Title of Invention

DIRECTED DIPOLE ANTENNA

Abstract

A dual polarized variable beam tilt antenna having a superior Sector power Ratio(SPR). The antenna may have slant 45 dipole radiating elements including directors, and may be disposed on a plurality of titled element trays to orient an antenna boresight downtill. The directors may be disposed above or about the respective dipole radiating elements. The antenna has a beam front-to-side ratio exceeding 20 dB, a horizontal beam front-to-back ratio exceeding 40 dB, a high-roll off, and is operable over an expanded frequency range.

Full Text

FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10, rule 13) "DIRECTED DIPOLE ANTENNA ANDREW CORPORATION 10500, W.153rd Street, Orland Park, IL 60462 (United States) The following specification particularly describes the invention and the manner in which it is to be performed. WO 2005/122331 PCT/US2005/0I2528 FIELD OF THE INVENTION The present invention is related to the field of antennas, and more particularly to antennas having dipole radiating elements utilized in wireless 5 communication systems. BACKGROUND OF THE INVENTION Wireless mobile communication networks continue to be deployed and improved upon given the increased 10 traffic demands on the networks, the expanded coverage areas for service and the new systems being deployed. Cellular type communication systems derive their name in that a plurality of antenna systems, each serving a sector or area commonly referred to as a cell, are l5 implemented to effect coverage for a larger service area. The collective cells make up the total service area for a particular wireless communication network. Serving each cell is an antenna array and associated switches connecting the cell into the 20 overall communication network. Typically, the antenna array is divided into sectors, where each antenna serves a respective sector. For instance, three antennas of an antenna system may serve three sectors, each having a range of coverage of about 120°. These 25 antennas are typically vertically polarized and have some degree of downtilt such that the radiation 2 WO 2005/122331 PCT/US2005/0I252X pattern of the antenna is directed slightly downwardly towards the mobile handsets used by the customers. This desired downtilt is often a function of terrain and other geographical features. However, the optimum 5 value of downtilt is not always predictable prior to actual installation and testing. Thus, there is always the need for custom setting of each antenna downtilt upon installation of the actual antenna. Typically, high capacity cellular type systems can 10 require re-optimization during a 24 hour period. In addition, customers want antennas with the highest gain for a given size and with very little intermodulation (IM). Thus, the customer can dictate which antenna is best for a given network 15 implementation. It is a further objective of the invention to provide a dual polarized antenna having improved . directivity and providing improved sector isolation to realize an improved Sector Power Ratio (SPR). 20 It is an objective of the present invention to provide a dual polarized antenna array having optimized horizontal plane radiation patterns. One objective is to provide a radiation pattern having at least a 20 dB horizontal beam front-to-side ratio, at 25 least a 40 dB horizontal beam front-to-back ratio, and improved roll-off. 3 WO 2005/122331 PCT/I.S20O5/OI252N It is another objective of the invention to provide an antenna array with optimized cross polarization performance with a minimum of 10 dB co-pol to cross-pol ratio in a 120 degree horizontal 5 sector. It is another objective of the invention to provide an antenna array with a horizontal pattern beamwidth of 50° to 75°. It is another objective of the invention to 10 provide an antenna array with minimized intermodulation. It is an objective of the invention to provide a dual polarized antenna array capable of operating over an expanded frequency range. It is a further objective of the invention to provide a dual polarized antenna array capable of producing adjustable vertical plane radiation patterns. It is another objective of the invention to provide an antenna with enhanced port to port isolation of at least 30 dB. It is further object of the invention to provide an inexpensive antenna. 4 WO 2005/122331 PCT/US2005/012528 These and other objectives of the invention are provided by an improved antenna array for transmitting and receiving electromagnetic waves with +45°and -45° linear polarizations. 