Title of Invention

BROADBAND DUAL POLARIZED BASE STATION ANTENNA

Abstract

Abstract BROADBAND DUAL POLARIZED BASE STATION ANTENNA A dual polarized broadband base station antenna for wireless communication systems is disclosed. The present invention employs a dual polarized boxed arrangement radiation element with high isolation between polarization channels. Plural radiating elements project outwardly from the surface of a ground plane. The antenna elements are paired dipoles.

Full Text

BROADBAND DUAL POLARIZED BASE STATION ANTENNA RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. 119 (e) of U.S. provisional patent application Serial No. 60/787.442, filed on March 30, 2006, incorporated herein by reference in its entirety. This application further claims the benefit under 35 U.S.C. 119 (e) of U.S. provisional patent application Serial- No. 60/799,241, filed on March 3, 2006, incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates to antennas for receiving and/or transmitting electromagnetic signals. More particularly, the present invention relates to base station antennas for wireless communication systems. BACKGROUND OF THE INVENTION Many wireless applications require transmission and/or reception on orthogonal linear polarizations. In some applications, transmission is performed with one polarization and reception is perfonned with an orthogonal polarization in order to provide isolation between the transmitted and received signals. In other application, electromagnetic energy is received on both polarizations and the signals are combined to increase the signal-to-noise ratio, providing polarization diversity gain. Since a wireless telecommunication system can suffer from multi-path fading, diversity reception is often used to address severe multi-path fading. A diversity technique requires at least two signal paths that carry the same information but have uncorrelated multi-path fadings. Several types of diversity reception are used in base stations, including space diversity, direction diversity, polarization diversity, frequency diversity and time diversity. Polarization diversity uses orthogonal polarization to provide uncorretated paths. The sense or direction of linear polarization of an antenna is measured from a fixed axis and can vary, depending on system requirements. In particular, the sense of polarization can range from vertical polarization (0 degrees) to horizontal polarization (90 degrees). Conventionally, the most prevalent types of linear polarization used in wireless systems are those which use vertical/horizontal and. +45°/H45° polarization (slant 45°). When an antenna assembly receives or transmits signals with two normally orthogonal polarizations, such an antenna assembly is referred to as dual polarized antenna assembly. Such dual polarized antennas must meet a certain port-to-port isolation specification. There is a need for improved port-to-port isolation in dual polarized antennas. BRIEF SUMMARY OF THE INVENTION The present invention provides an antenna assembly for receiving and/or transmitting electromagnetic signals, comprising a dual p>olarized radiation element comprising a square arrangement of plural radiating elements, wherein the plural radiating elements form paired dipoles. In one embodiment, the square arrangement of plural radiating elements provides better than 30dB isolation between the polarization channels. Each radiating element comprises a dipole antenna, and the antenna assembly further includes a ground plane wherein each dipole antenna projects outwardly from the ground plane. Each paired dipole comprises a pair of radiating elements with radiating arms in parallel configuration, wherein a common feed line pattern provides a common input to the paired dipole. Further, each radiation element includes two paired dipoles in a box configuration, wherein each paired dipole comprises a pair of radiating elements in parallel configuration, each paired dipole having a common feed line pattern providing a common input to that paired dipole. The radiating elements can be oriented such that one paired dipole provides 45° polarization and another paired dipole provides -45° polarization. in another embodiment, the present invention provides a broadband dual polarized base station antenna comprising a ground section including a ground plane, and a communication means for dual polarized communication of signals with better than 30dB level isolation between polarization channels, wherein said communication means projects outwardly- from, a surface of the ground plane. The communication means comprises at least one radiation element including a dual polarized square arrangement of plural radiating elements, wherein the plural radiating elements form paired dipoles. At least one radiation element comprises plural radiation elements in arranged in a row. in each radiation element, the radiating elements are further oriented such that one paired dipole provides +45° polarization and another paired dipole provides -45° polarization, wherein the plural radiation elements are arrange in a row on the ground plane such that the radiation elements