阅读说明：本技术 用于具有阻挡共模辐射寄生的内置柄过滤器的基站天线的双极化辐射元件 (Dual polarized radiating element for a base station antenna with a built-in stalk filter blocking common mode radiation parasitics ) 是由 M·V·瓦奴斯法德拉尼 于 2020-03-17 设计创作，主要内容包括：天线包括辐射器和馈电柄,所述馈电柄由第一馈电路径和第二馈电路径电耦合到所述辐射器。所述馈电柄包括共模带阻滤波器,所述共模带阻滤波器具有电连接到所述第一馈电路径和所述第二馈电路径的第一端口和第二端口、电耦合到所述第一端口的第一电感器和电耦合到所述第二端口的第二电感器。所述共模带阻滤波器被配置成使得电耦合到所述第一端口的第一阻抗等于Z-(1),并且电耦合到所述第二端口的第二阻抗等于Z-(2),其中：Z-(1)＝R-(1)+jωL-(1)+jωM(I-(2)/I-(1))；Z-(2)＝R-(2)+jωL-(2)+jωM(I-(1)/I-(2))；M≈L-(1)≈L-(2)；R-(1)和R-(2)是第一电感器和第二电感器的电阻；L-(1)和L-(2)是第一电感器和第二电感器的电感；M是第一电感器与第二电感器之间的互感；I-(1)和I-(2)是流入第一端口和第二端口的第一电流和第二电流；并且ω是第一电流和第二电流的角频率。(The antenna includes a radiator and a feed stalk electrically coupled to the radiator by a first feed path and a second feed path. The feed stalk includes a common mode band reject filter having first and second ports electrically connected to the first and second feed paths, a first inductor electrically coupled to the first port, and a second inductor electrically coupled to the second portThe second inductor of (2). The common mode band reject filter is configured such that a first impedance electrically coupled to the first port is equal to Z 1 And a second impedance electrically coupled to the second port is equal to Z 2 Wherein: z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 )；Z 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 )；M≈L 1 ≈L 2 ；R 1 And R 2 Is the resistance of the first inductor and the second inductor; l is 1 And L 2 Is the inductance of the first inductor and the second inductor; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 Is a first current and a second current flowing into the first port and the second port; and ω is the angular frequency of the first and second currents.)

1. An antenna, comprising:

a radiator comprising first and second radiator arms supported in front of a substrate by a feed stalk, the feed stalk comprising a first feed path electrically coupled to the first radiator arm, a second feed path electrically coupled to the second radiator arm, and a common mode band reject filter having first and second ports electrically connected to the first and second feed paths, respectively.

2. The antenna of claim 1, wherein the common mode band reject filter includes a pair of mutually coupled inductors therein.

3. The antenna defined in claim 2 wherein the pair of mutually coupled inductors are positioned intermediate the base and distal ends of the feed stalk.

4. The antenna of claim 2, wherein the pair of mutually coupled inductors comprises: a first inductor having a first current-carrying terminal electrically coupled to a first port of the common mode band reject filter; and a second inductor having a first current carrying terminal electrically coupled to a second port of the common mode band reject filter.

5. The antenna defined in claim 3 wherein the feed stalk comprises a printed circuit board having patterned metallization on first and second opposing faces of the printed circuit board; and wherein the pair of mutually coupled inductors are defined at least in part by patterned metallization on first and second opposing faces of the printed circuit board.

6. The antenna of claim 3, wherein the feed stalk comprises a printed circuit board; wherein the pair of mutually coupled inductors comprises a first inductor and a second inductor; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

7. The antenna of claim 6, wherein the first feed path is electrically connected to the first inductor; and wherein the second feed path is electrically connected to the second inductor by a plated through hole in the printed circuit board.

8. The antenna of claim 2, wherein the feed stalk comprises a printed circuit board having patterned metallization on first and second opposing faces of the printed circuit board; and wherein the pair of mutually coupled inductors are defined at least in part by patterned metallization on first and second opposing faces of the printed circuit board.

9. The antenna of claim 2, wherein the feed stalk comprises a printed circuit board; wherein the pair of mutually coupled inductors comprises a first inductor and a second inductor; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

10. The antenna of claim 9, wherein the first feed path is electrically connected to the first inductor; and wherein the second feed path is electrically connected to the second inductor by a plated through hole.

