CN114824742A - Dual polarized radiating element for a base station antenna with a built-in stalk filter blocking common mode radiation parasitics - Google Patents

Dual polarized radiating element for a base station antenna with a built-in stalk filter blocking common mode radiation parasitics Download PDF

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Publication number
CN114824742A
CN114824742A CN202210078520.9A CN202210078520A CN114824742A CN 114824742 A CN114824742 A CN 114824742A CN 202210078520 A CN202210078520 A CN 202210078520A CN 114824742 A CN114824742 A CN 114824742A
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China
Prior art keywords
feed
inductor
common
printed circuit
circuit board
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Chinese (zh)
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M·V·瓦奴斯法德拉尼
P·J·必思鲁勒斯
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Commscope Technologies LLC
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Commscope Technologies LLC
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Priority claimed from US17/552,390 external-priority patent/US12021315B2/en
Application filed by Commscope Technologies LLC filed Critical Commscope Technologies LLC
Publication of CN114824742A publication Critical patent/CN114824742A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/246—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for base stations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/50—Structural association of antennas with earthing switches, lead-in devices or lightning protectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/52—Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q7/00—Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

The present disclosure relates to dual polarized radiating elements for base station antennas with built-in stalk filters that block common mode radiation parasitics. The antenna includes a radiator electrically coupled to a feed stalk having a common mode band-stop (CMR) filter therein. The CMR filter is configured to suppress common mode radiation from a radiator by providing a frequency-dependent impedance to a pair of common mode currents within the feed stalk sufficient to increase a return loss associated with the pair of common mode currents to a level greater than-6 dB over a frequency range including the frequency of the common mode radiation.

Description

Dual polarized radiating element for a base station antenna with a built-in stalk filter blocking common mode radiation parasitics
Reference to priority application
This application claims priority to U.S. provisional patent application No. 63/140,742 filed on 22/1/2021 and U.S. patent application No. 17/552,390 filed on 16/12/2021.
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.
A conventional multi-band base station antenna design includes: at least one linear array of relatively "low band" radiating elements which may be used to provide service in some or all of the 617-960MHz frequency band; and at least two linear arrays of opposing "high band" radiating elements for providing service in some or all of the 1695-2690MHz bands.
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, an antenna radiating element is provided with a first radiator arm and a second radiator arm, which may be supported by a feed stalk in front of a 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 Z 1 A second impedance electrically coupled to the second port 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 )；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first and second inductors; i is 1 And I 2 A 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 Z 1 And Z 2 Is configured as I 1 Is equal to I 2 While blocking common-mode signals having a high frequency-dependent reactance, but when I 1 Is equal to-I 2 Selectively and efficiently passes differential mode signals having 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 equal to Z 1 Wherein 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 )；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A 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) is electrically coupled to a first end of the first dipole arm and a first end of the second dipole arm, and (ii) supports the first dipole radiator in front of a substrate (e.g., a ground plane reflector of a base station antenna).
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.
An antenna according to another embodiment of the invention includes a radiator, and a feed stalk having a common mode band-stop (CMR) filter embedded therein. In some of these embodiments, the radiator comprises first and second radiating arms (e.g., dipole arms) electrically coupled to respective first and second ports of the common-mode band-stop filter. This common-mode band-stop filter located in the feed signal path of the antenna is configured such that a first impedance therein is equal to Z 1 And wherein the second impedance is equal to Z 2 . The first impedance is electrically coupled to the first port and the second impedance is electrically coupled to the second port. According to these examples: z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 )；Z 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 )；L 1 ≈L 2 ；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the first inductor and the second inductorMutual inductance between devices; i is 1 And I 2 A first common mode current and a second common mode current flowing into the first port and the second port, respectively; the symbol "≈" designates equality within ± 10%; ω is the angular frequency of the first and second common mode currents; and M is close enough in magnitude to L 1 And L 2 Such that the return loss associated with the first and second common mode currents is greater than-6 dB at the angular frequency ω.
According to some of these embodiments of the invention, the feed signal path comprises a double-sided Printed Circuit Board (PCB) having hook-shaped feed lines on a first surface thereof. The first inductor and the second inductor may also be patterned as spiral inductors on the second surface of the PCB. Also, the spiral inductors may be configured as mirror images of each other about a centerline of the PCB that the hook-shaped feed line may traverse. In some embodiments, the PCB includes a first plated through hole electrically connecting the first end of the first inductor to a first metallization pattern on the first surface of the PCB and a second plated through hole electrically connecting the first end of the second inductor to a second metallization pattern on the first surface of the PCB. Based on this configuration of the PCB, the first radiating arm of the radiator may be electrically coupled to the first port of the common mode band-stop filter by the first metallization pattern, and the second radiating arm of the radiator may be electrically coupled to the second port of the common mode band-stop filter by the second metallization pattern. In addition, the second end of the first inductor may be electrically connected to a third metallization pattern covering a majority of the first half of the second surface of the PCB, and the second end of the second inductor may be electrically connected to a fourth metallization pattern covering a majority of the second half of the second surface of the PCB.