have parallel +45° polarization axis, and parallel -45° polarization axis. In one version, the communication means is configured for operating In the 806 to 960 MHz frequency band, or in the 380 to 470 MHz frequency band, or in tine 1710 to 2170 MHz frequency band, or in one or more of 380 to 470 MHz. 806 to 960 MHz, and 1710 to 2170 MHz frequency bands. In another version, the communication means is configured for operating in one or more of 2.3 QHz. 2.4GHz, 2.5 GHz, 3.5 GHz and 5.8 GHz frequency bands. In another embodiment the present invention provides an antenna assembly for receiving and/or transmitting electromagnetic signals, comprising a ground plane, and plural radiation elements, each radiation element comprising a square arrangement of plural radiating elements, wherein the plural radiating elements project outwardly from a surface of the ground plane, and the plural radiating elements form paired dipoles with a common feed line pattern. Each radiating element comprises a dipole antenna including a first conductor extending transversely from a surface of the ground plane and electrically connected to the ground plane, the first conductor comprising a first radiating arm projecting outwardly therefrom, and a second conductor spaced from the ground plane by a dielectric and extending transversely relative to the surface of the ground plane, the second conductor comprising a second radiating arm projecting outwardly therefrom, wherein the first and second conductors are spaced from one another by a gap, and the first and second radiating arms project outwardly in essentially opposite directions. These and other features, aspects and advantages of the present.invention wiII become understood with., reference to the following description, appended claims and accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1a shows an isometric view of an example dual polarized radiation element with mirrored dipole pairs, in accordance with the present invention. Fig. 1b shows an isometric view of one of the dipole antennas in Fig. 1a. according to an embodiment of the present invention. Fig. 1c shows one of the dipole arms of the dipole antenna in Fig. 1b, according to an embodiment of the present invention Fig. 1d shows another one of the dipole arms of the dipole antenna in Fig. 1c, according to an embodiment of the present invention. Fig. 2 shows an isometric view of plural dual polarized radiation elements configured on a ground plane in horizontal and vertical orientation, according to an embodiment of the present invention. Fig. 3 shows an array of dipole pairs from the radiation elements in Fig. 2, having a common feed iine, according to an embodiment of the present invention. Fig. 4 shows another array of dipole pairs from the radiation elements in Fig. 2, having a common feed iine, according to an embodiment of the present invention. Fig. 5 shows the isometric view of a 45° dipole pair in the dual polarized radiation element of Fig. la, according to an embodiment of the present invention. Fig. 6 shows the isometric view of a -45° dipole pair in the dual polarized radiation element of Fig. 1a, according to an embodiment of the present invention. Fig.7a-c show how examples of using a clip to hold adjacent dipole antennas together, according to the present invention, Fig. 8a-d show a top view of four examples of box dipole arrangements, according to- thepressnt invention. Fig. 9 shows an example 7/16 Din connector to microstrip line transition, according to the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dual polarized broadband base station antenna assembly for wireless communication systems. In one embodiment, the antenna assembly employs a dual polarized boxed arrangement radiation element with improved isolation between polarization channels. The box arrangement (box configuration) provides improved port-to-port isolation (isolation between polarization channels), wherein in one embodiment the isolation level is better than 30dB. The radiation element includes plural dipole antennas, wherein each dipole antenna has a paired strips line feed. The microstrip to paired strips line transition is very broad band. The boxed shape arrangement improves the isolation dramatically. Such antenna design may be used for a "cellular" frequency band e.g. 806 - 960 MHz. Alternatively, the same design may operate at e.g. the 380 - 470 MHz band. Another band is e.g. 1710-2170 MHz. However, the antenna design may also be employed in a number of other frequency bands as well, such as WiMax 2.3 GHz. 2.5 GHz. 3.5 GHz. WiFi 2.4GHz, 5.8 GHz frequency bands, etc. Fig. la shows an example dual polarized boxed arrangement radiation element 1 with mirrored dipoles, for use in a dual polarized antenna with isolation between polarization channels according to the present invention. The radiation element 1 comprises plural dipole antennas (radiating elements) 10 arranged in a general square configuration to provide a boxed arrangement (Fig. la). In a preferred embodiment, the radiation element 1 comprises four dipole antennas 10. As shown in Figs. 1b-c, each dipole antenna 10 includes two arms (radiating members) 18, 20, a ground plate 12 and two electrical conductors/legs 14 and 16. Fig. lb shows an isometric view of a single dipole antenna 10. The amis 18. 