11. The antenna of claim 4, wherein the common-mode band-stop filter is configured such that a first impedance electrically coupled to the first port is equal to Z₁And a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the same asA mutual inductance between an inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; and ω is the angular frequency of the first and second currents.

12. The antenna of claim 11, wherein the antenna is a box dipole antenna having first through fourth feed ports; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

13. The antenna of claim 4, wherein the antenna is a box dipole antenna having first through fourth feed ports; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

14. The antenna of claim 1, wherein the antenna is a box dipole antenna having first through fourth feed ports; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

15. The antenna of claim 11, wherein the antenna is a loop antenna having at least a first feed port; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

16. The antenna of claim 4, wherein the antenna is a loop antenna having at least a first feed port; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

17. The antenna of claim 1, wherein the antenna is a loop antenna having at least a first feed port; and wherein the first feed port is electrically coupled to the first feed path and the second feed path by the common mode band reject filter.

18. A box dipole antenna comprising:

a first dipole radiator having first and second dipole arms electrically coupled to respective first and second ports of a first common-mode band-stop filter, the first common-mode band-stop filter configured such that a first impedance therein electrically coupled to the first port is equal to Z₁And wherein a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; and ω is the angular frequency of the first and second currents.

19. The antenna of claim 18, wherein the first common mode band-stop filter is integrated into a first feed stalk electrically coupled to a first end of the first dipole arm and a first end of the second dipole arm; and wherein the first feed stalk supports the first dipole radiator at least partially in front of an underlying substrate.

20. The antenna defined in claim 18 further comprising first through fourth feed handles electrically coupled to first through fourth corners of the box-shaped dipole antenna, the first through fourth feed handles including respective first through fourth common-mode band-stop filters integrated therein.

21. The antenna of claim 20, wherein the first through fourth common-mode band-stop filters have the same impedance characteristics.

22. The antenna of claim 19, wherein the first feed stalk comprises a printed circuit board; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

23. The antenna of claim 22, wherein the first dipole arm is electrically coupled to the first inductor; and wherein the second dipole arm is electrically coupled to the second inductor by a plated via in the printed circuit board.

24. An antenna, comprising:

a radiator; and

a feed stalk including a common mode band reject filter having first and second ports electrically connected to first and second radiating elements, respectively, within the radiator.

25. The antenna of claim 24, wherein the common mode band reject filter includes a pair of mutually coupled inductors therein.

26. The antenna defined in claim 25 wherein the pair of mutually coupled inductors are disposed intermediate the top and bottom of the feed stalk.

27. The antenna of claim 25, wherein the pair of mutually coupled inductors comprises: a first inductor having a first current-carrying terminal electrically coupled to a first port of the common mode band reject filter; and a second inductor having a first current carrying terminal electrically coupled to a second port of the common mode band reject filter.

28. The antenna defined in claim 26 wherein the feed stalk comprises a printed circuit board having patterned metallization on first and second opposing faces of the printed circuit board; and wherein the pair of mutually coupled inductors are defined at least in part by patterned metallization on first and second opposing faces of the printed circuit board.

29. The antenna defined in claim 26 wherein the feed stalk comprises a printed circuit board; wherein the pair of mutually coupled inductors comprises a first inductor and a second inductor; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

30. The antenna of claim 29, wherein the first feed path is electrically connected to the first inductor and the second feed path is electrically connected to the second inductor by a plated through hole in the printed circuit board.

31. The antenna defined in claim 25 wherein the feed stalk comprises a printed circuit board having patterned metallization on first and second opposing faces of the printed circuit board; and wherein the pair of mutually coupled inductors are defined at least in part by patterned metallization on first and second opposing faces of the printed circuit board.

32. The antenna defined in claim 25 wherein the feed stalk comprises a printed circuit board; wherein the pair of mutually coupled inductors comprises a first inductor and a second inductor; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

33. The antenna of claim 32, wherein the first feed path is electrically connected to the first inductor and the second feed path is electrically connected to the second inductor by a plated through hole.

34. The antenna of claim 27, wherein the common-mode band-stop filter is configured such that a first impedance electrically coupled to the first port is equal to Z₁And a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; and ω is the angular frequency of the first and second currents.

35. The antenna according to any of claims 24 to 34, wherein the radiator is selected from a box dipole radiator and a loop radiator.