In still further embodiments of the present invention, an antenna is provided that includes a radiator having a first radiating arm and a second radiating arm, and a feed stalk having a common mode band-stop (CMR) filter therein. The CMR filter is configured such that a first impedance is electrically coupled to the first radiating armIs equal to Z 1 Wherein a second impedance electrically coupled to the second radiating arm is equal to Z 2 . According to this embodiment, Z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 ) And Z is 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 ) Wherein: r 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; and L is 1 ≈L 2 (ii) a M is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A first common mode current and a second common mode current in the first impedance and the second impedance, respectively; ω is the angular frequency of the first and second common mode currents; and the symbol "≈" designates equality within ± 25%.
In these embodiments, the first and second inductors may be spiral inductors configured as mirror images of each other about a centerline of the feed stalk. In addition, a first end of the first inductor is electrically connected to a first plated through hole in the feed stalk that extends between the first end of the first inductor and the first radiating arm, and a first end of the second inductor is electrically connected to a second plated through hole in the feed stalk that extends between the first end of the second inductor and the second radiating arm. The feed stalk may also be configured as a double-sided printed circuit board having a hook-shaped feed line on a first surface thereof. The first inductor and the second inductor may also be patterned as spiral inductors on a second surface of the printed circuit board. Preferably, the mutual inductance M is sufficiently close in magnitude to L1 and L2 such that the return loss associated with the first and second common-mode currents is greater than-6 dB at the angular frequency ω.
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.
Fig. 5A is a plan view of a multi-band antenna, including: (i) first and second outermost columns of first cross-polarized dipole radiating elements configured to operate in a first frequency band, (ii) first and second innermost columns of second cross-polarized dipole radiating elements configured to operate in a second frequency band, and (iii) first and second intermediate columns of third cross-polarized dipole radiating elements configured to operate in a third frequency band, the third frequency band being lower than the first and second frequency bands.
Fig. 5B is a plan view of a single-band antenna including first and second intermediate columns of third cross-polarized dipole radiating elements of fig. 5A.
Fig. 5C is a side view of one of the second cross-polarized dipole radiating elements of fig. 5A.
Figure 6A is a plot of the-10 dB beamwidth (in the azimuth plane) of the third cross-polarized dipole radiating element of figure 5A.
Figure 6B is a plot of the-10 dB beamwidth (in the azimuth plane) of the third cross-polarized dipole radiating element of figure 5B.
Fig. 7A is a side view of a cross-polarized dipole radiating element having first and second common-mode band-stop filters embedded within respective first and second feed handles (+45 °, -45 °) according to an embodiment of the invention.
Fig. 7B includes front and back side views of a first feed stalk within the radiating element of fig. 7A, according to an embodiment of the present invention.
Fig. 7C includes front and back side views of a first feed stalk within the radiating element of fig. 7A, according to an embodiment of the present invention.
Figure 8 is a plot of the-10 dB beamwidth (in the azimuth plane) of the third cross-polarized dipole radiating element of figure 5A modified by replacing the second cross-polarized dipole radiator of figure 5C with the cross-polarized dipole radiating element of figures 7A-7C.
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," and/or "having," when used in this specification, 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 CM From 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 CM Is 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 CM To 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 CM To a first feed path directly connected to the single-sided radiator segment 34a38a and blocks common mode current I CM To 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 Z 1 Second inductor 40b on second side 32 "of substrate 42 may be considered to have an impedance Z 2 Wherein:
Z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 ) (ii) a And
Z 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 )。
in these equations, R 1 And R 2 The resistances of the first inductor 40a and the second inductor 40b, respectively; l is a radical of an alcohol 1 And L 2 The 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 is 1 And I 2 First 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 DM Passing 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 I 1 And 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) DM Considered herein to be equal to-I 2 。
By careful design/adjustment of the inductor L 1 And L 2 (and coupling thereof) To be equal to each other and to the mutual inductance M (i.e., L) therebetween 1 ≈L 2 M, where the sign "≈" indicates equality within ± 10%), and with respect to the differential-mode current I1 shown in fig. 3F DM And I2 DM Let I assume 2 ＝-I 1 Then the impedance of the first inductor 40a and the second inductor 40b may be considered equal to:
Z 1 ＝R 1 +jω(L 1 –M)≈R 1 (ii) a And is
Z 2 ＝R 2 +jω(L 2 –M)≈R 2 。
Thus, due to Z 1 ≈R 1 And Z 2 ≈R 2 The common mode rejection filter 40 presents a low resistive impedance to differential mode currents, and this low impedance is equal to the inductor L 1 And L 2 The DC resistance of (1). However, with respect to the common mode current I shown in FIG. 3F CM Let I assume 2 ＝I 1 Then 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:
Z 1 ＝R 1 +jω(L 1 +M)≈R 1 + j ω × 2L; and is
Z 2 ＝R 2 +jω(L 2 +M)≈R 2 +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.
