Patent Grant
12051855
The present invention generally relates to radio communications and, more particularly, to base station antennas for cellular communications systems.
Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells” which are served by respective base stations. The base station may include one or more antennas that are configured to provide two-way radio frequency (“RF”) communications with mobile subscribers that are within the cell served by the base station. In many cases, each base station is divided into “sectors.” In one common configuration, a hexagonally shaped cell is divided into three 120° sectors in the azimuth plane, and each sector is served by one or more base station antennas that have an azimuth Half Power Beamwidth (“HPBW”) of approximately 65°. Typically, the base station antennas are mounted on a tower or other raised structure, with the radiation patterns (also referred to herein as “antenna beams”) that are generated by the base station antennas directed outwardly. Base station antennas are often implemented as linear or planar phased arrays of radiating elements.
In order to accommodate the increasing volume of cellular communications, cellular operators have added cellular service in a variety of new frequency bands. While in some cases it is possible to use a single array of so-called “wide-band” or “ultra wide-band” radiating elements to provide service in multiple frequency bands, in other cases it is necessary to use different arrays of radiating elements to support service in the different frequency bands.
As the number of frequency bands has proliferated, and increased sectorization has become more common (e.g., dividing a cell into six, nine or even twelve sectors), the number of base station antennas deployed at a typical base station has increased significantly. However, due to, for example, local zoning ordinances and/or weight and wind loading constraints for the antenna towers, there is often a limit as to the number of base station antennas that can be deployed at a given base station. In order to increase capacity without further increasing the number of base station antennas, so-called multi-band base station antennas have been introduced which include multiple arrays of radiating elements. Multi-band base station antennas are now being developed that include arrays that operate in three different frequencies bands. For example, base station antennas are now being deployed that include two linear arrays of “low-band” radiating elements that operate in some or all of the 694-960 MHz frequency band, two linear arrays of “mid-band” radiating elements that operate in some or all of the 1427-2690 MHz frequency band and one or more multi-column (planar) arrays of “high-band” radiating elements that operate in some or all of a higher frequency band, such as the 3.3-4.2 GHz frequency band. Unfortunately, the different arrays can interact with each other, which may make it challenging to implement such a multi-band antenna while also meeting customer requirements relating to the size (and particularly the width) of the base station antenna.
Pursuant to embodiments of the present invention, antennas (e.g., a base station antenna) are provided that comprise a reflector, a first radiating element extending forwardly from the reflector that is configured to operate in a first operating frequency band, and a second radiating element extending forwardly from the reflector that is configured to operate in a second operating frequency band that encompasses higher frequencies than the first operating frequency band. The first radiating element includes a first dipole radiator having a first dipole arm and a second dipole arm and a second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first conductive path and a second conductive path that is positioned behind the first conductive path. The first conductive path includes a plurality of first segments and the second conductive path includes a plurality of second segments, where a subset of the first segments overlap respective ones of the second segments in a subset of the second segments to form a plurality of pairs of overlapping first and second segments. At least some of the pairs of overlapping first and second segments are configured so that the instantaneous direction of a first current formed on the first segment in response to RF radiation emitted by the second radiating element will be substantially opposite the instantaneous direction of a second current formed on the second segment in response to the RF radiation emitted by the second radiating element.
In some embodiments, the first conductive path may be a first meandered conductive path and the second conductive path may be a second meandered conductive path.
In some embodiments, the first conductive path may be implemented in a first metal layer of a printed circuit board and the second conductive path may be implemented in a second metal layer of the printed circuit board.
In some embodiments, the first meandered conductive path may be a plurality of first longitudinal segments that generally extend parallel to a longitudinal direction of the first dipole arm and a plurality of first transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm. In some embodiments, the second meandered conductive path may be a plurality of second longitudinal segments that generally extend parallel to the longitudinal direction of the first dipole arm and a plurality of second transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm. In some embodiments, at least some of the pairs of overlapping first and second segments may be a respective one of the first transverse segments and a respective one of the second transverse segments. In some embodiments, substantially all of the first transverse segments may overlap a respective one of the second transverse segments.
In some embodiments, in at least some of the pairs of overlapping first and second segments, one of the first and second segments may completely overlap the other of the first and second segments.
In some embodiments, at least one of the first transverse segments may be wider than at least one of the first longitudinal segments.
In some embodiments, the first radiating element may further include a feed stalk having a feed line, and the first conductive path may be galvanically connected to the feed line and the second conductive path may be galvanically coupled to the feed stalk.
In some embodiments, the first conductive path and the second conductive path of each of the first through fourth dipole arms may form respective closed loops.
In some embodiments, the first meandered conductive path may be a wave structure having a first frequency, and the second meandered conductive path may be a wave structure having a second frequency that is different than the first frequency.
In some embodiments, the second dipole arm may include a third conductive path that is substantially identical to the first conductive path, and a fourth conductive path that is substantially identical to the second conductive path, and the first dipole arm may overlap the second radiating element.
In some embodiments, the antenna may further comprise a third radiating element extending forwardly from the reflector that is configured to operate in a third operating frequency band that encompasses higher frequencies than the second operating frequency band, where the second dipole arm overlaps the third radiating element. In some of these embodiments, the first and second dipole arms may be configured to be substantially transparent to RF signals in the second operating frequency band and in the third operating frequency band.
In some embodiments, the first radiating element may further comprise at least one feed stalk that extends generally perpendicular to the reflector, and each of the first through fourth dipole arms may include first and second spaced-apart conductive segments that together form a generally oval shape.
In some embodiments, an average length of the first transverse segments may be less than ¼ of a wavelength corresponding to a center frequency of the second operating frequency band.
In some embodiments, an average width of the first meandered conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second meandered conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
Pursuant to further embodiments of the present invention, radiating elements are provided that comprise a first dipole radiator having a first dipole arm and a second dipole arm and a second dipole radiator having a third dipole arm and a fourth dipole arm, where the first dipole arm includes a first meandered conductive path that extends from a base of the first dipole arm to a distal end of the first dipole arm and a second meandered conductive path that is positioned behind the first meandered conductive path.
In some embodiments, an average width of the first meandered conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second meandered conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
In some embodiments, the first meandered conductive path may be a plurality of first longitudinal segments that generally extend parallel to a longitudinal direction of the first dipole arm and a plurality of first transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm, and the second meandered conductive path may be a plurality of second longitudinal segments that generally extend parallel to the longitudinal direction of the first dipole arm and a plurality of second transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm.