36. An antenna, comprising:

a radiator electrically coupled to the arrangementA respective first port and second port of a common mode band-stop filter in a feed signal path of the antenna, the common mode band-stop filter configured such that a first impedance therein electrically coupled to the first port is equal to Z₁And wherein a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；M≈L₁≈L₂；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; the symbol "≈" designates equality within ± 10%; and ω is the angular frequency of the first and second currents.

37. The antenna defined in claim 36 wherein the common-mode band-stop filter is integrated into a feed stalk that is electrically coupled to the radiator and at least partially supports the radiator in front of an underlying substrate.

38. The antenna defined in claim 37 wherein the feed stalk comprises a printed circuit board; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

39. The antenna defined in claim 36 wherein the common-mode band-stop filter is integrated into a feed stalk that is electrically coupled to the radiator; wherein the feed stalk comprises a printed circuit board; wherein the first inductor is defined at least in part by patterned metallization on a first side of the printed circuit board; and wherein the second inductor is defined at least in part by patterned metallization on a second side of the printed circuit board opposite the first side.

40. The antenna according to any of claims 36 to 39, wherein the radiator is selected from a box dipole radiator and a loop radiator.

41. An antenna, comprising:

a radiator configured to receive first and second differential mode feed signals from respective first and second ports of a common mode band reject filter comprising first and second mutually coupled inductors.

42. The antenna of claim 41, wherein said first inductor and said second inductor are matched to have equivalent inductance; and wherein a magnitude of a mutual inductance between the first inductor and the second inductor is equal to an inductance of the first inductor and the second inductor.

43. An antenna feed stalk, comprising:

a printed circuit board having a common mode band reject filter embedded therein, the common mode band reject filter including a first port and a second port, a first inductor electrically coupled to the first port, and a second inductor electrically coupled to the second port.

44. The antenna feed stalk of claim 43, wherein the common mode band-stop filter is configured such that a first impedance electrically coupled to the first port is equal to Z₁And a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；M≈L₁≈L₂；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; the symbol "≈" designates equality within ± 10%; and ω is the angular frequency of the first and second currents when the antenna feed stalk is implemented within an active antenna.

Technical Field

The present invention relates to radio communication and antenna arrangements, and more particularly to a dual polarized antenna for cellular communication and a method of operating a dual polarized antenna.

Background

Cellular communication systems are well known in the art. In a typical cellular communication system, a geographic region is typically divided into a series of regions, commonly referred to as "cells," which are served by respective base stations. Each base station may include one or more Base Station Antennas (BSAs) configured to provide bi-directional radio frequency ("RF") communications with mobile users within a cell served by the base station. In many cases, each base station is divided into "sectors. In the most common configuration possible, the hexagonal shaped cell is divided into three 120 ° sectors and each sector is served by one or more base station antennas, which may have an azimuthal Half Power Beamwidth (HPBW) of approximately 65 °, providing sufficient coverage for each 120 ° sector. Typically, the base station antenna is mounted on a tower or other elevated structure, with the radiation pattern (also referred to as an "antenna beam") directed outwardly therefrom. The base station antenna is typically implemented as a linear or planar phased array of radiating elements.

Moreover, to accommodate the increasing cellular traffic, cellular operators have added cellular service in various frequency bands. While in some cases a single linear array of so-called "wideband" radiating elements may be used to provide service in multiple frequency bands, in other cases it may be necessary to use different linear arrays of radiating elements in a multi-band base station antenna to support service in additional frequency bands.

One conventional multi-band base station antenna design includes at least one linear array of relatively "low band" radiating elements that may be used to provide service in some or all of the 617-960MHz frequency band. In addition, to reduce cost and provide a more compact antenna, each of these "low band" radiating elements may be configured to surround a corresponding opposing "high band" radiating element for providing service in some or all of the 1695-.

A conventional box-shaped dipole radiating element may comprise four dipole radiators arranged to define a box-like shape. The four dipole radiators may extend in a common plane and may be mounted in front of a reflector which may extend parallel to the common plane. A so-called feed stem may be used to mount the four dipole radiators forward from the reflector and to pass RF signals between the dipole radiators and other components of the antenna. In some of these conventional box-shaped dipole radiating elements, a total of eight feed handles (4x2) may be provided and may be connected to the box-shaped dipole radiators at the corners of the box.