Referring now to fig. 5A, multi-band base station antenna 100a is shown to include six (6) columns of radiating elements mounted on the forward-facing surface of ground plane reflector 102. The six columns include: (i) two innermost columns of radiating elements 104, which may be configured to operate in a relatively high first frequency band (e.g., 1695-; (ii) two outermost columns of radiating elements 106, which may be configured to operate in a relatively high second frequency band (e.g., 1427-2690 MHz); and (iii) two intermediate columns of larger radiating elements 108, which may be configured to operate in a lower third frequency band (e.g., 696-.
As shown in the plan view of fig. 5A, each of the three types of radiating elements 104, 106, and 108 is configured as a corresponding dipole radiating element having two pairs of cross-polarized (e.g., -45 °, +45 °) radiating arms supported in front of the reflector 102 by a respective pair of feed handles. Furthermore, to achieve a high degree of integration within the base station antenna 100a, the smaller, relatively high- band radiating elements 104, 106 utilize shorter feed stubs, which allow nesting of these elements 104, 106 between the reflector 102 and the rearward surface of the larger radiating arm associated with the middle column of radiating elements 108.
Unfortunately, this nesting of the relatively high-band (HB) radiating elements 104, 106 in close proximity to the relatively low-band (LB) radiating element 108 may result in unacceptable interference between the HB and LB elements resulting from "induced" common mode resonances within the HB elements that are indirectly derived from differential mode radiation of the LB elements in response to a feed signal provided to the LB elements. While not wishing to be bound by any theory, the HB element is typically shorter than the LB element, and its height may be equal to 1/4 λ of the frequency within the high end of the frequency band of the LB element. As will be appreciated by those skilled in the art, such "common mode" interference can result in a large unacceptable increase in the beamwidth of the LB elements, as well as a degradation in gain and front-to-back ratio. Furthermore, using conventional common-mode filter techniques within the HB elements generally does not preclude the need to achieve a proper tradeoff between matching within the HB elements and pushing any common-mode resonances out of the frequency range of the LB elements.
One example of a conventional HB element 104 that may be configured to operate in a relatively high first frequency band is illustrated by fig. 5C. As shown, a pair of orthogonally interconnected first and second feed handles 110a, 110b are provided, which are electrically coupled to a corresponding pair of radiating arms. In fig. 5C, first feed stalk 110a is shown mechanically supporting first pair of radiating arms 112a, 112b in front of reflector 102. The first feed stalk 110a includes, among other things: a first hook-shaped feed line 114a that receives a corresponding cross-polarized feed signal; and a pair of serpentine inductors L1, L2 of the common mode filter extending adjacent the outermost side of the feed stalk 110 a. Where the first feed stalk 110a is configured as a double-sided Printed Circuit Board (PCB), the feed line 114a and inductors L1, L2 may be patterned on opposing "front" and "back" surfaces of the PCB, along with other metallization (and metallized vias) to achieve proper matching.
Despite the configuration of HB element 104 of fig. 5A and 5C, a relatively large increase in the beamwidth of LB element 108 within multi-band antenna 100a may still occur when all radiating elements 104, 106, and 108 are simultaneously active in their respective frequency bands. For example, as shown in fig. 6A, the-10 dB beamwidth (in the azimuth plane) plot of the third cross-polarized dipole radiating element 108 of fig. 5A exhibits a sharp and unacceptable broadening of the beamwidth at relatively high frequencies, particularly at frequencies above 950 MHz. However, when the LB element 108 is operated alone (i.e., without the HB elements 104, 106), there is no such broadening, as shown by the dedicated LB antenna 100B of fig. 5B and fig. 6B and the corresponding-10 dB beamwidth diagram.
To address this limitation associated with the HB element 104 of fig. 5C, a cross-polarized dipole radiating element 204 is provided that includes first and second feed shanks (+45o, -45o) having highly mutually coupled first and second common mode band-stop filters embedded therein. As shown in the embodiment of fig. 7A-7C, this HB radiating element 204 includes a pair of orthogonally interconnected first and second Feed handles 210a, 210b mounted on the ground plane reflector 102 and receiving respective Feed signals (Feed1, Feed2) therethrough. These first and second feed handles 210a, 210b are also collectively configured to mechanically support first and second pairs of dipole radiating arms thereon. As shown in the side view of fig. 7A, the first feed handle 210a is electrically coupled to the respective first and second radiating arms 112a, 112b at first and second ports (Port1, Port 2).