In some embodiments, an average length of the first transverse segments may be less than ¼ of a wavelength corresponding to a center frequency of the second operating frequency band.
In some embodiments, at least some of the first transverse segments may overlap respective ones of the second transverse segments.
In some embodiments, substantially all of the first transverse segments may overlap a respective ones of the second transverse segments.
In some embodiments, at least some of the first transverse segments may completely overlap respective ones of the second transverse segments.
In some embodiments, at least one of the first transverse segments may be wider than at least one of the first longitudinal segments.
In some embodiments, the first radiating element further includes a feed stalk having a feed line, and the first meandered conductive path may be galvanically connected to the feed line and the second meandered conductive path may be galvanically coupled to the feed stalk.
In some embodiments, the first meandered conductive path and the second meandered conductive path may form respective closed loops.
In some embodiments, the first meandered conductive path may be a wave structure having a first frequency, and the second meandered conductive path may be a wave structure having a second frequency that is different than the first frequency.
In some embodiments, the first meandered conductive path may have a generally oval shape.
In some embodiments, the second meandered conductive path may have a generally oval shape.
In some embodiments, the first meandered conductive path may be a plurality of first wave sections that each have a wave structure, and a plurality of first transition sections that connect respective adjacent pairs of the first wave sections.
In some embodiments, the second meandered conductive path may be a plurality of second wave sections that each have a wave structure, and a plurality of second transition sections that connect respective adjacent pairs of the second wave sections.
Pursuant to still further embodiments of the present invention, antennas such as base station antennas are provided that comprise a reflector, a first radiating element extending forwardly from the reflector that is configured to operate in a first operating frequency band, the first radiating element including a first dipole arm, and a second radiating element extending forwardly from the reflector that is configured to operate in a second operating frequency band that encompasses higher frequencies than the first operating frequency band. The first dipole arm includes a first conductive path and a second conductive path that are spaced apart from each other. A first segment of the first conductive path overlaps a second segment of the second conductive path. The first dipole arm is configured so that first and second currents that are induced on the respective first and second conductive paths in response to radio frequency (“RF”) radiation emitted by the second radiating element each flow outwardly along the first dipole arm, but flow in substantially opposite directions along the respective first and second segments.
In some embodiments, the first radiating element may be a first dipole radiator that includes the first dipole arm and a second dipole arm, and a second dipole radiator having a third dipole arm and a fourth dipole arm, and each dipole arm includes a base that is adjacent a center of the first radiating element and a distal end that is positioned outwardly of the base.
In some embodiments, the first conductive path may be a first meandered conductive path and the second conductive path may be a second meandered conductive path.
In some embodiments, the first conductive path may be implemented in a first metal layer of a printed circuit board and the second conductive path may be implemented in a second metal layer of the printed circuit board.
In some embodiments, the first meandered conductive path may be a plurality of first longitudinal segments that generally extend parallel to a longitudinal direction of the first dipole arm and a plurality of first transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm, and the second meandered conductive path may be a plurality of second longitudinal segments that generally extend parallel to the longitudinal direction of the first dipole arm and a plurality of second transverse segments that generally extend perpendicular to the longitudinal direction of the first dipole arm.
In some embodiments, the first segment may be one of the first transverse segments, and the second segment may be one of the second transverse segments.
In some embodiments, an average length of the first transverse segments may be less than ¼ of a wavelength corresponding to a center frequency of the second operating frequency band.
In some embodiments, an average width of the first meandered conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second meandered conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
In some embodiments, the first meandered conductive path may be a wave structure having a first frequency, and the second meandered conductive path may be a wave structure having a second frequency that is different than the first frequency.
Pursuant to further embodiments of the present invention, antennas (e.g., a base station antenna) are provided that include a reflector, a first radiating element extending forwardly from the reflector that is configured to operate in a first operating frequency band, and a second radiating element extending forwardly from the reflector that is configured to operate in a second operating frequency band that encompasses higher frequencies than the first operating frequency band. These antennas also include one or more parasitic elements that each include a first conductive path and a second conductive path that is positioned behind the first conductive path. The first conductive path includes a plurality of first segments and the second conductive path includes a plurality of second segments. A subset of the first segments overlap respective ones of the second segments in a subset of the second segments to form a plurality of pairs of overlapping first and second segments. At least some of the pairs of overlapping first and second segments are configured so that the instantaneous direction of a first current formed on the first segment in response to RF radiation emitted by the second radiating element will be substantially opposite the instantaneous direction of a second current formed on the second segment in response to the RF radiation emitted by the second radiating element.
In some embodiments, the first and second conductive paths may each be meandered conductive paths. In some embodiments, the first meandered conductive path may include a plurality of first longitudinal segments that generally extend parallel to a longitudinal axis of the antenna and a plurality of first transverse segments that generally extend perpendicularly to the first longitudinal segments, and the second meandered conductive path may include a plurality of second longitudinal segments that generally extend parallel to the longitudinal axis of the antenna and a plurality of second transverse segments that generally extend perpendicularly to the second longitudinal segments. In such embodiments, at least some of the pairs of overlapping first and second segments comprise a respective one of the first transverse segments and a respective one of the second transverse segments. In some embodiments, substantially all of the first transverse segments may overlap a respective one of the second transverse segments. In some embodiments, in at least some of the pairs of overlapping first and second segments, one of the first and second segments may completely overlap the other of the first and second segments.
In some embodiments, the first and second meandered conductive paths may each have a wave structure (e.g., a sine wave, a square wave, etc.). A frequency of the wave structure of the first meandered conductive path may be different from a frequency of the wave structure of the second meandered conductive path.
In some embodiments, the antenna may further include a third radiating element extending forwardly from the reflector that is configured to operate in a third operating frequency band that encompasses higher frequencies than the second operating frequency band. The parasitic element may be configured to be substantially transparent to RF signals in the second operating frequency band and in the third operating frequency band.
In some embodiments, an average width of the first meandered conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second meandered conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
Pursuant to still further embodiments of the present invention, antennas are provided that include a first radiating element that is configured to operate in a first operating frequency band, a second radiating element that is configured to operate in a second operating frequency band that does not overlap with the first frequency band and that encompasses higher frequencies than the first operating frequency band, and a parasitic element that is positioned adjacent the first and second radiating elements, the parasitic element including a first conductive path having a wave structure with a first frequency and a second conductive path having a wave structure with a second frequency that is positioned behind the first conductive path, where the first frequency is different from the second frequency.