5 5 WO 2005/ 122331 PCT/US2005/012528 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a dual polarized antenna according to a first preferred 5 embodiment of the present invention; Figure 2 is a perspective view of a multi-level groundplane structure with a broadband slant 45 cross dipole radiating element removed therefrom, and a tray cutaway to illustrate a tilting of the groundplanes 10 and an RF absorber in a RF choke; Figure 3 is a perspective view of N cross-shaped directors supported above the dipole radiating element; Figure 4 is a backside view of one element tray 15 illustrating a microstrip phase shifter design employed to feed each pair of the cross dipole radiating elements; Figure 5 is a backside view of the dual polarized antenna illustrating the cable feed network, each 20 microstrip phase shifter feeding one of the other dual polarized antennas; 6 WO 2005/122331 PCT/US2005/012528 Figure 6 is a perspective view of the dual polarized antenna including an RF absorber functioning to dissipate RF radiation from the phase shifter microstriplines, and preventing the RF current cross 5 coupling; Figure 7 is a graph depicting the high roll-off radiation pattern achieved by the present invention, as compared to a typical cross dipole antenna radiation pattern; 10 Figure 8A and 8B are graphs depicting the beam patterns in a three sector site utilizing standard panel antennas; Figure 9A and 9B are graphs depicting the beam patterns in a three sector site utilizing antennas 15 according to the present invention; Figure 10 is a perspective view of another embodiment of the invention including dual-band radiating elements; Figure 11 is a perspective view of the embodiment 20 shown in Figure 10 having director rings disposed over one of the radiating elements; Figure 12 is a perspective view of an embodiment of the invention having director rings disposed over each of the radiating elements; 7 WO 20415/122331 PCT/US2005/0I2528 Figure 13 is a view of various suitable configurations of directors; Figure 14 is a close-up view of a dual-band antenna; and 5 Figure 15 depicts an array of dual-band and single-band dipole radiating elements. 8 WO 2005/122331 PCT/US2005/0I252S DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figure 1, there is generally shown at 10 a wideband dual polarized base station 5 antenna having an optimized horizontal radiation pattern and also having a variable vertical beam tilt. Antenna 10 is seen to include a plurality of element trays 12 having disposed thereon broadband slant 45 cross dipole (x-dipole) radiating elements 14 arranged l0 in dipole pairs 16. Each of the element trays 12 is tilted and arranged in a "fallen domino" arrangement and supported by a pair of tray supports 20. The integrated element trays 12 and tray supports 20 are secured upon and within an external tray 22 such that 15 there is a gap laterally defined between the tray supports 20 and the sidewalls of tray 22, as shown in Figure 1 and Figure 2. Bach tray element 12 has an upper surface defining a groundplane for the respective dipole pair 16, and has a respective air 20 dielectric micro stripline 30 spaced thereabove and feeding each of the dipole radiating elements 14 of dipole pairs 16, as shown. A plurality of electrically conductive arched straps 26 are secured between the sidewalls of tray 22 to provide both 25 rigidity of the antenna 10, and also to improve isolation between dipole radiating elements 14. 9 WO 2005/122331 PCT/US2005/012528 As shown, a pair of cable supports 32 extend above each tray element 12. Supports 32 support a respective low IM RF connection cables 34 from a cable 76 to the air dielectric micro stripline 30 and to 5 microstrip feed network defined on a printed circuit board 50 adhered therebelow, as will be discussed in more detail shortly with reference to Figure 4. Referring now to Figure 2, there is shown a perspective view of the element trays 12 with the 10 sidewall of one tray support 20 and tray 22 partially cut away to reveal the tilted tray elements 12 configured in the "fallen domino" arrangement. Each tray element 12 is arranged in a this "fallen domino" arrangement so as to orient the respective dipole 15 radiating element 14 pattern boresight at a predetermined downtilt, which may, for example, be the midpoint of the array adjustable tilt range. The desired maximum beam squint level of antenna 10 in this example is consistent with about 4° downtilt off 20 of mechanical boresight, instead of about 8° off of mechanical boresight as would be the case without the tilt of the element trays 12. According to the present invention, maximum horizontal beam squint levels have been reduced to about 5° over conventional 25 approaches, which is very acceptable considering the antenna's wide operating bandwidth and tilt range. 10 WO 2005/122331 PCT/US2005/012528 Still referring to Figure 2, there is illustrated that the tray supports 20 are separated from the respective adjacent sidewalls of tray 22 by an elongated gap defining an RF choke 36 therebetween. 