This first feed stalk 210a is shown in more detail by fig. 7B, which shows a front view and a back view of a double-sided printed circuit board 212a having a metallization pattern thereon. Specifically, the first hook-shaped feed line 214a is provided on the front side of the board 212 a. The first Feed line 214a is configured to receive a corresponding first Feed signal (Feed1) at the base of the first board 212a, which when installed extends through the ground planeA surface reflector 102. The first feed line 214a also extends across the centerline (C/L) of the first plate 212a and is proximate to the terminal end of the main notch/slot 216a, as shown. The first feed stalk 210a also includes a pair of closely spaced equivalent spiral inductors L1, L2 on the rear side of the plate 212 a. Advantageously, these spiral inductors L1, L2 are configured to have a high degree of mutual inductive coupling (M) therebetween, which helps to suppress common mode currents (I1) within the first feed stalk 210a CM ，I2 CM ) A common mode current is induced in the first feed stalk in response to radiation received by the radiating element 204.
In particular, according to some embodiments of the present invention, the shape and close spacing of the "mirrored" spiral inductors L1 and L2 is sufficient to produce a relatively high mutual inductance M, such that the first common mode current I1 that is suppressed is coupled with CM And a second common mode current I2 CM The associated return loss is greater than-6 dB at an angular frequency ω corresponding to frequencies within a portion of the low frequency band that is generally outside the relatively high frequency band associated with the HB radiating element 204.
In addition, each of the counterclockwise spiral inductor L1 and the clockwise spiral inductor L2 terminates at a respective plated through hole 218 that provides a conductive path to the first and second ports Port1, Port2 and radiating arms 112a, 112b of the first feed stalk 210 a. As shown, these conductive paths include a substantially equal metallization pattern 222 on the front side of the plate 212a that supports a relative differential mode current I1 in the high frequency band during operation DM 、I2 DM . The back side of plate 212a also includes a large area metal pattern 224 that supports differential mode current I1 across feed stalk 210a DM 、I2 DM . Each of these metal patterns 224 covers most of the half of the rear side of the plate 212 and is electrically coupled to a corresponding metal pattern 226 on the front side of the plate 212a by a plurality of plated through holes PTH.
While not wishing to be bound by any theory, the illustrated overlap between the metal pattern 222 on the front side of the plate 212 and the larger metal pattern 224 on the back side provides coupling within the built-in impedance matching circuit provided by the first feed stalk 210 a. In addition, the relatively large number of plated through holes PTH supports the creation of a grounded coplanar waveguide structure, which can improve: (i) isolation between the two polarizations, (ii) cross-polarized radiation in the far field, and (iii) insertion loss.
Referring now to fig. 7C, the second feed stalk 210b is similarly shown to include a printed circuit board 212b having a second hook-shaped feed line 214b on a front side thereof. The second feedline 214b is configured to receive a corresponding second feedline signal (Feed2) at the base of the second plate 212b, the second feedline extending through the ground plane reflector 102. The second feed line 214b also extends adjacent a terminal end of a second notch/slot 216b that mates in an orthogonal relationship with the primary notch/slot 216a when assembled. The second feed stalk 210b includes a pair of closely spaced spiral inductors L1 and L2 on the rear side of the plate 212 b. As described above with reference to FIG. 7B, these spiral inductors L1 and L2 are configured to have a high degree of mutual inductive coupling (M) therebetween, which helps to suppress common-mode currents (I1) that are "induced" within the second feed stalk 210B in response to low-band radiation from adjacent radiating elements, such as the LB element 108 of FIGS. 5A-5B CM 、I2 CM )。
As shown, each of the spiral inductors L1 and L2 terminates at a respective plated through hole 218 that provides a conductive path to the first Port1 and the second Port2 of the second feed stalk 210 b. These conductive paths include substantially equal metallization patterns 222 on the front side of plate 212b that support opposing differential mode currents I1 during operation DM 、I2 DM . The back side of the plate 212b also includes a large area metal pattern 224 that supports the differential mode current I1 on the feed stalk 210b DM 、I2 DM . Each of these metal patterns 224 is electrically coupled to a corresponding metal pattern 226 on the front side of the board 212b by a plurality of plated through holes PTH.