In some embodiments, an average width of the first conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
In some embodiments, the first conductive path may include a plurality of first longitudinal segments that generally extend parallel to a longitudinal axis of the antenna and a plurality of first transverse segments that generally extend perpendicularly to the first longitudinal segments, and the second conductive path may include a plurality of second longitudinal segments that generally extend parallel to the longitudinal axis of the antenna and a plurality of second transverse segments that generally extend perpendicularly to the second longitudinal segments. At least some of the first transverse segments may overlap respective ones of the second transverse segments. In some embodiments, substantially all of the first transverse segments may overlap a respective one of the second transverse segments. In some embodiments, at least some of the first transverse segments may completely overlap respective ones of the second transverse segments.
Any of the antenna discussed above may include a pair of parasitic elements that are positioned on a side of the first radiating element of the antenna. Each of the parasitic elements of the pair may include a first conductive path and a second conductive path that is positioned behind the first conductive path. A resonant frequency of the first parasitic element may differ from a resonant frequency of the second parasitic element so that together the pair of parasitic elements are resonant over a larger portion of the operating frequency band of the first radiating element. In some embodiments, the resonant frequency of the first parasitic element may differ from the resonant frequency of the second parasitic element by at least 5%.
In some embodiments, the two parasitic elements of the pair of parasitic elements may be implemented in a common printed circuit board. In some embodiments, the two parasitic elements of the pair of parasitic elements may be stacked in a forward dimension of the antenna (i.e., stacked in a direction extending forwardly from the plane defined by a reflector of the antenna).
Embodiments of the present invention relate generally to radiating elements for multi-band base station antennas and to related base station antennas. The multi-band base station antennas according to embodiments of the present invention may, for example, support three or more major air-interface standards in three or more cellular frequency bands and allow wireless operators to reduce the number of antennas deployed at base stations, lowering tower leasing costs.
A challenge in the design of multi-band base station antennas is reducing the effect of scattering of the RF signals at one frequency band by the radiating elements of other frequency bands. Scattering is undesirable as it may affect the shape of the antenna beam in both the azimuth and elevation planes, and the effects may vary significantly with frequency, which may make it hard to compensate for these effects. Moreover, at least in the azimuth plane, scattering tends to impact the beamwidth, beam shape, pointing angle, gain and front-to-back ratio in undesirable ways. The radiating elements according to certain embodiments of the present invention may be designed to have reduced impact on the antenna pattern of closely located radiating elements that transmit and receive signals in other frequency bands (i.e., reduced scattering).
Cloaking low-band radiating elements are known in the art. For example, U.S. Pat. No. 9,570,804 discloses a low-band radiating element that operates in the 696-960 MHz frequency band that includes dipole arms that are formed as a series of RF chokes in order to render the low-band radiating element substantially transparent to RF energy in the 1.7-2.7 GHz frequency band. U.S. Pat. Nos. 10,439,285 and 10,770,803 each disclose low-band radiating elements that operate in the 696-960 MHz frequency band that include dipole arms that are formed as a series of widened segments that are coupled by narrow inductive segments, which may be implemented as small, meandered trace segments on a printed circuit board. In each case, the narrow inductive segments act as high impedance elements for RF energy in the 1.7-2.7 GHz frequency band, rendering the low-band radiating elements substantially transparent to RF energy in that frequency range. As another example, U.S. Pat. No. 11,018,437 discloses a low-band radiating element that operates in the 696-960 MHz frequency band that includes two dipole arms that are substantially transparent to RF energy in the 1.7-2.7 GHz frequency band and another two dipole arms that are substantially transparent to RF energy in the 3.3-4.2 GHz frequency band. Additional cloaking radiating element designs are disclosed in Chinese Patent No. CN 112787061A, Chinese Patent No. CN 112164869A, Chinese Patent No. CN 112290199A, Chinese Patent No. CN 111555030A, Chinese Patent No. CN 112186333A, Chinese Patent No. CN 112186341A, Chinese Patent No. CN 112768895A, Chinese Patent No. CN 112821044A, Chinese Patent No. CN 213304351U, and Chinese Patent No. CN 112421219A.
Pursuant to embodiments of the present invention, multi-band base station antennas are provided that have linear arrays of first, second and third radiating elements that transmit and receive signals in respective first, second and third different frequency bands. In some embodiments, the first frequency band may comprise the 617-960 MHz frequency band or a portion thereof, the second frequency band may comprise the 1427-2690 MHz frequency band or a portion thereof, and the third frequency band may comprise the 3100-4200 MHz frequency band or a portion thereof. Each first radiating element may be a broadband decoupling radiating element that has dipole radiators that are substantially transparent to RF energy in both the second frequency band and in the third frequency band. By providing dipole radiators that are transparent to RF energy in two different frequency bands, it is possible to, for example, closely position the second radiating elements that operate in the second frequency band on one side of the first radiating elements and to closely position the third radiating elements that operate in the third frequency band on the other side of the first radiating elements without the first radiating elements materially impacting the antenna patterns formed by the second and third radiating elements. When the base station antennas according to embodiments of the present invention include arrays of radiating elements that operate in three different frequency bands, the radiating elements that operate in the lowest frequency band may be referred to as “low-band” radiating elements, the radiating elements that operate in the highest frequency band may be referred to as “high-band” radiating elements, and the radiating elements that operate in the intermediate frequency band may be referred to as “mid-band” radiating elements
The base station antennas according to some embodiments of the present invention may include low-band radiating elements that are designed to be substantially transparent to RF energy emitted by mid-band and/or high-band radiating elements that are included in the antenna. These low-band radiating elements may include first and second dipole radiators. The dipole radiators may be implemented in a “cross” arrangement to form a pair of center-fed +/−45° dipole radiators, as is well known in the art. Each dipole arm may comprise first and second stacked meandered conductive paths. For example, the dipole arms may be formed on a printed circuit board (or multiple printed circuit boards), with the first meandered conductive path of each dipole arm mounted on a first conductive layer of the printed circuit board and the second meandered conductive path of each dipole arm mounted on a second, different conductive layer of the printed circuit board. Each meandered conductive path may comprise a thin conductive trace that has a length that is much longer than its width, where the conductive trace is a non-linear conductive trace that follows a meandered path to increase the path length thereof. In some embodiments, the total length of each meandered conductive path (i.e., the sum of the length of each segment of the path) may be at least 75% longer than the straight line distance from the base of the meandered conductive path to the distal end of the meandered conductive path. In other embodiments, the total length of each meandered conductive path may be at least twice as long or at least three times as long as the straight line distance from the base of the meandered conductive path to the distal end of the meandered conductive path.