5 This choke 36 created by physical geometry advantageously reduces the RF current that flows on the backside of the external tray 22. The reduction of induced currents on the backside of the external tray 22 directly reduces radiation in the rear l0 direction. The critical design criteria of this RF choke 36 involved in maximizing the radiation front -to-back ratio includes the height of the folded up sidewalls 38 of external tray 22, the height of the tray supports 20, and the RF choke 36 between the tray 15 supports 20 and the sidewall lips 38 of tray 22. The RF choke 36 is preferably lambda /4 of the radiating element 14 center frequency* and the RF choke 36 has a narrow bandwidth which is frequency dependent because of internal reflection cancellation in the air 20 dielectric, the choke bandwidth being about 22 percent of the center frequency. According to a further embodiment of the present invention, an RF absorber 39 may be added into the RF choke 36 to make the RF choke less frequency 25 dependent, and thus create a more broadband RF choke. The RF absorber 39 preferably contains a high percentage of carbon that slows and dissipates any RF 11 WO 2005/122331 PCT/US2005/012528 reflection wave from effecting the main beam radiation produced by the cross dipole antenna 12. The slant 4 5 cross dipole antenna 14, as shown, produces a cross polarized main beam radiation at a +/-45 degree 5 orientation, each beam having a horizontal component and a vertical component. The cross polarization is good when these components are uniform and equal in magnitude in 360 degrees. For the panel antenna 10 shown in Figure 1 with the linearly arranged cross 10 dipoles 14, the horizontal component of each beam orientation rolls off faster than the vertical component. This means that the vertical beamwidth is broader than the horizontal beamwidth for each beam orientation, and the vertical components travel along 15 the edge of the respective trays 12 more than the horizontal components. Because the thin metal trays 12 have limited surface area, the surface currents thereon are less likely to reflect the horizontal components back to the main beam radiation. In 20 contrast, along the edges of the respective trays 12 the stair cased baffles 35 have to contain many of the vertical component vector currents. Advantageously, by adding the RF absorber 39 into the RF choke 36, the vertical components of each beam orientation are 25 minimized from reflecting back into the main beam radiation of the cross dipole 14. As such, cross dipoles 14 are not provided with a reflector behind them. 12 WO 2005/122331 PCT/US2005/012528 Preferably, the element trays 12 are fabricated from brass alloy and are treated with a tin plating finish for solderability. The primary function of the element trays is to support the radiating element 14 5 in a specific orientation, as shown. This orientation provides more optimally balanced vertical and horizontal beam patterns for both ports of the antenna 10. This orientation also provides improved isolation between each port. Additionally, the element trays 12 10 provide an RF grounding point at the coaxial cable/airstrip interface. The tray supports are preferably fabricated from aluminum alloy. The primary function of the tray supports is to support the five element trays 12 in a 15 specific orientation that minimizes horizontal pattern beam squint. The external tray 22 is preferably fabricated from a thicker stock, of aluminum alloy than element trays 12, and is preferably treated with an alodine 20 coating to prevent corrosion due to external environment conditions. A primary functions of the external tray 22 is to support the internal array components. A secondary function is to focus the radiated RF power toward the forward sector of the 25 antenna 10 by minimizing radiation toward the back, thereby maximizing the radiation pattern front-to-back ratio, as already discussed. 13 WO 2005/122331 PCT/US2005/012528 Referring now to Figure 3 there is depicted one radiator element 14 having N laterally extending parasitic broadband cross dipole directors 40 disposed above the radiating element 14 and fed by the airstrip 5 feed network 30, as shown. N is 1,2,3,4 , where N is shown to equal 4 in this embodiment. The upper laterally extending members of parasitic broadband cross dipole director 40 are preferably uniformly spaced from one another, with the upper members l0 preferably having a shorter length, as shown for bandwidth broadening. The lower members of director 40 are more closely spaced from the radiating element 14, so as to properly couple the RF energy to the director in a manner that provides pattern enhancement l5 while maintaining an efficient impedance match such that substantially no gain is realized by the director 40, unlike a Yagi-Uda antenna having a reflector and spaced elements each creating gain. Advantageously, rather than realized gain, an improved pattern rolloff 20 is achieved beyond the 3dB beamwidth of the radiation pattern while maintaining a similar 3dB beamwidth. Preferably, the upper elements of directors 40 are spaced about .033 lambda (center frequency) from one another, with the lower director elements spaced from 25 the radiating element 14 about .025 lambda by parasitic 42 (lambda being the wavelength of the center frequency of the radiating element 14 design). 