20 can be straight or curved. The conductor 16 is attached to ground using the plate 12, with a dipole arm 18 (Fig. 1d) towards one side, while the other conductor 14 is spaced to the ground by a dielectric, such as air, foam, etc., with a dipole arm 20 (Fig. 1c) towards the opposite side of dipole amn 18, therefore forming a dipole configuration. Each dipole arm forms a radiating section. In this example, the conductor 14 and dipole arm 20 are fomned/stamped from a sheet of conductive material, forming an L-shape. Further, the conductor 16 and dipole arm 18 are formed/stamped from a sheet of conductive material, forming an L-shape. The input conductors 14 and 16 are separated by a gap 22 (e.g.. Fig. 8a). The conductor 14 connects a part of the dipole arm 20 to a feed line 24 and the conductor 16 connects a part of the dipole arm 18.to ground via the plate 12. The conductors 14 and 16 form a paired strips transmission tine having an impedance. The arms 18, 20 also have an impedance. The impedance of the paired strips transmission line 14. 16, is adjusted by varying the width of conductor sections 14, 16 and/or the gap 22 therebetween. The specific dimensions vary with the application. As such, the impedance of the corresponding feed section is adjusted to match the intrinsic input impedance of each dipole. The two conductor sections 14, 16 of the dipole antenna form a balanced paired strips transmission line; therefore, it is unnecessary to provide a balun. This provides the antenna 10 with a very wide impedance bandwidth. Also, the antenna 10 has a stable far-field pattern across the impedance bandwidth. Fig. Id shows the dipole arm IB that can be attached to a ground plane via the plate 12 and Fig. 1c shows the dipole arm 20 with the microstrip feed line 24 attached. The feed line 24 (and its extension feed line 11A or 11B) comprises a microstrip feed line spaced from the ground plane by non-conductor such as air dielectric (e.g., 31 in Fig. 9). A similar spacing mechanism can be used for spacing the conductor 14 from the ground plane 5. The impedance of the microstrip line is adjusted by varying the width of the line 24, and/or the space between the microstrip line to the ground plane. The feed line 24 is shown as a unitary element of the conductor 14. The conductor section 16 can be connected to the ground plane by any suitable fastening device such as a nut and bolt, a screw, a rivet, or any suitable fastening method including soldering, welding, etc. The suitable connection provides both an electrical and mechanical connection between the conductor 16 and ground plane. Fig. 2 shows another example wherein plural radiation elements 2 are configured on a ground plane 5, according to the present invention. Each dipole antenna 10 forms a dipole, and has two neighboring (adjacent) orthogonal dipole antennas in the box shape of a radiation element 2, and one parallel (across) dipole antenna in said-box shape. The box dipole formed by each dipole antenna. 10.couples strongly with its neighboring orthogonal dipoles 10. However, if two parallel dipoles are fed with equal phase and amplitude and are arranged symmetrically with respect to the orthogonal dipoie(s), then the coupled energy from one neighboring dipole will be of equal magnitude and opposite phase as energy from the other neighboring dipole. Then the two coupled fields therefore cancel out. The isolation between two polarization channels will be improved dramatically because of the boxed dipole arrangement. The antennas 10 are paired with a common feed pattern (e.g., 11A or 11B) providing a common input. Rg. 5 shows a pair of dipole antennas ID forming a +45° polarization radiating dipole antenna pair (dipole pair A) with a common feed line 11 A. Fig. 6 shows another pair of dipole antennas 10 forming a -45° polarization radiating dipole antenna pair (dipole pair B) with a common feed line 11B. The dipole pairs A and B are arranged to obtain the square configuration ±45° polarization radiation element 1 in Fig. la. Plural radiation elements 1 can be arranged in an array. Fig. 3 shows an array 13A of four dipole pairs 17A having a common feed line 11 A. Each dipole pair 17A comprises a pair of antennas 10. Fig. 4 shows another array 13B of four dipole pairs 17B, having a common feed line 11B. The arrays 13A and 138 are arranged to obtain the configuration of four radiation elements 1 shown in Fig. 2. The ground plane 5 has a length and a vertical axial along the length, and the dipole radiating antennas 10 project outwardly (transversely) from a surface of the ground plane 5. Fig. 7a shows how a non-conducting clip 15 (e.g., plastic dip) may be employed to hold a pair of adjacent (orthogonal) dipole antennas 10 together, to form an essentially square configuration for four dipole antennas 10. As shown in Fig. 7b, each clip 15 Is L-shaped with ends 15A, 15B, which as Fig. 7c shows by example in more detail, snap into holes in the arms 20, 18. respectively of two orthogonal