Referring now to fig. 8, a plot of the-10 dB beamwidth (in the azimuth plane) of the third cross-dipole radiating element of fig. 5A is provided, which illustrates that a substantial improvement in Common Mode (CM) interference can be achieved by replacing the second cross-dipole radiating element 104 of fig. 5C with the HB cross-dipole radiating element 204 of fig. 7A-7C. While not wishing to be bound by any theory, the responseThe shape and close spacing of the "mirror" spiral inductors L1 and L2 in fig. 7A-7C, which produce a relatively high mutual inductance M between L1 and L2, achieves a high degree of suppression of CM interference. According to some embodiments of the invention, this mutual inductance is high enough to be compatible with the suppressed common-mode current (see, e.g., I1 in FIGS. 7B-7B) CM 、I2 CM ) The associated return loss is greater than-6 dB at an angular frequency of operation, ω, which may correspond to frequencies within a portion of the low frequency band generally outside of the relatively high frequency band associated with the HB radiating element 204.
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.
The present invention also includes the following examples.
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 example 1, wherein the common mode band reject filter includes a pair of mutually coupled inductors therein.
3. The antenna of example 2, wherein the pair of mutually coupled inductors are positioned intermediate the base and distal ends of the feed stalk.
4. The antenna of example 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 of example 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 sides of the printed circuit board.
6. The antenna of example 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 example 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 example 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 sides of the printed circuit board.
9. The antenna of example 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 example 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 example 4, wherein the common-mode band-stop 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 )；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first and second inductors; i is 1 And I 2 A 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 example 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-stop filter.
13. The antenna of example 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 example 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 example 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-stop filter.
16. The antenna of example 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 example 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 Z 1 And wherein 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 )；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A 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 example 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 of example 18, further comprising first to fourth feed handles electrically coupled to first to fourth corners of the box-shaped dipole antenna, the first to fourth feed handles including respective first to fourth common-mode band-stop filters integrated therein.
21. The antenna of example 20, wherein the first to fourth common-mode band-stop filters have the same impedance characteristics.
22. The antenna of example 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 example 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 example 24, wherein the common mode band reject filter includes a pair of mutually coupled inductors therein.
26. The antenna of example 25, wherein the pair of mutually coupled inductors are disposed intermediate a top and a bottom of the feed stalk.
27. The antenna of example 25, wherein the pair of mutually coupled inductors comprise: 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 of example 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 sides of the printed circuit board.
29. The antenna of example 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 example 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 of example 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 sides of the printed circuit board.
32. The antenna of example 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 example 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 example 27, wherein the common-mode band-stop 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 )；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first and second inductors; i is 1 And I 2 A 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 current and the second current.
35. The antenna of any of examples 24-34, wherein the radiator is selected from a box dipole radiator and a loop radiator.
36. An antenna, comprising:
a radiator electrically coupled to respective first and second ports of a common-mode band-stop filter disposed 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 Z 1 And wherein a second impedance electrically coupled to the second port is equal to Z 2 Wherein: z is a linear or branched member 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 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 Respectively said first inductor and saidAn inductance of the second inductor; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A 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 of example 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 of example 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 of example 36, wherein the common-mode band-stop filter is integrated into a feed stalk 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 of any of examples 36-39, 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 example 41, wherein the first inductor and the 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 example 43, wherein the common-mode band-stop 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 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A 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.
45. A radiating element, comprising:
a cross dipole radiator; and
first and second feed handles electrically coupled to the cross-dipole radiator and responsive to respective first and second Radio Frequency (RF) feed signals, the first and second feed handles including respective first and second common-mode band-stop (CMR) filters thereinA rejection filter, the first CMR filter including a first impedance Z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 ) And a second impedance Z 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 ) Wherein L is 1 And L 2 Is the inductance of the respective first and second inductors within the first feed stalk; l is 1 ≈L 2 Where the symbol "≈" designates equality within ± 20%; r 1 And R 2 Is the resistance 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 common mode current and a second common mode current in the first feed stalk; ω is the angular frequency of the first and second common mode currents; and M is close enough in magnitude to L 1 And L 2 Such that a return loss associated with the first and second common-mode currents is greater than-6 dB at the angular frequency ω.
46. The radiating element of example 45, wherein the first feed stalk comprises a double-sided printed circuit board having an L on a first surface of the double-sided printed circuit board 1 And L 2 And has a feed trace with a U-shaped feed section on a second surface of the printed circuit board.
47. The radiating element of example 45, wherein the first feed stalk comprises a first double-sided printed circuit board having an L of on a first surface of the first double-sided printed circuit board 1 And L 2 And having a feed trace with a U-shaped feed section on a second surface of the first double-sided printed circuit board; and wherein the second feed stalk comprises a second double-sided printed circuit board having a pair of side-by-side inductors on a first surface of the second double-sided printed circuit board and a feed trace with a U-shaped feed section on a second surface of the second double-sided printed circuit board.
48. The radiating element of example 45, wherein the first and second feed stubs include respective first and second double-sided printed circuit boards having complementary grooves therein that interlock with one another.