14 WO 2005/122331 PCT/US2005/012528 Referring now to Figure 4 there is shown one low loss printed circuit board (PCB) 50 having disposed thereon a microstrip capacitive phase shifter system generally shown at 52. The low loss PCB 50 is secured 5 to the backside of the respective element tray 12. Microstrip capacitive phase shifter system 52 is coupled to and feeds the opposing respective pair of radiating elements 14 via the respective cables 34. As shown in Figure 4, each microstrip phase 10 shifter system 52 comprises a phase shifter wiper arm 56 having secured thereunder a dielectric member 54 which is arcuately adjustable about a pivot point 58 by a respective shifter rod 60. Shifter rod 60 is longitudinally adjustable by a remote handle (not l5 shown) so as to selectively position the phase shifter wiper arm 56 and the respective dielectric 54 across a pair of arcuate feedline portions 62 and 64 to adjust the phase velocity conducting therethrough. Shifter rod 60 is secured to, but spaced above, PCB 50 by a 20 pair of non-conductive standoffs 66. The low loss coaxial cables 34 are employed as the main transmission media providing electrical connection between the phase shifter system 52 and the radiating elements 14. Gain performance is optimized by closely 25 controlling the phase and amplitude distribution across the radiating elements 14 of antenna 10. The very stable phase shifter design shown in Figure 4 15 WO 2005/122331 PCT/US2005/012528 achieves this control. Referring now to Figure 5, there is shown the backside of the antenna 10 illustrating the cable feed network, each microstrip phase shifter system 52 5 feeding one of the other polarized antennas 14. Input 72 is referred as port I and is the input for the -4 5 polarized Slant, and input 74 is the port II input for the +45 polarized Slant. Cables 76 are the feed lines coupled to one respective phase shifter system 52, as 10 shown in Figure 4. The outputs of phase shifter system 52, depicted as outputs 1-5, indicate the dipole pair 16 that is fed by the respective output of the phase shifter 52 system. Referring now to Figure 6, there is shown antenna l5 10 further including an RF absorber 78 positioned under each of the element trays 12, behind antenna 10, that functions to dissipate any rearward RF radiation from the phase shifter microstrip lines, and preventing RF current from coupling between phase 20 shifters systems 52. Referring now to Figure 7, there is generally shown at 68 the high roll-off and front-to-back ratio radiation pattern achieved by antenna 10 according to the present invention, as compared to a standard 65° 25 panel antenna having a dipole radiation pattern shown at 69. This high roll-off radiation pattern 68 is a 16 WO 2005/122331 PCT/US2005/0I2528 significant improvement over the typical dipole radiation pattern 69. The horizontal beam width still holds at approximately 65 degree at the 3 dB point. 5 Further, the design of the radiating elements 14 with directors 40 provides dramatic improvements in the antenna's horizontal beam radiation pattern, "where the Front-to-Side levels are shown to be 23dB in Figure 7. Conventional, cross dipole radiating l0 elements produce a horizontal beam radiation pattern with about a 17 dB front-to-side ratio, as shown in Figure 7. According to the present invention, the broadband parasitic directors 40 integrated above the radiating elements 14 advantageously improve the l5 antenna front-to-side ratio by up to 10 dB, and is shown as 6dB delta in the example of Figure 7. This improved front-to-side ratio effect is referred to as a "high roll-off design. In this embodiment, radiating elements 14 and cross dipole directors 40 20 advantageously maintain an approximately 65 degree horizontal beamwidth at the antenna's 3 dB point, unlike any conventional Yagi-Uda antenna having more directors to get more gain and thus reducing the horizontal beamwidth. 25 Still referring to Figure 7, there is shown the excellent front-to-back ratio of antenna 10. As shown, panel antenna 10 has a substantially reduced 17 WO 2005/122331 PCT/US2005/0I2528 backside lobe, thus achieving a front-to-back ratio of about 40 dB. Moreover, antenna 10 has a next sector antenna/antenna isolation of about 4 0 dB, as compared to 26 dB for the standard 65° panel antenna. As can 5 also be appreciated in Figure 7, with the significant reduction of a rear lobe, a 12 0° sector interference free zone is provided behind the radiation lobe, referred to in the present invention as the "cone of silence" . 10 Referring now to Figure 8A and 8B, there is shown several advantages of the present invention when employed in a three sector site. Figure 8A depicts standard 65° flat panel antennas used in a three sector site, and Figure 8B depicts standard 90° panel l5 antennas used in a three sector site. The significant overlap of these antenna radiation patterns creates imperfect sectorization that presents opportunities for increased softer hand-offs, interfering signals, dropped calls, and reduced capacity. 