dipole antennas iO^to hold the orthogonal-antennas together. As those sicilled in the art will recognize, other ways of hold the orthogonal antennas together are possible. As such, the present invention is not limited to the examples shown in Figs. 7a-c. Figs. 8a-d show top views of four example, box dipole antenna arrangements, with the same box dipole configuration orientation, according to the present invention. Specifically, Fig. Ba shows four dipole antennas 10K, 10L, 10M and 10N arranged as a square configuration ±45° polarization radiation element 1A. The antennas 10K and 10L form a +45° polarization dipole pair A, and the antennas 10M and 10N form a -45° polarization dipole pair S. The paired dipole is mirrored, wherein all the ground dipoles are attached to ground through ground plate 12, which is mirrored by the -•■ or - 45 degree axis. The arm 18 of each dipole antenna extends from the respective conductive leg in planar form. Similarly, the arm 20 of each dipole antenna extends from the respective conductive leg as a flat element, in Figs. 8b-d, the arms IB. 20 of the antenna 10K are in the same plane. The same holds for the antennas 10L. 10M and ION. The plane of the amns 18. 20 of the antenna 10K is parallel to the plane of the amis 18. 20 of antenna 10L. Similarly, the plane of the arms 18, 20 of the antenna 10M is parallel to the plane of the arms 18, 20 of antenna ION. Fig. 8a also shows -1-45' polarization axis and -45° polarization axis in relation to tlie orthogonal X, Y and Z axis in three dimensions. The -45° axis is perpendicular to the plane of the arms of the antennas 10K and 10L. The -1-45° axis is perpendicular to the plane of the arms of the antennas 10M and ION. The Y and Z axis form a Y-Z plane which is in the plane of the drawing sheet. The +/-45' axis are in the Y-Z plane. The • Fig. 8b shows four dipole antennas 10K. 10L, 10M and ION, arranged as a square configuration ±A5' polarization radiation element 1B, wherein the antennas 10K and 10L form a +45°polarization dipole pair A, and antennas 10M and 10N form a -45° polarization dipole pair B. The arm 18 of each dipole antenna includes an essentially S-shaped section 19 extending from the respective conductive leg. Similarly, the arm 20 of each dipole antenna includes an essentially S-shaped section 19 extending from the respective conductive leg. The section 19 allows maintaining symmetry of the box dipole configuration, and it allows improving the isolation between those input ports or polarizations. The arms 18, 20 of the antenna 10K are in the same plane. The same holds for the antennas 10L, 10M and ION. The plane of the arms 18.20 of the antenna 10K is parallel to the plane of the anns 18, 20 of antenna 10L. Similariy; the plane of the arms 18, 20 of the antenna 10M is parallel to the plane of the arms 18, 20 of antenna 1.0N. The -45° axis is perpendicular to the plane of the arms of the antennas 10K and 10L. The +45° axis is perpendicular to the plane of the arms of the antennas 10M and 10N. Plural radiation elements IB can be arranged in an array along their Y-axis on a ground plane which is in the Y-Z plane of al the radiation elements IB. Fig. 8c shows four dipole antennas 10K. 10L. 10M and ION, arranged as a square configuration ±45° polarization radiation element 1C similar to Fig. la, vAherein antennas 10K and 10L form a +45° polarization dipole pair A, and antennas 10M and ION form a -45° polarization dipole pair B. The arm 18 of each dipole antenna includes an essentially S-shaped section 19 extending from the respective conductive leg. However, the arm 20 of each dipole antenna is flat extending from the respective conductive leg. The section 19 allows maintaining symmetry of the-box dipole configuration,-and Jt.allows improving, the .isolation between those input ports or polarizations. The arms 18, 20 of the antenna 10K are in the same plane. The same holds for the antennas 10L, 10M and ION. The plane of the arms 18, 20 of the antenna 10K is parallel to the plane of the arms 18, 20 of antenna 10L Similarly, the plane of the arms 18, 20 of the antenna 10M is parallel to the plane of the arms 18, 20 of antenna ION. The -45° axis is perpendicular to the plane of the arms of the antennas 10K and 10L. The -1-45° axis is perpendicular to the plane of the arms of the antennas 10M and ION. Plural radiation elements 1C can be arranged in an array along their Y-axis on a ground plane which is in the Y-Z plane of al the radiation elements 1C. Fig. 8d shows four dipole antennas 10K, 10L, 10M and ION, anranged as a square configuration ±45° polarization radiation element 1D, wherein antennas 10K and 10L form a +45° polarization dipole pair A, and antennas 10M and 10N form a -45° polarization dipole pair B. The arm 20 of each dipole antenna includes an essentially S-shaped section 19 extending from the respective conductive leg. However, the arm 18 of each dipole antenna is flat extending from the respective conductive leg. The section 19 allows maintaining symmetry of the box dipole configuration, and it allows improving the isolation between those input ports or polarizations. The arms 18, 20 of the antenna 10K are in the same plane. The same holds for the antennas 10L, 10M and ION. The plane of the arms 18, 20 of the antenna 10K is parallel to the plane of the arms 18, 20 of antenna 10L. Similarly, the plane of the arms 18. 