49. The radiating element of example 45, wherein the first inductor L 1 And the second inductor L 2 Configured as a first spiral inductor and a second spiral inductor, respectively.
50. The radiating element of example 49, wherein the first handle comprises a double-sided Printed Circuit Board (PCB); wherein the first spiral inductor and the second spiral inductor are patterned on a first surface of the PCB; and wherein the first spiral inductor spirals inward in a counterclockwise direction and the second spiral inductor spirals inward in a clockwise direction.
51. The radiating element of example 46, wherein L 1 And L 2 Is a spiral inductor.
52. The radiating element of example 51, wherein L 1 And L 2 Patterned as mirror images of each other with respect to a central axis of the printed circuit board.
53. The radiating element of example 52, wherein the first and second feed stubs include respective first and second double-sided printed circuit boards having complementary grooves therein that interlock with each other along the central axis.
54. A radiating element, comprising:
a radiator electrically coupled to a first port and a second port of a common-mode band-stop filter disposed in a feed signal path of the radiating element, the common-mode band-stop filter configured such that a first impedance therein electrically coupled to the first port is equal to Z 1 And wherein 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 )；L 1 ≈L 2 ；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A first common mode current and a second common mode current flowing into the first port and the second port, respectively; the symbol "≈" indicates equality within ± 10%; ω is the angular frequency of the first and second common mode currents; and M is close enough in magnitude to L 1 And L 2 Such that a return loss associated with the first and second common-mode currents is greater than-6 dB at an angular frequency ω.
55. The radiating element of example 54, wherein the feed signal path comprises a double-sided Printed Circuit Board (PCB) having a hook-shaped feed line on a first surface of the double-sided PCB.
56. The radiating element of example 54, wherein the first inductor and the second inductor are patterned on a second surface of the PCB.
57. The radiating element of example 56, wherein the first inductor and the second inductor are spiral inductors.
58. The radiating element of example 57, wherein the first inductor and the second inductor are configured as mirror images of each other about a centerline of the PCB traversed by the hook feed line.
59. The radiating element of example 58, wherein the PCB comprises a first plated through hole electrically connecting a first end of the first inductor to a first metallization pattern on a first surface of the PCB; and wherein the PCB includes a second plated through hole electrically connecting the first end of the second inductor to a second metallization pattern on the first surface of the PCB.
60. The radiating element of example 59, wherein a first radiating arm of the radiator is electrically coupled to a first port of the common mode band-stop filter by the first metallization pattern; and wherein the second radiating arm of the radiator is electrically coupled to the second port of the common mode band reject filter by the second metallization pattern.
61. The radiating element of example 60, wherein a second end of the first inductor is electrically connected to a third metallization pattern that covers a majority of the first half of the second surface of the PCB; and wherein a second end of the second inductor is electrically connected to a fourth metallization pattern that covers a majority of the second half of the second surface of the PCB.
62. A radiating element, comprising:
a radiator having a first radiating arm and a second radiating arm; and
a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured such that a first impedance therein electrically coupled to the first radiating arm is equal to Z 1 And wherein a second impedance electrically coupled to the second radiating arm 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 )；L 1 ≈L 2 ；R 1 And R 2 Resistances of the first spiral inductor and the spiral second inductor, respectively; l is 1 And L 2 The inductances of the first spiral inductor and the second spiral inductor, respectively; m is the mutual inductance between the first spiral inductor and the second spiral inductor; i is 1 And I 2 A first and a second common mode current in the first and the second impedance, respectively; ω is the angular frequency of the first and second common mode currents; and the symbol "≈" designates equality within ± 25%.
63. The radiating element of example 62, wherein the first spiral inductor and the second spiral inductor are configured as mirror images of each other about a centerline of the feed stalk.
64. The radiating element of example 63, wherein a first end of the first spiral inductor is electrically connected to a first plated through hole within the feed stalk, the first plated through hole extending between the first end of the first spiral inductor and the first radiating arm; and wherein a first end of the second spiral inductor is electrically connected to a second plated through hole within the feed stalk, the second plated through hole extending between the first end of the second spiral inductor and the second radiating arm.
65. The radiating element of example 63, wherein the feed stalk is a double-sided printed circuit board having hook-shaped feed lines on a first surface of the double-sided printed circuit board; and wherein the first spiral inductor and the second spiral inductor are patterned on a second surface of the printed circuit board.
66. The radiating element of example 65, wherein M is sufficiently close in magnitude to L1 and L2 that a return loss associated with the first and second common-mode currents is greater than-6 dB at the angular frequency ω.