In some embodiments, the first and second meandered conductive paths may each have a wave shape, such as, for example, a general square wave structure. The direction of the effective current flow along each meandered conductive path may be along the longitudinal axis of the meandered conductive path (or longitudinal axes, if the meandered conductive path includes bends that divide the meandered conductive path into multiple sections). In some embodiments, each meandered conductive path may include both longitudinal segments that generally extend in the direction of the effective current flow and transverse segments that generally extend in a direction that is perpendicular to the direction of the effective current flow. At least some of the transverse segments of the first meandered conductive path may “overlap” respective ones of the transverse segments of the second meandered conductive path to form a plurality of pairs of overlapping transverse segments. Herein, first and second segments of respective first and second conductive paths “overlap” if an axis that is perpendicular to a plane defined by the first segment (or a plane defined by the portion of reflector behind the first and second segments if the first segment does not define a single plane) passes through both the first segment and the second segment.
As noted above, these low-band radiating elements may have certain features that allow the dipole arms thereof to pass low-band currents while suppressing the formation of currents in the mid-band and/or high-band frequency ranges in response to radiation emitted by nearby mid-band and/or high-band radiating elements. For example, the widths of the metal traces that form the first and second meandered conductive paths may be selected so that low-band currents can flow relatively freely on the meandered conductive paths while mid-band and/or high-band currents are substantially suppressed. The use of such narrow traces creates an inductive effect that appears as a high impedance to higher frequency RF signals, suppressing current formation by such radiation, while having a sufficiently low impedance for lower frequency RF signals. As another example, the length of each transverse segment (or the average length of the transverse segments) may be selected to be less than a quarter of a wavelength corresponding to the lowest frequency RF signals that are to be suppressed (or, alternatively, to less than a quarter of a wavelength corresponding to the center frequency of the operating frequency band of the mid-band radiating elements). This again facilitates suppression of the mid-band and/or high-band currents without substantially impacting the low-band currents.
As another example, the dipole arms may be designed so that for at least some of the pairs of overlapping transverse segments, the instantaneous direction of a first current formed on the first segment in response to mid-band and/or high-band RF radiation will be substantially opposite the instantaneous direction of a second current formed on the second segment in response to this mid-band/high-band RF radiation. This tends to result in cancellation of any mid-band and/or high-band currents. The dipole arms may be designed so that the same effect is suppressed with respect to low-band currents, allowing the low-band currents to freely flow on the dipole arms.
In one example embodiment of the present invention, an antenna is provided that includes a reflector. First and second radiating elements that are configured to operate in respective first and second operating frequency bands extend forwardly from the reflector. The first radiating element may comprise, for example, a low-band radiating element that is part of an array of low-band radiating elements, and the second radiating element may comprise, for example, a mid-band radiating element that is part of an array of mid-band radiating elements or a high-band radiating element that is part of an array of high-band radiating elements. The first radiating element includes a first dipole radiator having a first dipole arm and a second dipole arm and a second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first conductive path and a second conductive path that is positioned behind the first conductive path, where the first conductive path includes a plurality of first segments and the second conductive path includes a plurality of second segments. First segments in a subset of the first segments overlap respective ones of second segments in a subset of the second segments to form a plurality of pairs of overlapping first and second segments. At least some of the pairs of overlapping first and second segments are configured so that the instantaneous direction of a first current formed on the first segment in response to RF radiation emitted by the second radiating element will be substantially opposite the instantaneous direction of a second current formed on the second segment in response to the RF radiation emitted by the second radiating element.
In another example embodiment of the present invention, an antenna is provided that includes a reflector and first and second radiating elements that extend forwardly from the reflector and that operate in different frequency bands. The first radiating element includes a first dipole arm that has first and second spaced apart conductive paths, where a first segment of the first conductive path overlaps a second segment of the second conductive path. The first dipole arm is configured so that first and second currents that are induced on the respective first and second conductive paths in response to RF radiation emitted by the second radiating element each flow outwardly along the first dipole arm, but flow in substantially opposite directions along the respective first and second segments.
Pursuant to still further embodiments of the present invention, radiating elements are provided that include a first dipole radiator having a first pair of dipole arms and a second dipole radiator having a second pair of dipole arms. Each dipole arm includes a first meandered conductive path that extends from a base thereof to a distal end thereof and a second meandered conductive path that is positioned behind the first meandered conductive path.
Embodiments of the present invention will now be described in further detail with reference to the attached figures.
In the description that follows, the antenna 100 and the radiating elements included therein will be described using terms that assume that the antenna 100 is mounted for normal use on a tower with a longitudinal axis of the antenna 100 extending along a vertical axis and the front surface of the antenna 100 mounted opposite the tower pointing toward the coverage area for the antenna 100.
As shown in
A plurality of dual-polarized radiating elements are mounted to extend forwardly from the reflector 214 (the radiating elements extend upwardly from the reflector 214 in the views of
In the depicted embodiment, the first and second planar arrays 240, 250 of high-band radiating elements 244, 254 are positioned between the linear arrays 220-1, 220-2 of low-band radiating elements 224, and each linear array 220 of low-band radiating elements 224 is positioned between the planar arrays 240, 250 of high-band radiating elements 244, 254 and a respective one of the linear arrays 230 of mid-band radiating elements 234. It will be appreciated that antenna 100 illustrates one typical layout of arrays of low-band, mid-band and high-band radiating elements. Many other array configurations are routinely used based on applications and customer requirements. The radiating elements according to embodiments of the invention may be used in arrays having any suitable configuration.
The low-band radiating elements 224 may be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may comprise the 617-960 MHz frequency range or a portion thereof (e.g., the 617-896 MHz frequency band, the 696-960 MHz frequency band, etc.). The mid-band radiating elements 234 may be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band may comprise the 1427-2690 MHz frequency range or a portion thereof (e.g., the 1710-2200 MHz frequency band, the 2300-2690 MHz frequency band, etc.). The high-band radiating elements 244, 254 may be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may comprise the 3300-4200 MHz frequency range or a portion thereof. The low-band linear arrays 220 may or may not be configured to transmit and receive signals in the same portion of the first frequency band. For example, in one embodiment, the low-band radiating elements 224 in the first linear array 220-1 may be configured to transmit and receive signals in the 700 MHz frequency band and the low-band radiating elements 224 in the second linear array 220-2 may be configured to transmit and receive signals in the 800 MHz frequency band. In other embodiments, the low-band radiating elements 224 in both the first and second linear arrays 220-1, 220-2 may be configured to transmit and receive signals in the same frequency band to support the use of multi-input-multi-output (“MIMO”) communication techniques. The mid-band and high-band radiating elements 234, 244, 254 in the different mid-band and high-band arrays 230, 240, 250 may similarly have any suitable configuration. The radiating elements 224, 234, 244, 254 may be dual polarized radiating elements, and hence each array 220, 230, 240250 may be used to form a pair of antenna beams, namely an antenna for each of the two polarizations at which the dual-polarized radiating elements are designed to transmit and receive RF signals.