20 of the antenna 10M is parallel to the plane of the arms 18, 20 of antenna 10N. The -45° axis is perpendicular to the plane of the arms of the antennas 10K and 10L. The +45° axis is perpendicular to the plane of the anns of the antennas 10M and 10N. Ptural radiation elements 1D can be arranged in an an^y along their Y-axis on a ground plane which is in the Y-Z piane of al the radiation elements 1D. Fig. 9 shows an example connector 30 for direct coupling to each feed Hne (e.g.. air microstrip lines 11 A, 11B) and ground plane 5. The connector 30 includes an electrically-conductive-cylindrica threaded-section 32 for receiving a coaxial-cable, a conductive plate 34 for electrically coupling the section 32 to the ground plane 5, and an axial conductor 36 for electrical coupling to a feed line such as feed line 11 A. At least a portion of the conductor 36 is threaded for fostening to the feed line 11A via a nut 35, and spaced from the ground plane 5 via an electrically insulating washer 37. The conductor 36 is covered by the insulation sleeve 38 for electrical isolation from the conductive plate 34 and the ground plane 5. The feed line 11A is space from the ground plane 5 by a dielectric sleeve 31 which is held in place between the feed line 11A and the ground piane 5 by an electrically insulating (non-conductive) screw 33. The connector 30 can comprise a modified 7/16 Din connector, which eliminates the typical RG401 input cable cost and assembly costs, and also eliminate the coaxial cable to microstrip transition cost and assembly cost. Another connector 30 can be used for connecting another input to the feed line 11B. In a similar fashion. The teachings of Application Serial No. 60/799,241, filed March 3, 2006, for "Broadband vertical polarized base station antenna", the disclosure of which is incorporated herein by reference, may also be employed. The illustrated embodiments are capable of a variety of modifications. Therefore, further aspects of the invention will be appreciated by those skilled in the art. WHAT IS CLAIMED IS: 1. An antenna assembly for receiving and/or transmitting electromagnetic signals, comprising: a dual polarized radiation element comprising a square arrangement of plural radiating elements; wherein the plural radiating elements form paired dipoles. 2. The antenna assembly of claim 1, wherein each radiating element comprises a-dipoleantenna. 3. The antenna assembly of claim 2, further comprising a ground plane wherein each dipole antenna projects outwardly from the ground plane. 4. The antenna assembly of claim 1 wherein each paired dipole comprises a pair of radiating elements with radiating arms in parallel configuration, wherein a common feed line pattern provides a common input to the paired dipole. 5. The antenna assembly of claim 4 wherein each radiation element includes two paired dipoles in a box configuration, wherein each paired dipole comprises a pair of radiating elements in parallel configuration, each paired dipole having a common feed line pattern providing a common input to that paired dipole. 6. The antenna assembly of claim 4 wherein the radiating elements are further oriented such that one paired dipole provides -45° polarization and another paired dipole provides -45° polarization. 7. The antenna assembly of claim 1 wherein- the square arrangement of plural radiating elements provides better than 30dB isolation between the polarization channels. I 8. A broadband dual polarized base station antenna comprising: a ground section including a ground plane; communication means for dual polarized communication of signals with better than 30dB level isolation between polarization channels; wherein said communication means projects outwardly from a surface of the ground plane. 9. The base station antenna of claim 8 wherein said communication means comprises at least one radiation element including a dual polarized square arrangement of plural radiating elements, -wherein the plural radiating elements form paired dipoles. 10. The base station antenna of claim 9 wherein said at least one radiation element comprises plural radiation elements in arranged in a row. 11. The base station antenna of claim 9 wherein in each radiation element, the radiating elements are further oriented such that one paired dipole provides -45° polarization and another paired dipole provides -45° polarization, wherein the plural radiation elements are arrange in a row on the ground plane such that the radiation elements have parallel +45° polarization axis* and parallel -45° polarization axis. 12. The base station antenna of claim 8 wherein the communication means is configured for operating in the 806 to 960 MHz frequency band. 13. The base station antenna of claim 8 wherein the communication means is configured for operating in the 380 to 470 MHz frequency band. 14. The base station antenna of claim 8 wherein the communication means is configured for operating in the 1710 to 2170 MHz frequency band. 15. The base station antenna of claim 8 wherein the communication means is configured for operating In one or more of 380 to 470 MHz, 806 to 960 MHz, and 1710 to 2170 MHz frequency bands. 