For example, as shown by fig. 1A-1B, a conventional multi-band radiator 10 for a base station antenna may include a relatively high-band radiating element 10a centered on and surrounded on four sides by a relatively low-band radiating element 10B configured as a box-shaped dipole radiating element ("box-shaped dipole"). RF signals can be fed to the four dipole radiators of a conventional box-shaped dipole radiating element through the feed handles at the two opposite and "excited" corners of the "box", as shown in fig. 1A. In response to Differential Mode (DM) currents fed to two excited "differential mode" ports, a Common Mode (CM) current is automatically forced in response to two diametrically opposed un-excited corners of the cartridge. And, since these common mode currents radiate as monopoles on these "un-excited" feed handles, the overall radiation pattern of the box-shaped dipole 10B is effectively a combination of two dipoles and two monopoles (with "nulls"), as shown in the simplified radiation pattern of fig. 1B. Unfortunately, radiation from monopole operation can be highly undesirable when designing a box dipole radiator. For example, although the common mode current is radiated at the same time as the differential mode current in the box dipole 10b, the azimuth angle HPBW of the box dipole 10b can be expected to be slightly reduced because there are two nulls caused by the monopole radiator, the concurrent co-polarized radiation pattern of the box dipole 10b can be expected to exhibit an elevated "shoulder" in the radiation pattern, which can significantly reduce overall antenna performance.

Referring now to fig. 2A-2B, a conventional cross-polarized box-shaped dipole radiating element 20, 20' (with inwardly angled feed stalk and thus angled monopole) is shown, which operates in a similar manner with respect to the low-band radiating element 10B of fig. 1A. Thus, as shown, excitation of a first pair of diametrically opposed "differential mode" ports of the box-shaped dipole radiating element 20, 20' may induce a Common Mode (CM) current in a corresponding second pair of ports, which results in a single-pole type radiation from a pair of tilted monopoles. Also, as also shown by fig. 2A, this single-pole type radiation may result in the creation of undesirable "shoulders" (S) in the azimuthal radiation pattern associated with the box dipole 20.

Disclosure of Invention

A dual-polarized radiating element for a Base Station Antenna (BSA) may suppress common-mode radiation parasitics using a stem-based filter. According to some embodiments of the invention, the antenna radiating element is provided with a first radiator arm and a second radiator arm, which may be supported by the feed stalk in front of the substrate. The feed stalk includes a first feed path electrically coupled to the first radiator arm, a second feed path electrically coupled to the second radiator arm, and a common mode band reject filter having first and second ports electrically connected to the first and second feed paths, respectively. The common mode band reject filter includes a pair of coupled inductors. In some embodiments of the invention, the pair of coupled inductors may be disposed intermediate the base and the distal end of the feed stalk.

The pair of coupled inductors comprising: (i) a first inductor having a current-carrying terminal electrically coupled to a first port of the common mode band reject filter, and (ii) a second inductor having a current-carrying terminal electrically coupled to a second port of the common mode band reject filter. The feed stalk may also be configured as a printed circuit board having patterned metallization on first and second opposing faces thereof, and the pair of coupled inductors may be defined by the patterned metallization on the first and second opposing faces of the printed circuit board. Additionally, a first feed path may be electrically connected to a first inductor of the pair of coupled inductors, and the second feed path may be electrically connected to a second inductor of the pair of coupled inductors by a plated through hole in the printed circuit board.

According to an additional embodiment of the invention, the common mode band reject filter is configured such that a first impedance electrically coupled to the first port is equal to Z₁A second impedance electrically coupled to the second port equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; and ω is the angular frequency of the first and second currents. These impedances Z₁And Z₂Is configured as I₁Is equal to I₂While blocking common-mode signals with a high frequency-dependent response, but when I₁Is equal to-I₂Is selective andeffectively passing differential mode signals with very low resistance.

In other embodiments of the present invention, the antenna is configured as a box-shaped dipole antenna having first through fourth feed ports in communication with respective first through fourth corners of the box-shaped dipole. A first feed port is disposed at a first corner and is electrically coupled to the first and second feed paths by the common mode band-stop filter. In other embodiments of the invention, the antenna is configured as a loop antenna having at least a first feed port electrically coupled to the first and second feed paths by a common mode band reject filter.