While not shown in the figures, the radiating elements 224, 234, 244, 254 may be mounted on feed boards that couple RF signals to and from the individual radiating elements 224, 234, 244, 254. One or more radiating elements 224, 234, 244, 254 may be mounted on each feed board. Cables may be used to connect each feed board to other components of the antenna such as diplexers, phase shifters or the like.
While cellular network operators are interested in deploying antennas that have a large number of arrays of radiating elements in order to reduce the number of base station antennas required per base station, increasing the number of arrays typically increases the width of the antenna. Both the weight and wind loading of a base station antenna increase with increasing width, and thus wider base station antennas tend to require structurally more robust antenna mounts and antenna towers, both of which can significantly increase the cost of a base station. Accordingly, cellular network operators may place limitations on the widths of base station antennas (where the limits may depend on the application for the antenna). For example, for many applications, cellular network operators may require that the width of a base station antenna be below 500 mm. This can be challenging in base station antennas that include two linear arrays of low-band radiating elements, since most conventional low-band radiating elements that are designed to serve a 120° sector have a width of about 200 mm or more.
The width of a multi-band base station antenna may be reduced by decreasing the separation between adjacent arrays. However, as the separation is reduced, increased coupling between the radiating elements of the different arrays occurs, and this increased coupling may impact the shapes of the antenna beams generated by the arrays in undesirable ways. For example, a low-band cross-dipole radiating element will typically have dipole radiators that have a length that is approximately ½ a wavelength of the center frequency of the designed operating frequency band for the radiating element. If the low-band radiating element is designed to operate in the 700 MHz frequency band, and the mid-band radiating elements are designed to operate in the 1400 MHz frequency band, the length of the low-band dipole radiators will be approximately one wavelength at the mid-band operating frequency. As a result, each dipole arm of a low-band dipole radiator will have a length that is approximately ½ a wavelength at the mid-band operating frequency, and hence RF energy transmitted by the mid-band radiating elements will tend to couple to the low-band radiating elements since such RF energy will be resonant in a ½ wavelength dipole arm.
When mid-band and/or high-band RF energy couples to the dipole arms of a low-band radiating element, mid-band and/or high-band currents are induced on the dipole arms. Such induced currents are particularly likely to occur when the low-band and mid-band radiating elements are designed to operate in frequency bands having center frequencies that are separated by about a factor of two (or four), since a low-band dipole arm having a length that is a quarter wavelength of the low-band operating frequency will, in that case, have a length of approximately a half wavelength (or a full wavelength) of the higher band operating frequency. The induced currents generate mid-band and/or high-band RF radiation that is emitted from the low-band dipole arms. The mid-band/high-band RF energy emitted from the dipole arms of the low-band resonating element distorts the antenna beam of the mid-band and/or high-band arrays since the radiation is being emitted from a different location than intended. The greater the extent that mid-band/high-band currents are induced on the low-band dipole arms, the greater the impact on the characteristics of the antenna beams generated by the mid-band and high-band arrays.
The low-band radiating elements 224 according to embodiments of the present invention may be designed to be substantially transparent to RF energy emitted by the mid-band and high-band radiating elements 234, 244, 254. As such, even if the mid-band and high-band radiating elements 234, 244, 254 are in close proximity to the low-band radiating elements 224, the above-discussed undesired coupling of mid-band and/or high-band RF energy onto the low-band radiating elements 224 may be significantly reduced.
Referring to
The feed stalks 310 may each comprise a printed circuit board 312 that has RF transmission lines 314 formed thereon. These RF transmission lines 314 carry RF signals between a feed board (not shown) that is mounted on the reflector 214 and the dipole radiators 322. Each feed stalk 310 may further include a hook balun 316. A first of the feed stalks 310-1 may include a front slit and the second of the feed stalks 310-2 includes a back slit. These slits allow the two feed stalks 310 to be assembled together to form a forwardly extending column that has generally x-shaped vertical cross-sections. Rear portions of each feed stalk 310 may include projections that are inserted through slits in the feed board (not shown) to mount the radiating element 300 thereon. The RF transmission lines 314 on the respective feed stalks 310 may center feed the dipole radiators 322-1, 322-2.
The azimuth half power beamwidths of each low-band radiating element 300 may be in the range of 55 degrees to 85 degrees. In some embodiments, the azimuth half power beamwidth of each low-band radiating element 300 may be approximately 65 degrees in the center of the operating frequency band for the low-band radiating element 300.
Each dipole arm 330 may be between approximately 0.2 to 0.35 of an operating wavelength in length, where the “operating wavelength” refers to the wavelength corresponding to a center frequency of the operating frequency band of the radiating element 300. For example, if the low-band radiating elements 300 are designed to transmit and receive signals across the 694-960 MHz frequency band, then the center frequency of the operating frequency band would be 827 MHz and the corresponding operating wavelength would be 36.25 cm.
The dipole radiator printed circuit board 320 includes a dielectric substrate 326 that has a first conductive layer 324 formed on a front side thereof and a second conductive layer 328 formed on a rear side thereof as is best shown in
As shown best in
Referring again to
While positioning the low-band radiating elements 224 (300) so that they overlap the mid-band and/or the high-band radiating elements 234, 244, 254 may advantageously facilitate reducing the width of the base station antenna 100, this approach may significantly increase the coupling of RF energy transmitted by the mid-band and/or the high-band radiating elements 234, 244, 254 onto the low-band radiating elements 224 (300), and such coupling may degrade the antenna beams formed by the arrays 230, 240, 250 of mid-band and/or high-band radiating elements 234, 244, 254.