67. The radiating element of example 66, wherein a first end of the first spiral inductor is electrically connected to a first plated through hole within the feed stalk, the first plated through hole extending between the first end of the first spiral inductor and the first radiating arm; and wherein a first end of the second spiral inductor is electrically connected to a second plated through hole within the feed stalk, the second plated through hole extending between the first end of the second spiral inductor and the second radiating arm.
68. The radiating element of example 67, wherein a second end of the first spiral inductor is electrically connected to a metallization pattern covering a majority of a first half of a second surface of the PCB; and wherein a second end of the second spiral inductor is electrically connected to a metallization pattern covering a majority of the second half of the second surface of the PCB.
69. A radiating element, comprising:
a radiator having a first radiating arm and a second radiating arm; and
a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured such that a first impedance therein electrically coupled to the first radiating arm is equal to Z 1 And wherein a second impedance electrically coupled to the second radiating arm 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 )；L 1 ≈L 2 ；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A first and a second common mode current in the first and the second impedance, respectively; ω is the angular frequency of the first and second common mode currents; the symbol "≈" designates equality within ± 25%; and M is sufficiently close in magnitude to L1 and L2 such that a return loss associated with the first and second common mode currents is greater than-6 dB at an angular frequency ω.
70. The radiating element of example 69, wherein the feed stalk comprises a double-sided Printed Circuit Board (PCB) having a hook-shaped feed line on a first surface of the double-sided PCB; and wherein the first and second inductors are configured as first and second spiral inductors on a second surface of the PCB.
71. The radiating element of example 70, wherein the first inductor is electrically connected to the first radiating arm via a first metal trace on the first surface of the PCB and the second inductor is electrically connected to the second radiating arm via a second metal trace on the first surface of the PCB.
72. An antenna, comprising:
a radiator electrically coupled to a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured to suppress common-mode radiation from the radiator by providing a pair of common-mode currents within the feed stalk with a frequency-dependent impedance that is sufficient to increase a return loss associated with the pair of common-mode currents to a level greater than-6 dB over a frequency range that includes a frequency of the common-mode radiation.
73. The antenna of example 72, wherein the feed stalk is a double-sided Printed Circuit Board (PCB) having a feed line on a first surface of the double-sided printed circuit board; and wherein the CMR filter includes a pair of spiral inductors on the second surface of the PCB.
74. The antenna of example 72, wherein when the antenna is active and responsive to radiation by (i) at least a first RF feed signal at the frequency of the differential mode current and (ii) an adjacent radiator in response to at least a second RF feed signal at the frequency of the common mode radiation, the frequency of the common mode radiation is less than the frequency of the differential mode current within the CMR filter.
75. An antenna, comprising:
a reflector;
a first radiating element responsive to at least a first feed signal on the reflector;
a second radiating element responsive to at least a second feed signal on the reflector, the second radiating element comprising:
a radiator electrically coupled to a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured to suppress common-mode radiation from the radiator by providing a pair of common-mode currents within the feed stalk with a frequency-dependent impedance that is sufficient to increase a return loss associated with the pair of common-mode currents to a level greater than-6 dB over a frequency range that includes a frequency of the common-mode radiation.
76. The antenna of example 75, wherein the pair of common-mode currents are induced within the feed stalk in response to differential-mode radiation from the first radiating element.

Claims (17)

1. A radiating element, comprising:
a cross dipole radiator; and
first and second feed handles electrically coupled to the cross-dipole radiator and responsive to respective first and second Radio Frequency (RF) feed signals, the first and second feed handles including respective first and second common-mode band-stop (CMR) filters therein, the first CMR filter including a first impedance Z 1 ＝R 1 +jωL 1 +jωM(I 2 /I 1 ) And a second impedance Z 2 ＝R 2 +jωL 2 +jωM(I 1 /I 2 ) Wherein L is 1 And L 2 Is the inductance of the respective first and second inductors within the first feed stalk; l is 1 ≈L 2 Where the symbol "≈" designates equality within ± 20%; r 1 And R 2 Is the resistance 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 common mode current and a second common mode current in the first feed stalk; ω is the angular frequency of the first and second common mode currents; and M is close enough in magnitude to L 1 And L 2 Such that a return loss associated with the first and second common-mode currents is greater than-6 dB at the angular frequency ω.
2. The radiating element of claim 1, wherein the first feed stalk comprises a double-sided printed circuit board having an L on a first surface of the double-sided printed circuit board 1 And L 2 And has a feed trace with a U-shaped feed section on a second surface of the printed circuit board.
3. According toThe radiating element of claim 1, wherein the first feed stalk comprises a first double-sided printed circuit board having an L on a first surface of the first double-sided printed circuit board 1 And L 2 And having a feed trace with a U-shaped feed section on a second surface of the first double-sided printed circuit board; and wherein the second feed stalk comprises a second double-sided printed circuit board having a pair of side-by-side inductors on a first surface of the second double-sided printed circuit board and a feed trace with a U-shaped feed section on a second surface of the second double-sided printed circuit board.