In accordance with additional embodiments of the present invention, a box dipole antenna is provided that includes a first dipole radiator having first and second dipole arms electrically coupled to respective first and second ports of a first common mode band reject filter. The first common-mode band-stop filter is configured such that a first impedance therein electrically coupled to the first port is equivalent to Z₁Wherein a second impedance electrically coupled to the second port is equal to Z₂Wherein: z₁＝R₁+jωL₁+jωM(I₂/I₁)；Z₂＝R₂+jωL₂+jωM(I₁/I₂)；R₁And R₂Resistances of the first inductor and the second inductor, respectively; l is₁And L₂The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is₁And I₂A first current and a second current flowing into the first port and the second port, respectively; and ω is the angular frequency of the first and second currents. In addition, a first common-mode band-stop filter may be integrated into a first feed stalk that: (i) electrically coupled to a first end of the first dipole arm and a first end of the second dipole arm, and (ii) supporting the first dipole radiator on a substrate (e.g., a ground plane reflector of a base station antenna)) In front of the vehicle.

According to still other embodiments of the present invention, there is provided an antenna including a radiator (e.g., a ring dipole, a box dipole, etc.) and a feed stalk. This feed stalk, which is electrically coupled to the radiator by the first and second feed paths, includes a common mode band reject filter having first and second ports electrically connected to the first and second feed paths, respectively. In some of these embodiments of the invention, the common mode band reject filter comprises a pair of coupled inductors therein, which may be disposed intermediate the base and distal ends of the feed stalk. The pair of inductors includes: a first inductor having a first current-carrying terminal electrically coupled to a first port of the common mode band reject filter; and a second inductor having a first current carrying terminal electrically coupled to a second port of the common mode band reject filter.

In some of these embodiments of the invention, the feed stalk may include a printed circuit board having patterned metallization on first and second opposing faces thereof, and the pair of coupled inductors may be defined at least in part by the patterned metallization on the first and second opposing faces of the printed circuit board. Additionally, the first feed path may be electrically connected to a first inductor of the pair of coupled inductors, and the second feed path may be electrically connected to a second inductor of the pair of coupled inductors by a plated through hole in the printed circuit board.

Drawings

Fig. 1A is a schematic diagram of a multi-band radiator comprising a high-band radiating element surrounded by a low-band box-shaped dipole radiating element, showing simulated differential and common mode currents therein, according to the prior art.

Fig. 1B shows Differential Mode (DM) and Common Mode (CM) radiation patterns of a box-shaped dipole antenna according to the prior art.

Fig. 2A shows a conventional box-shaped dipole radiating element with a tilted monopole, and a simulated azimuth radiation pattern with an undesirable shoulder.

Fig. 2B shows a conventional sheet metal box-shaped dipole radiating element with a tilted monopole, and a simulated radiation pattern highlighting the undesirable shoulders.

Fig. 3A is a perspective view of a loop antenna having a feed stalk including a common mode band reject filter according to an embodiment of the present invention.

Fig. 3B is a perspective view of a feed stalk including a multilayer Printed Circuit Board (PCB) according to an embodiment of the present invention.

Fig. 3C is a front view of the feed stalk of fig. 3B showing patterned metallization on the front side of the printed circuit board, in accordance with embodiments of the present invention.

Fig. 3D is a front view of the feed stalk of fig. 3B, but with all of the patterned metallization on the front side of the printed circuit board removed, and only the patterned metallization on the back side of the printed circuit board visible (through the PCB), in accordance with embodiments of the present invention.

Fig. 3E is a front view of the printed circuit board of the feed stalk of fig. 3B showing a pair of plated through holes in accordance with an embodiment of the present invention.

Fig. 3F is a perspective view of the feed stalk of fig. 3B, but assuming a transparent printed circuit board for illustration purposes, such that the current paths associated with the common mode band reject filter can be illustrated, in accordance with an embodiment of the present invention.

Fig. 4 is a top-down plan view of a box-shaped dipole antenna utilizing the four feed handles of fig. 3B-3F, in accordance with an embodiment of the present invention.

Detailed Description

The present invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between … …" versus "directly between … …", "adjacent" versus "directly adjacent", etc.).

Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical," may be used herein to describe one element, layer or region's relationship to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.

The aspects and elements of all embodiments disclosed herein below may be combined in any manner and/or with aspects or elements of other embodiments to provide multiple additional embodiments.