In order to reduce such coupling, the low-band radiating elements 300 may be designed to have dipole arms 330 that are substantially “transparent” to radiation emitted by both the mid-band radiating elements 234 and the high-band radiating elements 244, 254. This may be challenging, as the mid-band radiating elements 234 may operate (in some cases) at frequencies as low as 1427 MHz and the high-band radiating elements 244, 254 may operate (in some cases) at frequencies as high as 4200 MHz. Thus, ideally the low-band radiating elements 300 are substantially transparent to RF energy in the 1427-4200 MHz frequency range, while allowing currents in the 617-960 MHz frequency range to flow freely on the dipole arms 330. Herein, a dipole arm of a radiating element that is configured to transmit RF energy in a first frequency band is considered to be “transparent” to RF energy in a second, different frequency band RF energy if the RF energy in the second frequency band poorly couples to the dipole arm. Accordingly, if a dipole arm of a first radiating element that is transparent to a second frequency band is positioned so that it overlaps a second radiating element that transmits in the second frequency band, the addition of the first radiating element will not materially impact the antenna pattern of the second radiating element.
Referring to
As shown in
As can be seen from
The pairs 360 of overlapping first and second transverse segments 348, 358 may be configured to help suppress currents from forming on the first and second meandered conductive paths 340, 350 in response to RF radiation emitted by either the mid-band radiating elements 234 or the high-band radiating elements 244, 254 that may be positioned near the low-band radiating element 300. In particular, each pair 360 of overlapping first and second transverse segments 348, 358 may be configured so that the instantaneous direction of a first current formed on the first transverse segment 348 of the pair 360 in response to RF radiation emitted by the mid-band or high-band radiating elements 234, 244, 254 will be substantially opposite the instantaneous direction of a second current formed on the second transverse segment 358 of the pair 360 in response to the mid-band or high-band RF radiation. As such, the first and second currents “flowing” on the first and second transverse segments 348, 358 of each pair 360 of overlapping first and second transverse segments 348, 358 will tend to cancel each other out, suppressing the formation of currents on the low-band dipole arm 330 in response to RF radiation emitted by the nearby mid-band or high-band radiating elements 234, 244, 254.
The low-band radiating element 300 may have certain features that allow the dipole arms 330 thereof to pass low-band currents while suppressing the formation of currents in the mid-band and/or high-band frequency ranges in response to radiation emitted by nearby mid-band and/or high-band radiating elements 234, 244, 254. For example, the widths w (see
As another example, the “length” of each transverse segment 348, 358 (i.e., the distance the transverse segments 348, 358 extend along their longitudinal axis) or, alternatively, the average length of all of the transverse segments on a given conductive path, may be selected to be less than one quarter of a wavelength corresponding to the lowest frequency RF signals that are to be suppressed. Thus, for example, the length of each transverse segment 348, 358 (or the average lengths of the transverse segments 348, 358 on each conductive path 340, 350) may be selected in example embodiments to be less than one-quarter of a wavelength corresponding to a frequency of 1427 MHz or a frequency of 1690 MHz (example lowest frequencies of the operating frequency band of the mid-band radiating elements 234). In other embodiments, an average length of the transverse segments 348 on the first meandered conductive path 340 as well as an average length of the transverse segments 358 on the second meandered conductive path 350 may each be less than ¼ of a wavelength corresponding to the center frequency of the operating frequency band of the mid-band radiating elements 234.
As another example, the dipole arms 330 may be designed so that for at least some of the pairs of overlapping transverse segments 360 the direction of instantaneous current flow on the transverse segments 348 of the first meandered conductive path 340 is generally opposite the direction of instantaneous current flow on the transverse segments 358 of second meandered conductive path 350. This tends to result in cancellation of any mid-band and/or high-band currents, but has only a very limited cancellation effect for low-band currents. This can best be seen with reference to
As shown in
As shown in
As can further be seen in
Referring to
Referring to
Referring to
Referring to
It will also be appreciated that the low-band radiating elements according to embodiments of the present invention are not limited to having dipole arms with the shape of the dipole arms 330. Instead, the dipole arms may have any appropriate shape such as line shapes, circular shapes, oval shapes, square shapes, etc. For example,
While the dipole arms of the low-band radiating elements described above are implemented on one or more dipole radiator printed circuit boards, it will be appreciated that embodiments of the present invention are not limited thereto. For example, in other embodiments, any of the above-described radiating elements may be implemented using sheet metal dipole arms that are mounted on a dielectric support. In such embodiments, the first and second meandered conductive paths of each of the above-described radiating elements may be formed by stamping the appropriately shaped structures from sheet metal. The sheet metal-formed first and second meandered conductive paths may then be mounted on opposed sides of a dielectric substrate to form each dipole arm. U.S. Patent Publication No. 2020/0161748 (“the '748 publication”) describes techniques for implementing dipole arms as sheet metal on plastic dipole arms. Any of the dipole arms disclosed herein may be implemented using the sheet metal on dielectric designs disclosed in the '748 publication, with sheet metal patterns having the respective first and second conductive paths implemented on either side of a dielectric (e.g., plastic) support. The entire content of the '748 publication is incorporated herein by reference.
So-called “parasitic elements” are routinely used in base station antennas to improve the performance of an associated array of radiating elements included in the antenna. Parasitic elements refer to structures that include one or more conductive patterns that are not coupled to the feed network of the associated array of radiating elements. The parasitic elements are used to alter the radiation patterns or “antenna beams” generated by the associated array of radiating elements in desirable ways.
Parasitic elements are typically mounted forwardly of a reflector of a base station antenna adjacent the radiating elements of the associated array of radiating elements. The parasitic elements are typically designed to be resonant in an operating frequency band of the associated array of radiating elements so that RF energy emitted by the radiating elements will induce currents on the parasitic elements, and these currents cause the parasitic elements to reradiate the RF received energy. The parasitic elements may, for example, have an electrical length that is between one-quarter and one-half of a wavelength that corresponds to a center frequency of the operating frequency band of the associated array of radiating elements. Parasitic elements are typically formed from sheet metal or using printed circuit boards, although other implementations are possible.
Parasitic elements are often used to narrow the azimuth beamwidth of the antenna beams formed by the associated linear array of radiating elements. To accomplish this, first and second columns of parasitic elements may, for example, be mounted along either side of an associated linear array of radiating elements (i.e., each column of parasitic elements extends in the longitudinal direction, and hence parallel to a longitudinal axis of the base station antenna). RF energy transmitted by the associated array of radiating elements that is emitted at relatively larger azimuth angles may impinge upon the parasitic elements and induce currents thereon. These currents cause the parasitic elements to reradiate the RF energy. The parasitic elements are positioned so that the RF energy that is reradiated from the parasitic elements is primarily directed toward the boresight pointing direction of the associated array of radiating elements, thereby focusing the antenna beam in the azimuth plane. The parasitic elements may be designed so that the redirected RF energy substantially constructively combines with the RF energy that is emitted at smaller azimuth angles by the array of radiating elements. Generally speaking, the parasitic elements allow a base station antenna manufacturer to use smaller radiating elements while still achieving desired azimuth beamwidth performance for the antenna beams generated by arrays of these smaller radiating elements.