20 Referring now to Figure 9A and 9B, there is shown technical advantages of the present invention utilizing a 65° panel antenna and a 90° panel antenna, respectively according to the present invention, employed in a three sector site. With respect to 25 Figure 9A, there is depicted significantly reduced overlap of the antenna radiation lobes, thus realizing a much smaller hand-off area. This leads to dramatic 18 WO 2005/122331 PCT/US2005/0I2528 call quality improvement, and further, a 5-10% site capacity enhancement. Referring back to Figure 7, the undesired lobe extending beyond the 120° sector of radiation creates $ overlap with adjacent antenna radiation patterns, as shown in Figure 8A-8B and Figure 9A-9B. The undesired power delivered in the lobe outside of the 120° forward sector edges, as compared to that desired power delivered inside this 120° sector, defines what l{) is referred to as the Sector Power Ratio (SPR) . Advantageously, the present invention achieves a SPR being less than 2%, where the SPR is defined by the following equation: 300 ^PUndesired SPR (%)=-§ xlOO ^]P Desired 300 lp This SPR is a significant improvement over standard panel antennas, and is one measure of depicting the technical advantages of the present invention. The directors 40 are impedance matched at 90 ohms, although limitation to this impedance is not 2P inferred, to the micro stripline 30. The radiating elements 14 and the cross dipole directors 40 have mutual instantaneous electromagnetic coupling which generate with source impedance at 90 ohm and source voltage of a matching network. Many other system 19 WO 2005/122331 PCT/US2005/0I2528 level performance benefits are afforded by-incorporation of this high roll-off antenna design, including improved soft handoff capabilities, reduced co-site channel interference and increased base 5 station system capacity due to increased sector-to-sector rejection. Referring now to Figure 10, there is shown another preferred embodiment of the invention seen to comprise a band, dualpol antenna 80 including one 10 slant 45 crossed dipole radiating element 14 and a slant 45 microstrip Annular Ring (MAR) radiator 94 encircling said dipole, as will be described shortly in reference to Figure 11. In this embodiment, antenna 80 includes N annular (ring-like) directors 82 15 disposed above the radiating element 14, where N = 1,2,3,4™. The N directors 82 are configured as vertically spaced parallel polygon-shaped members, shown as concentric rings, although limitation to this geometry of directors 82 is not to be inferred. Other 20 geometric configurations of the directors may be utilized as shown in Figure 13. The ring directors 82 react with the corresponding dipole radiating element 14 to enhance the front-to-side ratio of antenna 10 with improved 25 rolloff. The ring directors 82 are preferably uniformly spaced above the corresponding x-dipole radiating element 14, with the ascending ring 20 WO 2005/122331 PCT/US2005/0I2528 directors 82 having a continually smaller circumference. The ring directors 82 maintain a relatively close spacing with one another being separated by electrically non-conductive spacers, not 5 shown, preferably being spaced less than 0.15 lambda (lambda being the wavelength of the center frequency of the antenna design). Additionally, the grouping of ring directors 82 maintain a relatively close spacing between the bottommost director 82 and the top of the 10 corresponding dipole radiating element 14, preferably less than 0.15 lambda. There are a variety of methods to build the set of planar directors 82, such as molded forms and electrically insulating clips. The set of stacked ring directors 82 may also l5 consist of rings of equal circumference while maintaining similar performance of improved roll-off leading to an improved SPR with the previously stated system benefits while maintaining a similar 3dB beamwidth. 20 Referring now to Figure 11, there is shown at 90 a dual-band antenna including a set of director rings 92 disposed above a stacked Microstrip Annular Ring (MAR) radiator 94. In this view, there are four feedprobes 96 (2 balanced feed pairs) arranged in 25 pairs feeding dual orthogonal polarizations of the MAR radiator 94. The directors 92 in this embodiment of the invention are thin rings stacked above the 21 WO 2005/122331 PCT/US2005/0I2528 respective MAR radiator 94, as shown. Advantageously, this dual-band antenna 90 also has improved element pattern roll-off beyond the 3dB beamwidth thus increasing the SPR while maintaining an equivalent 3dB 5 beamwidth. Referring now to Figure 12, there is shown a dual-band antenna 100 having ring directors 82 and 92. The ring directors 92 above the MAR radiator 94 also interact with the x-dipole radiating element 14 10 and provide some additional beamshaping for the x- dipole radiating element, including improved roll-off of the main beam outside of the 3dB beamwidth as well as improved front-to-back radiation leading to an improved SPR and the system benefits previously l5 mentioned while maintaining a similar 3dB beamwidth. Both the MAR radiator element 94 and the x-dipole radiating element 14 have respective ring directors thereabove. The ring directors 82 for the x-dipole radiating element 14 are also concentric to the ring 20 directors 92 for the MAR radiator 94. The same benefits as discussed earlier for the directors are applicable here as well per frequency band (i.e. improved roll-off beyond the 3dB beamwidth and front-to-back ratio leading to improved SPR. 25 Referring now to Figure 13, there is shown other suitable geometrical configurations of directors 82 22 WO 2005/122331 PCT/US2005/0I2528 and 92, and limitation to a circular ring-like director is not to be inferred. A circle is considered to be an infinitely sided polygon where the term polygon is used in the appending claims. 