4. The radiating element of claim 1, wherein the first and second feed stubs include respective first and second double-sided printed circuit boards having complementary grooves therein that interlock with one another.
5. The radiating element of claim 1, wherein the first inductor L 1 And the second inductor L 2 Configured as a first spiral inductor and a second spiral inductor, respectively.
6. The radiating element of claim 5, wherein the first handle comprises a double-sided Printed Circuit Board (PCB); wherein the first spiral inductor and the second spiral inductor are patterned on a first surface of the PCB; and wherein the first spiral inductor spirals inward in a counterclockwise direction and the second spiral inductor spirals inward in a clockwise direction.
7. The radiating element of claim 2, wherein L 1 And L 2 Is a spiral inductor.
8. The radiating element of claim 7, wherein L 1 And L 2 Patterned as mirror images of each other with respect to a central axis of the printed circuit board.
9. The radiating element of claim 8, wherein the first and second feed stubs include respective first and second double-sided printed circuit boards having complementary grooves therein that interlock with one another along the central axis.
10. A radiating element, comprising:
a radiator having a first radiating arm and a second radiating arm; and
a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured such that a first impedance therein electrically coupled to the first radiating arm is equal to Z 1 And wherein a second impedance electrically coupled to the second radiating arm 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 )；L 1 ≈L 2 ；R 1 And R 2 Resistances of the first inductor and the second inductor, respectively; l is 1 And L 2 The inductances of the first and second inductors, respectively; m is the mutual inductance between the first inductor and the second inductor; i is 1 And I 2 A first and a second common mode current in the first and the second impedance, respectively; ω is the angular frequency of the first and second common mode currents; the symbol "≈" designates equality within ± 25%; and M is sufficiently close in magnitude to L1 and L2 such that a return loss associated with the first and second common mode currents is greater than-6 dB at an angular frequency ω.
11. The radiating element of claim 10, wherein the feed stalk comprises a double-sided Printed Circuit Board (PCB) having a hook-shaped feed line on a first surface of the double-sided PCB; and wherein the first and second inductors are configured as first and second spiral inductors on a second surface of the PCB.
12. The radiating element of claim 11, wherein the first inductor is electrically connected to the first radiating arm via a first metal trace on the first surface of the PCB, and the second inductor is electrically connected to the second radiating arm via a second metal trace on the first surface of the PCB.
13. An antenna, comprising:
a radiator electrically coupled to a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured to suppress common-mode radiation from the radiator by providing a pair of common-mode currents within the feed stalk with a frequency-dependent impedance that is sufficient to increase a return loss associated with the pair of common-mode currents to a level greater than-6 dB over a frequency range that includes a frequency of the common-mode radiation.
14. The antenna of claim 13, wherein the feed stalk is a double-sided Printed Circuit Board (PCB) having a feed line on a first surface of the double-sided printed circuit board; and wherein the CMR filter includes a pair of spiral inductors on the second surface of the PCB.
15. The antenna of claim 13, wherein when the antenna is active and responsive to radiation by (i) at least a first RF feed signal at the frequency of the differential mode current, and (ii) an adjacent radiator in response to at least a second RF feed signal at the frequency of the common mode radiation, the frequency of the common mode radiation is less than the frequency of the differential mode current within the CMR filter.
16. An antenna, comprising:
a reflector;
a first radiating element responsive to at least a first feed signal on the reflector;
a second radiating element responsive to at least a second feed signal on the reflector, the second radiating element comprising:
a radiator electrically coupled to a feed stalk having a common-mode band-stop (CMR) filter therein, the CMR filter configured to suppress common-mode radiation from the radiator by providing a pair of common-mode currents within the feed stalk with a frequency-dependent impedance that is sufficient to increase a return loss associated with the pair of common-mode currents to a level greater than-6 dB over a frequency range that includes a frequency of the common-mode radiation.
17. The antenna of claim 16, wherein the pair of common mode currents are induced within the feed stalk in response to differential mode radiation from the first radiating element.
CN202210078520.9A 2021-01-22 2022-01-24 Dual polarized radiating element for a base station antenna with a built-in stalk filter blocking common mode radiation parasitics Pending CN114824742A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US202163140742P 2021-01-22 2021-01-22
US63/140,742 2021-01-22
US17/552,390 US12021315B2 (en) 2019-03-22 2021-12-16 Dual-polarized radiating elements for base station antennas having built-in common-mode rejection filters that block common mode radiation parasitics
US17/552,390 2021-12-16

Publications (1)

Publication Number Publication Date
CN114824742A true CN114824742A (en) 2022-07-29

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Country Link
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