Referring now to fig. 3A, an antenna 30 in accordance with an embodiment of the present invention is illustrated as including a shared single-sided radiator segment 34a and a shared three-sided radiator segment 34b that extend along four sides of a rectangular (e.g., square) loop 34. As shown, the rectangular loop 34 is supported in front of a reflector surface 36 (e.g., ground plane) by a pair of "dual path" feed handles 32_1, 32_ 2. These feed stubs 32_1, 32_2 are each electrically coupled to a respective end of the radiator segments 34a, 34b so that the rectangular loop 34 can operate as a cross-polarized loop antenna. For example, when operating as an RF transmitter, rectangular loop 34 is responsive to first and second "outbound" Radio Frequency (RF) signals that are provided to first FEED port FEED1 and second FEED port FEED2 at the base of FEED handles 32_1, 32_ 2. Alternatively, when operating as a receiver of RF signals, rectangular loop 34 receives and delivers relatively low energy RF signals to FEED handles 32_1, 32_2, which are electrically coupled to low noise amplification and receiver circuitry (not shown) at first and second FEED ports fed 1, 2. In some embodiments of the present invention, rectangular loop 34 may be a relatively small square loop, each side spanning about 1/4 wavelengths of the operating frequency of the antenna.

Referring now to fig. 3B-3F, each feed stalk 32_1, 32_2 used by the loop antenna of fig. 3A may be configured as the same multilayer Printed Circuit Board (PCB) feed stalk 32. However, in alternative embodiments of the invention, feed stubs having different impedances may be advantageous (e.g., for isolation or pattern adjustment purposes) to support unbalanced polarization. In particular, and as shown in fig. 3B, the feed stalk 32 may include a dielectric (i.e., non-conductive) board substrate 42 having patterned metallization on first and second opposing faces thereof. On the first face, a first conductive path 38a is provided that includes a continuous metallization path that extends from one corner at a first "distal" end of the substrate 42 to a diametrically opposed corner on a second end (e.g., base) of the substrate 42, as shown. In addition, a second conductive path is defined by the patterned metal segments 38b, 38b ', and 38c and a pair of conductive (e.g., plated) vias 44a, 44b that electrically connect the "middle" segment 38c to the respective segments 38b and 38 b'.

As more fully shown by fig. 3C-3E, the first side 32' of the feed stalk 32 includes a serpentine shaped inductor 40a that extends in series within the first conductive path 38a (without interruption) and at a location intermediate the ends of the substrate 42, as shown. In addition, the patterned metal segments 38b, 38b 'on the first side 32' of the feed stalk 32, the two plated through holes 44a, 44b and the patterned metal segment 38c on the second side 32 "of the feed stalk 32 including the serpentine shaped inductor 40b collectively define a second conductive path extending between diametrically opposite corners of the feed stalk 32, as shown. According to an alternative embodiment of the invention, the first and second conductive paths (including the inductors 40a, 40b) may be provided in the absence of the dielectric plate substrate.

As will now be described more fully with reference to FIGS. 3B and 3F, the first and second serpentine inductors 40a, 40B extend on opposite first and second sides of the printed circuit board substrate 42, collectively defining a common mode band-stop (CMR) filter 40 that selectively and advantageously blocks common mode currents I, I_CMFrom a feed port at the base of the feed stalk 32 to a radiator segment 34a, 34b within the rectangular loop 34, which is mounted to the distal end of the feed stalk 32 and is electrically connected to a first conductive path 38a at the distal end and a respective one of the patterned metal segments 38 b. For example, with respect to the first FEED port (fed 1) shown in fig. 3A, CMR filter 40 blocks common mode current I_CMIs transferred to the distal portion of the first feed path 38a that is directly connected to the three-sided radiator segment 34b and blocks the common mode current I_CMTo a distal portion of the second feed path 38b that is directly connected to the single-sided radiator segment 34 a. Also, with respect to the second FEED port (fed 2), CMR filter 40 blocks common mode current I_CMIs transferred to the distal portion of the first feed path 38a that is directly connected to the single-sided radiator segment 34a and blocks the common mode current I_CMTo the distal portion of the second feed path 38b which is directly connected to the three sided radiator segment 34 b.

These preferential RF "blocking" characteristics of the CMR filter 40 are best understood by considering the way that the specific mutual inductance M between the overlapping serpentine-shaped inductors 40a, 40b separated by the PCB substrate 42 of predetermined thickness can be designed to block common mode currents at a first RF frequency but selectively pass (with very low attenuation) differential mode currents at the same RF frequency.