5 Referring now to Figure 14, there is shown a close-up view of dual band antenna 80 having cross shaped directors 40 extending over the radiating element 14, and the MAR radiator 94 without the associated annular director. 10 Referring now to Figure 15, there is shown a panel antenna 110 having an array of radiating elements 14, each having cross directors 40, alternately provided with the MAR radiators 94, each disposed over common groundplane 112. The advantages 15 of this design include an improved H-plane pattern for the higher frequency radiating element in a dualband topology. The improved H-plane pattern provides improved roll-off beyond the 3dB beamwidth and improved front-to-back ratio. The improved roll-off 20 additionally provides a slight decoupling of the radiators depending on the number of directors incorporated due to lower levels of side and back radiation. 23 WO 2005/122331 PCT/US2005/0I2528 Though the invention has been described with respect to a specific preferred embodiment, many-variations and modifications will become apparent to those skilled in the art upon reading the present 5 application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications. 24 WO 2005/122331 PCT/US2005/012528 WE CLAIM: 1. An antenna, comprising: at least one slant 45 dipole radiating element adapted to generate a beam; and 5 at least one director disposed proximate the at least one dipole radiating element adapted to improve a Sector Power Ratio (SPR) of the beam while maintaining an equivalent 3dB beamwidth. 2. The antenna as specified in Claim 1 wherein 10 the antenna has a Sector Power Ratio of less than 10%. 3. The antenna as specified in Claim 2 wherein the antenna has a Sector Power Ratio of less than 5%. 4. The antenna as specified in Claim 3 wherein l5 the antenna has a Sector Power Ratio of less than 2%. 5. The antenna as specified in Claim 1 comprising at least 2 of the directors. 6. The antenna as specified in Claim 5 wherein at least 2 of the directors are parallel to one 20 another. 7. The antenna as specified in Claim 5 wherein at least some of the directors are uniformly spaced from one another. 25 WO 2005/122331 PCT/US2005/012528 8. The antenna as specified in Claim 7 wherein one of the directors is spaced closer to the radiating element than an adjacent said director. 9. The antenna as specified in Claim 1 wherein 5 the radiating element is a cross dipole radiating element. 10. The antenna as specified in Claim 9 wherein the director has at least 2 members. 11. The antenna as specified in Claim 10 wherein 10 the members are cross-shaped members parallel to the cross dipole radiating element in the vertical direction. 12. The antenna as specified in Claim 1 wherein the at least one director comprises a polygon shaped 15 ring. 13. The antenna as specified in Claim 12, further comprising a plurality of the polygon shaped rings disposed over the radiating element. 14. The antenna as specified in Claim 13 wherein 20 the polygon shaped rings are concentric. 15. The antenna as specified in Claim 14 wherein the polygon shaped rings have a common diameter. 26 WO 2005/122331 PCT/US2005/012528 16. The antenna as specified in Claim 14 wherein the polygon shaped rings have different diameters and form a tapered director. 17. The antenna as specified in Claim 10 wherein 5 the members have different lengths and form a tapered director. 18. The antenna as specified in Claim 1 wherein the antenna has a front-to-side ratio of at least 20 dB. 10 19. The antenna as specified in Claim 1 wherein the antenna has a front-to-back ratio of at least 40 dB. 20. An antenna, comprising: a plurality of tilted groundplanes configured in 15 a "fallen-domino' arrangement; and a plurality of dipole radiating elements disposed above the groundplanes and configured such that the dipole radiating elements define a boresight downtilt. 21. The antenna as specified in Claim 20 wherein 20 the antenna has a beam downtilt, further comprising a feed network coupled to the plurality of dipole radiating elements and adapted to selectively adjust the antenna beam downtilt. 27 WO 2005/122331 PCT/US2005/012528 22. The antenna as specified in Claim 21 wherein the boresight downtilt is defined at approximately a midpoint of an overall beam downtilt. 23. The antenna as specified in Claim 22 wherein 5 the groundplanes are disposed a fixed distance from one another. 