16. The base station antenna of claim 8 wherein the communication means is configured for operating in one or more of 2.3 GHz, 2,4GHz, 2.5 GHz, 3.5 GHz and 5.8 GHz firequency bands. 17. An antenna-assembly for- receiving-and/or transmitting electromagnetic signals, comprising: a ground plane; plural radiation elements, each radiation element comprising a square arrangement of plural radiating elements, wherein the plural radiating elemente project outwardly from a surface of the ground plane, and the plural radiating elements form paired dipoles with a common feed line pattem; each radiating element comprising a dipoie antenna including: a first conductor extending transversely from a surface of the ground plane and electrically- connected to the ground plane, the first conductor comprising a first radiating arm projecting outwardly therefrom; a second conductor spaced from the ground plane by a dielectric and extending transversely relative to the surface of the ground plane, the second conductor comprising a second radiating arm projecting outwardly therefrom; wherein the first and second conductors are spaced from one another by a gap, and the first and second radiating arms project outwardly in essentially opposite directions. 18. The antenna assembly of claim 17 wherein the first and second radiating arms are essentially in the same plane. 19. The antenna assembly of claim 18 wherein each paired dipole comprises a pair of dipole antennas with radiating arms in parallel configuration and having a common feed line, each feed line comprising a microstrip feed line coupled to said first conductor, and spaced from said ground plane by an air dielectric. 20. The antenna assembly of claim 17 wherein in each radiation element, each paired dipole comprises a pair of radiating elements with radiating arms in parallel configuration, such that a common feed line pattem provides a common input to the paired dipole. 21. The antenna assembly of claim 20 wherein each radiation element includes two paired dipoles in a box configuration, wherein each paired dipole comprises a pair of radiating elements in parallel configuration, each paired dipole having a common feed line pattem providing a common input to that paired dipole. 22. The antenna assembly of claim 21 wherein in each radiation element, the radiating elements are further oriented such that one paired dipole provides +45° polarization and another paired dipole provides -45° polarization. 23. The antenna assembly of claim 17 wherein the radiation elements are arranged in a row. 24. The antenna assembly of claim 23 wherein the plural radiation elements are arranged in a row onthe ground plane such that the radiation elements have parallel +45° polarization axis, and parallel -45° polarization axis. 25. The antenna assembly of claim 17 wherein the square arrangement of plural radiating elements provides better than 30dB isolation between the polarization channels. 26. The antenna assembly of claim 17 wherein the first and second radiating arms are essentially In the same plane. 27. The antenna assembly of claim 26 wherein each paired dipole comprises a pair of radiating elements in parallel configuration having a common feed line, each feed line comprising a microstrip feed line coupled to said first conductor, and spaced from said ground plane by an air dielectric. 28. The antenna assembly of claim 26 wherein: the first conductor and the first radiating arm form an essentially L-shape; and the second conductor and the second radiating arm form an essentially L-shape. 29. The antenna assembly of claim 26 wherein: the first conductor and the first radiating arm are formed from a sheet of conductive material; and the second conductor and the second radiating arm are formed from a sheet of conductive material. 30. The antenna assembly of claim 26 wherein the first and second conductors are spaced in essentially parallel relationship, forming a balanced paired strips transmission line. 31. The antenna assembly of claim 30 wherein the impedance of the paired strips transmission line is adjusted by adjusting the width of the conductor and/or gap between the conductors. 32. The antenna assembly of claim 26 wherein the Impedance of the feed line is adjusted to match input impedance of each radiating ami. 33. The antenna assembly of claim 32 wherein the impedance of the microstrip line is adjusted by adjusting the width of the microstrip line and/or the space between the microstrip line and the ground plane.

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5874-CHENP-2008 AMENDED CLAIMS 18-11-2014.pdf

5874-CHENP-2008 EXAMINATION REPORT REPLY RECEIVED 18-11-2014.pdf

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5874-chenp-2008 abstract.pdf

5874-chenp-2008 claims.pdf

5874-chenp-2008 correspondnece-others.pdf

5874-chenp-2008 description(complete).pdf

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