While not wishing to be bound by any theory, the first inductor 40a on the first side 32' of the substrate 42 may be considered to have an impedance Z₁Second inductor 40b on second side 32 "of substrate 42 may be considered to have an impedance Z₂Wherein:

Z₁＝R₁+jωL₁+jωM(I₂/I₁) (ii) a And

Z₂＝R₂+jωL₂+jωM(I₁/I₂)。

in these equations, R₁And R₂The resistances of the first inductor 40a and the second inductor 40b, respectively; l is₁And L₂The inductances of the first inductor 40a and the second inductor 40b, respectively; m is the mutual inductance between the overlapping first inductor 40a and second inductor 40b separated from each other by an electrically insulating PCB substrate 42; i is₁And I₂First and second currents into first and second ports (1, 2) of filter 40, respectively; ω is the angular frequency of the first and second currents. As shown by FIG. 3F, a first differential mode current I1_DMPassing from the distal portion of the first feed path 38a to the base of the first feed path 38a at the feed port, the first differential mode current is considered herein to be equal to I₁And from the base portion (metal segment 38 b') of the second feed path (at the feed port) to the I2 of the distal portion (metal segment 38b) of the second feed path (at the feed port)_DMConsidered herein to be equal to-I₂。

By careful design/adjustment of the inductor L₁And L₂(and its coupling) to be equal to each other and to the mutual inductance M between them (i.e.,L₁≈L₂m, where the sign "≈" indicates equality within ± 10%), and with respect to the differential-mode current I1 shown in fig. 3F_DMAnd I2_DMLet I assume₂＝-I₁Then the impedance of the first inductor 40a and the second inductor 40b may be considered equal to:

Z₁＝R₁+jω(L₁–M)≈R₁(ii) a And is

Z₂＝R₂+jω(L₂–M)≈R₂。

Thus, due to Z₁≈R₁And Z₂≈R₂The common mode band reject filter 40 presents a low resistive impedance to differential mode current, and this low impedance is equal to the inductor L₁And L₂The DC resistance of (1). However, with respect to the common mode current I shown in FIG. 3F_CMLet I assume₂＝I₁Then the impedance of the first inductor 40a and the second inductor 40b presents a high (and frequency dependent) inductive impedance in common mode, blocking common mode current, where:

Z₁＝R₁+jω(L₁+M)≈R₁+ j ω × 2L; and is

Z₂＝R₂+jω(L₂+M)≈R₂+jω×2L。

Thus, the lug-type common mode band reject filter 40 may be advantageously used to block common mode currents from passing through the feed lugs 32_1, 32_2, thereby suppressing single-pole type radiation from the loop radiator 34 of fig. 3A that might otherwise be present on these feed lugs.

According to further embodiments of the present invention, the feed stalk 32 and common mode band-stop filter 40 described above may be applied to many other antenna designs that may benefit from monopole-type radiation rejection caused by the generation of common mode currents within the radiating elements. For example, as shown by fig. 4, a box-shaped dipole antenna 50 (e.g., a sheet metal box-shaped dipole antenna) may be provided having four "shared" dipole radiating elements 52a-52d that collectively form four dipole radiators. The first dipole radiator is defined by radiating elements 52a, 52B that are electrically coupled to the first feed stalk 32_1 and a first feed port coupled to the base of the first feed stalk 32_1, as shown by fig. 3B-3F. Similarly, a second dipole radiator is defined by radiating elements 52b, 52c, which are electrically coupled to the second feed stalk 32_2 and the second feed port. The third dipole radiator is defined by radiating elements 52c, 52d that are electrically coupled to the third feed stalk 32_3 and the third feed port. Finally, a fourth dipole radiator is defined by radiating elements 52d, 52a, which are electrically coupled to the fourth feed stalk 32_4 and the fourth feed port. As described above with respect to the "loop" antenna 30 of fig. 3A-3F, the first through fourth feed handles 32_1 through 32_4 will enable differential mode operation on each excited port of the box-shaped dipole antenna 50, but effectively block common mode currents (and corresponding monopole radiation) on the ports associated with the opposite polarization relative to each excited port. Also, the feed stalk described above may be applied to rectangular box-shaped dipole antennas, as well as antennas having dipole radiating elements with unequal lengths and/or spacings therebetween, according to other embodiments of the present invention. In addition, the feed stalk and inductively coupled feed path described herein may be advantageously used in many antenna designs where differential mode signals are desired and common mode signals are not desired, such as, but not limited to, dipole type antennas.

In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.