24. The antenna as specified in Claim 21 wherein the dipole radiating elements are grouped in pairs, wherein at least one said pair is defined on each of l0 the groundplanes. 25. An antenna comprising a radiating element disposed over a tray having a backside and having at least one groundplane disposed above the tray, the tray having a side wall spaced from the groundplanes 15 and defining a gap therebetween. 26. The antenna as specified in Claim 25 wherein the gap forms a RF choke configured to reduce RF current flowing in the backside of the tray. 27. The antenna as specified in Claim 26 further 20 comprising an RF absorber disposed in the RF choke. 28. The antenna as specified in Claim 25 wherein a height of the tray sidewall is configured to increase a front-to-back ratio of the antenna. 28 WO 2005/122331 PCT/US2005/012528 29. The antenna as specified in Claim 25 further comprising an RF absorber disposed behind the groundplanes adapted to reduce RF current coupling between the groundplanes. 5 30. A dual-band antenna, comprising: a first slant 45 dipole radiating element adapted to generate a first beam at a first frequency; a first director disposed proximate the first radiating element adapted to improve a Sector Power 10 Ratio of the beam while maintaining an equivalent 3dB beamwidth; and a second radiating element disposed proximate the first radiating element and adapted to generate a second beam at a second frequency- 15 31. The dual-band antenna as specified in Claim 30, further comprising a second director disposed proximate the second radiating element adapted to improve the Sector Power Ratio of the second beam while maintaining an equivalent 3dB beamwidth. 20 32. The dual-band antenna as specified in Claim 31 wherein the first director comprises at least two members. 29 WO 2005/122331 PCT/US2005/012528 33. The dual-band antenna as specified in Claim 32 wherein the second director comprises at least two members. 34. The dual-band antenna as specified in Claim 5 33 wherein the first and second directors are disposed over the respective first and second radiating elements. 35. The dual-band antenna as specified in Claim 30 wherein the second radiating element comprises a l0 slant 45 microstrip annular ring radiating element. 36. The dual-band antenna as specified in Claim 30 wherein the first radiating element comprises a cross-shaped radiator. 37. The dual-band antenna as specified in Claim 15 36 wherein the second radiating element comprises a polygon-shaped radiator. 38. The dual-band antenna as specified in Claim 30 wherein the first director comprises at least one cross-shaped member. 20 39. The dual-band antenna as specified in Claim 31 wherein the second director comprises at least one polygon-shaped member. 30 WO 2005/122331 PCT/US2005/012528 40. The dual-band antenna as specified in Claim 37 wherein the first director comprises a plurality of the cross-shaped members. 41. The dual-band antenna as specified in Claim 5 37 wherein the second director comprises a plurality of the polygon-shaped members. 42. The dual-band antenna as specified in Claim 30 wherein the second radiating element encompasses the first radiating element. 10 43. The dual-band antenna as specified in Claim 42 wherein the first radiating element comprises a cross-shaped dipole radiating element. 44. The dual-band antenna as specified in Claim 42 wherein the second radiating element comprises a 15 polygon. 45. An antenna, comprising: a slant 45 dipole radiating element adapted to generate a beam; and director means for directing the beam. 20 46. The dual-band antenna as specified in Claim 45 wherein the director means establishes a Sector Power Ratio of the beam being less than 10%. 31 WO 2005/122331 PCT/US2005/012528 47. The dual-band antenna as specified in claim 45 wherein the director means establishes a Sector Power Ratio of the beam being less than 5%. 48. The dual-band antenna as specified in Claim 5 45 wherein the director means establishes a Sector Power Ratio of the beam being less than 2%. 49. The dual-band antenna as specified in Claim 45 wherein the director means establishes a front-to- back ratio of the beam of at least about 40 dB. 10 50. The dual-band antenna as specified in Claim 45 wherein the director means establishes a front-to-side ratio of the beam of at least about 20 dB. Dated this 2.3rd day 0f November, 2006 G. DEEPAK SRINIWAS OF K & S PARTNERS AGENT FOR THE APPLCIANT 32 DIRECTED DIPOLE ANTENNA ABSTRACT A dual polarized variable beam tilt antenna having a superior Sector Power Ratio (SPR). The antenna may have slant 45 dipole radiating elements including directors, and may be disposed on a plurality of tilted element trays to orient an antenna boresight downtilt. The directors may be disposed above or about the respective dipole radiating elements. The antenna has a beam front-to-side ratio exceeding 20 dB. a horizontal beam front-to-back ratio exceeding 40 dB, a high-roll off, and is operable over an expanded frequency range 33

