently directed radiation lobes are directed essentially oppositely.
14. The method as claimed in claim 1, wherein said steps of measuring and controlling are repeated after a predetermined or randomly selected time period.

15. An antenna system, for receiving or receiving and transmitting RF
signals, comprising N helically configured radiating elements, where N
is an integer greater than 1, a feed device, where each of said
radiating elements exhibits a feed portion connected to the feed
device,
the feed device includes means for controlling at least one of the parameters phase (Qn) and amplitude (An) for signals received and/or signals to be transmitted by at least one of the antenna elements, and means for sensing and measuring at least one property of a signal received in at least one of said radiating elements, said means for sensing and measuring being connected to said means for controlling at least one of said parameters.
16. The antenna system as claimed in claim 15, wherein said means for sensing being arranged to sense a signal present between said at least one radiating element and its connection to said feed means.
17. The antenna system as claimed in claim 15, further comprising:
a power combiner/ divider being connected with the N radiating elements, possibly via means for controlling said at least parameter, and to be connected to transceiver circuits of a radio communication device wherein
said means for sensing being arranged to sense a signal present between said power combiner/divider and said means for controlling at least one of said parameters.

18. The antenna system as claimed in claim 15, further comprising:
a power combiner/divider being connected with the N radiating elements, possibly via means for controlling said at least parameter, and to be connected to transceiver circuits of a radio communication device wherein
said means for sensing is arranged to sense a signal present between said power combiner/divider and said transceiver circuits.
19. The antenna system as claimed in claim 15, wherein the feed device
has a fixed feed network, having N element ports, each connected to
one of the N radiating elements, and
the feed device further has M means, for controlling said at least one parameter, each of said M means connected to one of M feed ports of the fixed feed network, where M is an integer greater than 1.
20. The antenna system as claimed in claim 15, wherein said means for controlling said at least one parameter has an algorithm.
21. The antenna system as claimed in claim 20, wherein said algorithm is included in a digital signal processor of a radio communication device.
22. A radio communication device comprising a housing, a user interface, and receiving or receiving and transmitting circuits connected to an antenna system,

the device has an antenna system comprising;
N helically configured radiating elements, where N is an integer
greater than 1,
a feed device, where each of said radiating elements exhibits a feed
portion connected to the feed device, the feed device having means for
controlling at least one of the parameters phase (Qn) and amplitude
(An) for signals received and/or signals to be transmitted by at least
one of the antenna elements,
and means for sensing and measuring at least one property of a signal
received in at least one of said radiating elements, said means for
sensing and measuring being connected to said means for controlling
at least one of said parameters.
23. The radio communication device as claimed in claim 22, wherein the N radiating elements are arranged on a carrier being pivotably attached to the housing.
24. The radio communication device as claimed in claim 22, wherein N radiating element are arranged on a carrier being slidably attached to the housing.

25. The radio communication device as claimed in claim 22, wherein said means for controlling said at least one parameter is supported by said carrier.
Dated this 15th day of November, 2001.
[RITUSHKA NEGI]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS

Documents:

abstract1.jpg

in-pct-2001-01428-mum-cancelled pages(17-05-2005).pdf

in-pct-2001-01428-mum-claims(granted)-(17-05-2005).doc

in-pct-2001-01428-mum-claims(granted)-(17-05-2005).pdf

in-pct-2001-01428-mum-correspondence(17-05-2005).pdf

in-pct-2001-01428-mum-correspondence(ipo)-(19-10-2006).pdf

in-pct-2001-01428-mum-drawing(17-05-2005).pdf

in-pct-2001-01428-mum-form 1(15-11-2001).pdf

in-pct-2001-01428-mum-form 19(07-04-2004).pdf

in-pct-2001-01428-mum-form 2(granted)-(17-05-2005).doc

in-pct-2001-01428-mum-form 2(granted)-(17-05-2005).pdf

in-pct-2001-01428-mum-form 3(15-11-2001).pdf

in-pct-2001-01428-mum-form 3(17-05-2005).pdf

in-pct-2001-01428-mum-form 5(15-11-2001).pdf

in-pct-2001-01428-mum-form 6(05-09-2003).pdf

in-pct-2001-01428-mum-form-pct-ipea-409(15-11-2001).pdf

in-pct-2001-01428-mum-petition under rule 137(17-05-2005).pdf

in-pct-2001-01428-mum-power of authority(17-05-2005).pdf

in-pct-2001-01428-mum-power of authority(18-08-2003).pdf

in-pct-2001-01428-mum-power of authority(21-12-2001).pdf

« Previous Patent

Next Patent »

Patent Number

203028

Indian Patent Application Number

IN/PCT/2001/01428/MUM

PG Journal Number

15/2007

Publication Date

13-Apr-2007

Grant Date

19-Oct-2006

Date of Filing

15-Nov-2001

Name of Patentee

ALLGON AB

Applicant Address

ANTENNVAGEN 6, S-187 80 TABY, SWEDEN.

Inventors:

#	Inventor's Name	Inventor's Address
1	PAUL HALLBJORNER	MILPALEGATAN 3A, S-412 64 GOTEBORG, SWEDEN.

PCT International Classification Number

N/A

PCT International Application Number

PCT/SE00/01213

PCT International Filing date

2000-06-09

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	9902213-9	1999-06-11	Sweden