When parasitic elements are used to narrow the azimuth beamwidth of the antenna beams generated by a linear array in the manner discussed above, the parasitic elements are typically mounted forwardly of the reflector and extending parallel to the longitudinal axis of the base station antenna.
Parasitic elements may also be used to, for example, improve the cross-polarization discrimination of an array of radiating elements. This is particularly true with respect to multi-column arrays of radiating elements that are used in beamforming antennas. When the antenna beams generated by such arrays are scanned (typically in the azimuth plane) to large scanning angles, the cross-polarization discrimination of the array often degrades (meaning that the amount of RF energy transmitted at a first polarization that is converted to a second, orthogonal polarization is increased). Parasitic elements that extend forwardly from the reflector may be mounted around the radiating elements of such an array in order to improve the cross-polarization discrimination performance of the array.
One potential difficulty that arises when adding parasitic elements to a base station antenna is that the parasitic elements can impact the antenna beams of more than one array of radiating elements. For example, many base station antennas include a vertically-extending linear array of low-band radiating elements and a pair of vertically-extending linear arrays of mid-band radiating elements that are mounted on either side of the low-band array. In order to keep the width of such base station antennas small, each mid-band linear array may be positioned very close to the low-band array. Because of this close spacing, at least some of the mid-band radiating elements may be mounted “underneath” the low-band radiating elements, meaning that for at least some of the mid-band radiating elements, an axis that is perpendicular to the reflector of the base station antenna extends through both the mid-band radiating element and one of the low-band radiating elements. Herein, when this condition is met the low-band radiating element may be referred to as “overlapping” the mid-band radiating element. In other base station antennas the radiating elements of a low-band array may overlap the radiating elements of a high-band array, or may overlap radiating elements of both a mid-band array and a high-band array.
When radiating elements of different arrays are overlapped as described above, or otherwise are in close proximity, the parasitic elements that are positioned close to a first array of radiating elements are often also close to radiating elements of one or more additional arrays. Moreover, the low-band, mid-band and high-band frequency ranges include frequencies that differ by a factor of two or four, which means that parasitic elements that are resonant in one of the low-band, mid-band and high-band frequency band are often resonant in another of the low-band, mid-band and high-band frequency bands. For example, a parasitic element that has an electrical length of one quarter wavelength at 900 MHz, will have an electrical length of a half wavelength at 1800 MHz and an electrical length of one wavelength at 3600 MHz. Notably, 900 MHz is within the low-band cellular frequency range, 1800 MHz is within the mid-band cellular frequency range, and 3600 MHz is within the high-band cellular frequency range. Thus, the above-described parasitic element may be resonant in all three frequency bands, and hence will tend to impact the antenna beams of any low-band, mid-band and high-band arrays that are in close proximity to the parasitic element.
In practice, it can be difficult to design and position a parasitic element so that it improves the shape of the antenna beams generated by near-by arrays of radiating elements that operate in different frequency bands. In order to address this problem, so-called “cloaking” parasitic elements have been developed. A cloaking parasitic element refers to a parasitic element that is designed to be resonant in an operating frequency band of a first array of radiating elements, but is designed to be substantially transparent to RF energy in the operating frequency band of a second array of radiating elements. This ensures that the parasitic elements only materially impact the antenna beams generated by the first array of radiating elements.
One issue with the conventional parasitic elements of
Pursuant to further embodiments of the present invention, parasitic elements for base station antennas are provided that are designed to be resonant with respect to RF energy emitted by low-band radiating elements while being substantially transparent to RF energy emitted by both mid-band and/or high-band radiating elements. In an example embodiment, these parasitic elements may be resonant in some or all of the low-band frequency range (617-960 MHz) while exhibiting good cloaking behavior over the full 1.4-5.8 GHz frequency band. As such, the cloaking parasitic elements according to embodiments of the present invention may be used across the full range of base station antennas, and may exhibit improved performance as compared to conventional cloaking parasitic elements.
The cloaking parasitic elements according to embodiments of the present invention may comprise first and second stacked meandered conductive paths and may, for example, be substantially identical to the above-described cloaking dipole arms. In other words, the parasitic elements according to embodiments of the present invention may have the same design as the dipole arms of the above-discussed radiating elements according to embodiments of the present invention.
As shown in
As best shown in
At least some of the first transverse segments 1274 overlap respective ones of the second transverse segments 1284 to form a plurality of pairs 1290 of overlapping first and second transverse segments 1274, 1284. As noted above, first and second segments of a conductive path “overlap” if an axis that is perpendicular to a plane defined by the first segment passes through both the first segment and the second segment. In the depicted embodiment, a frequency of the square wave defined by the second meandered conductive path 1280 is twice the frequency of the square wave defined by the first meandered conductive path 1270. Consequently, each first transverse segment 1274 of the first meandered conductive path 1270 overlaps a corresponding second transverse segment 1284 of the second meandered conductive path 1280, but only half the second transverse segments 1284 have a corresponding overlapping first transverse conductive segment 1274.
As with the similar dipole arms discussed above, the pairs 1290 of overlapping first and second transverse segments 1274, 1284 are designed to suppress currents from forming on the first and second meandered conductive paths 1270, 1280 in response to RF radiation emitted by nearby mid-band or high-band radiating elements. In particular, each pair 1290 of overlapping first and second transverse segments 1274, 1284 may be configured so that the instantaneous direction of a first current formed on the first transverse segment 1274 of the pair 1290 in response to RF radiation emitted by nearby mid-band or high-band radiating elements will be substantially opposite the instantaneous direction of a second current formed on the second transverse segment 1284 of the pair 1290 in response to the mid-band or high-band RF radiation, and these opposite currents cancel each other out.
The widths of the metal traces that form the meandered conductive paths 1270, 1280 may be selected so that low-band currents can flow relatively freely on the meandered conductive paths 1270, 1280, while mid-band and/or high-band currents are substantially suppressed. In some embodiments, the width of each meandered conductive path 1270, 1280 may be selected, for example, to be smaller than 0.05 of a wavelength corresponding to the lowest frequency RF signals that are to be suppressed. The use of conductive traces with narrow widths creates an inductive effect that appears as a high impedance to higher frequency RF signals, suppressing current formation by such radiation, while having a sufficiently low impedance for lower frequency RF signals (allowing currents generated by such lower frequency RF signals to flow on the conductive paths 1270, 1280). The meandered conductive paths 1270, 1280 form an LC resonant circuit. By selecting an appropriate width for the traces forming the meandered conductive paths 1270, 1280, the LC circuit may appear as an open circuit at a resonant frequency thereof, which may be at the mid-band/high-band frequencies. Thus, the parasitic element 1252 is designed to allow low-band currents to flow thereon while suppressing formation of mid-band and high-band currents. The suppression will tend to increase with increasing frequency, providing wideband performance.