Documents:

1428-mumnp-2006-abstract(24-11-2006).pdf

1428-MUMNP-2006-ABSTRACT(27-4-2009).pdf

1428-mumnp-2006-abstract(granted)-(26-6-2009).pdf

1428-mumnp-2006-abstract.doc

1428-mumnp-2006-abstract.pdf

1428-MUMNP-2006-CANCELLED PAGES(27-4-2009).pdf

1428-MUMNP-2006-CLAIMS(27-4-2009).pdf

1428-mumnp-2006-claims(complete)-(24-11-2006).pdf

1428-mumnp-2006-claims(granted)-(26-6-2009).pdf

1428-mumnp-2006-claims.doc

1428-mumnp-2006-claims.pdf

1428-mumnp-2006-correspondance-received.pdf

1428-mumnp-2006-correspondence(18-12-2007).pdf

1428-MUMNP-2006-CORRESPONDENCE(27-4-2009).pdf

1428-mumnp-2006-correspondence(ipo)-(8-7-2009).pdf

1428-mumnp-2006-description (complete).pdf

1428-mumnp-2006-description(complete)-(24-11-2006).pdf

1428-MUMNP-2006-DESCRIPTION(COMPLETE)-(27-4-2009).pdf

1428-mumnp-2006-description(granted)-(26-6-2009).pdf

1428-mumnp-2006-drawing(24-11-2006).pdf

1428-MUMNP-2006-DRAWING(27-4-2009).pdf

1428-mumnp-2006-drawing(granted)-(26-6-2009).pdf

1428-mumnp-2006-form 1(24-11-2006).pdf

1428-MUMNP-2006-FORM 1(27-4-2009).pdf

1428-mumnp-2006-form 18(31-1-2007).pdf

1428-mumnp-2006-form 2(27-4-2009).pdf

1428-mumnp-2006-form 2(complete)-(24-11-2006).pdf

1428-mumnp-2006-form 2(granted)-(26-6-2009).pdf

1428-MUMNP-2006-FORM 2(TITLE PAGE)-(27-4-2009).pdf

1428-mumnp-2006-form 2(title page)-(complete)-(24-11-2006).pdf

1428-mumnp-2006-form 2(title page)-(granted)-(26-6-2009).pdf

1428-mumnp-2006-form 26(24-11-2006).pdf

1428-mumnp-2006-form 26(8-1-2007).pdf

1428-mumnp-2006-form 3(18-12-2007).pdf

1428-mumnp-2006-form 3(24-11-2006).pdf

1428-MUMNP-2006-FORM 3(27-4-2009).pdf

1428-mumnp-2006-form 3(31-1-2007).pdf

1428-MUMNP-2006-FORM 5(27-4-2009).pdf

1428-mumnp-2006-form-2.doc

1428-mumnp-2006-form-2.pdf

1428-mumnp-2006-form-5.pdf

1428-mumnp-2006-form-pct-isa-210.pdf

1428-MUMNP-2006-PETITION UNDER RULE 137(27-4-2009).pdf

1428-mumnp-2006-wo international publication report(24-11-2006).pdf