Additionally, the “length” of each transverse segment 1274, 1284 or, alternatively, the average length of all of the transverse segments on a given conductive path, may be selected to be less than one quarter of a wavelength corresponding to the lowest frequency RF signals that are to be suppressed. Thus, for example, the length of each transverse segment 1274, 1284 (or the average lengths of the transverse segments 1274, 1284 on each conductive path 1270, 1280) may be selected in example embodiments to be less than one-quarter of a wavelength corresponding to a frequency of 1427 MHz or a frequency of 1690 MHz (example lowest frequencies of the operating frequency band of the mid-band radiating elements). In other embodiments, an average length of the transverse segments 1274 on the first meandered conductive path 1270 as well as an average length of the transverse segments 1284 on the second meandered conductive path 1280 may each be less than ¼ of a wavelength corresponding to the center frequency of the operating frequency band of the mid-band radiating elements.
It can also be seen from
The parasitic element 1252 may be mounted in the manner shown in
Referring first to
Referring next to
While the parasitic elements 1352 shown in
It will also be appreciated that the parasitic elements according to embodiments of the present invention may be mounted in other orientations. For example,
Referring again to
Pursuant to further embodiments of the present invention, base station antennas are provided that include arrays of radiating elements that have associated arrays of parasitic elements that include at least two different parasitic element designs. As discussed above with reference to, for example,
If higher passband performance is necessary, each parasitic element 1352 in, for example, the base station antennas 1300A, 1300B of
As the above description makes clear, pursuant to further embodiments of the present invention, base station antennas are provided that include a reflector and first and second arrays of radiating elements that extend forwardly from the reflector. The radiating elements of the first array operate in a lower operating frequency band (e.g., the 617-960 MHz frequency band or a portion thereof) and the radiating elements of the second array operate in a higher operating frequency band (e.g., the 1427-2690 MHz frequency band or a portion thereof, or the 3.1-5.8 GHz frequency band, or a portion thereof). These antennas also include one or more parasitic elements. For example, the antennas can include a first vertically-extending column of parasitic elements that is positioned on a first side of the first array and a second vertically-extending column of parasitic elements that is positioned on a second, opposed, side of the first array. At least some of the parasitic elements include first and second conductive paths, where the second conductive path is positioned behind the first conductive path. The first conductive path includes a plurality of first segments and the second conductive path includes a plurality of second segments. A subset of the first segments overlap respective ones of the second segments in a subset of the second segments to form a plurality of pairs of overlapping first and second segments. At least some of the pairs of overlapping first and second segments are configured so that the instantaneous direction of a first current formed on the first segment in response to RF radiation emitted by the radiating elements in the second array will be substantially opposite the instantaneous direction of a second current formed on the second segment in response to the RF radiation emitted by the radiating elements of the second array. As a result, the currents induced on the first and second segments may substantially cancel out such that the parasitic elements may be substantially transparent to RF radiation in the second operating frequency band. The parasitic elements may be resonant at frequencies within the first operating frequency band so that the parasitic element will alter properties of the antenna beams generated by the first array in a desirable array. For example, the parasitic elements may narrow an azimuth beamwidth of the antenna beams generated by the first array or may improve the cross-polarization discrimination performance of radiating elements in the first array.
The first and second conductive paths of the above-described parasitic elements may have wave structures (e.g., a square wave, a sine wave, etc.) in some embodiments. The wave structure of the first conductive path may have a first frequency, and the wave structure of the second conductive path may have a second frequency that is different from the first frequency. In some embodiments, the first and second frequencies may differ by substantially multiples of an integer (e.g., a factor of two, a factor of three, etc.).
In some embodiments, the first and second conductive paths may each be meandered conductive paths. The first meandered conductive path may include a plurality of first longitudinal segments that generally extend parallel to a longitudinal axis of the antenna and a plurality of first transverse segments that generally extend perpendicularly to the first longitudinal segments, and the second meandered conductive path may include a plurality of second longitudinal segments that generally extend parallel to the longitudinal axis of the antenna and a plurality of second transverse segments that generally extend perpendicularly to the second longitudinal segments. In some embodiments, substantially all of the first transverse segments may overlap a respective one of the second transverse segments. In some embodiments, in at least some of the pairs of overlapping first and second segments, one of the first and second segments may completely overlap the other of the first and second segments.
In some embodiments, an average width of the first conductive path may be less than 0.05 of a wavelength corresponding to a center frequency of the second operating frequency band, and an average width of the second conductive path may be less than 0.05 of the wavelength corresponding to the center frequency of the second operating frequency band.
The discussion of the parasitic elements according to embodiments of the present invention has focused on parasitic elements having a design that corresponds to the dipole arms of the radiating element described above with reference to
When such “double” (or triple) parasitic elements are used, one of the “double” parasitic elements 1552-1, 1552-2 shown in
It will be appreciated that many modifications may be made to the above described radiating elements and antennas without departing from the scope of the present invention. For example, the low-band radiating elements described above include a dipole radiator printed circuit board, and each of the four dipole arms are implemented in the dipole radiator printed circuit board. It will be appreciated, however, that in other embodiments, more than one dipole radiator printed circuit board may be used. For example, each dipole arm could be implemented on its own dipole radiator printed circuit board.
While the example embodiments described above have low-band radiating elements that are designed to be transparent to RF energy radiated in two higher frequency bands, it will be appreciated that embodiments of the present invention are not limited thereto. For example, in other embodiments, mid-band radiating elements may be provided that have first dipole arms that are configured to be substantially transparent to RF energy in a lower frequency band and second dipole arms that are configured to be substantially transparent to RF energy in a higher frequency band.
Embodiments of the present invention have been described above with reference to the accompanying drawings, in which 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 numbers 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 like fashion (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 a relationship of one element, layer or region 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.
Aspects and elements of all of the embodiments disclosed above can be combined in any way and/or combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.
The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 63/241,676, filed Sep. 8, 2021 and to U.S. Provisional Patent Application Ser. No. 63/342,759, filed May 17, 2022, the entire content of each of which is incorporated herein by reference.
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