Patent Application
20230299469
The present application claims priority to Indian Provisional Patent Application No. 202241014927, filed Mar. 17, 2022, the entire content of which is incorporated herein by reference.
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 or “cells” that are served by respective base stations. Each base station may include one or more base station antennas that are configured to provide two-way radio frequency (“RF”) communications with 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 generate radiation patterns of “antenna beams” having azimuth Half Power Beamwidths (“HPBWs”) of approximately 65°. Typically, the base station antennas are mounted on a tower or other raised structure, with the antenna beams that are generated by the base station antennas directed outwardly. Base station antennas are often implemented as linear arrays or planar phased arrays of radiating elements.
To increase capacity, base station antennas that include beamforming arrays and/or arrays that are configured to operate with massive multi-input-multi-output (“MIMO”) radios have been introduced in recent years. A beamforming array refers to an antenna array that includes multiple columns of radiating elements. RF signals that are to be transmitted by the beamforming array are broken into sub-components that are transmitted through respective groups, or “sub-arrays,” of one or more radiating elements. The amplitudes and phases of the sub-components are adjusted by the radio so that the beamforming array generates antenna beams having reduced (narrower) beamwidths in, for example, the horizontal or “azimuth” plane, which increases the directivity or “gain” of the antenna, thereby increasing the supportable throughput. MIMO refers to a communication technique in which a data stream is broken into pieces that are simultaneously transmitted using certain coding techniques over multiple relatively uncorrelated transmission paths between a transmitting station and a receiving station. Multi-column antenna arrays may be used for MIMO transmissions, where each column in the array may be connected to a port of a MIMO radio and used to transmit/receive one of the multiple data streams. In practice, as orthogonal polarizations tend to be highly uncorrelated, the radiating elements in a MIMO array are typically implemented as dual-polarized radiating elements, allowing each column in the MIMO array to be connected to two ports on the radio (where the first port is connected to the first-polarization radiators of the radiating elements in the column, and the second port is connected to the second-polarization radiators of the radiating elements in the column). This technique can effectively halve the number of columns of radiating elements required, as each physical column of the array contains two independent columns of radiators.
Pursuant to embodiments of the present invention, a base station antenna may include a first antenna array having a vertical stack of first sub-arrays that each have a plurality of first-band radiating elements. The base station antenna may include a second antenna array having a vertical stack of second sub-arrays that each have a plurality of first-band radiating elements. The first sub-arrays may share a vertical column of first-band radiating elements with the second sub-arrays. Moreover, the first-band radiating elements that are in the shared vertical column may be configured to have a fixed phase delay applied thereto that is different from fixed phase delays of the first-band radiating elements of portions of the first and second sub-arrays that are outside of the shared vertical column.
In some embodiments, the first and second sub-arrays may each be L-shaped sub-arrays. Moreover, the base station antenna may include a reflector having the first and second antenna arrays thereon. A width of the reflector may be narrower than 700 millimeters, and the first-band radiating elements may be configured to operate in all or part of a 617-960 megahertz frequency band.
According to some embodiments, the base station antenna may include a plurality of first power dividers that are coupled to the first sub-arrays, respectively. Moreover, the base station antenna may include a plurality of second power dividers that are coupled to the second sub-arrays, respectively.
In some embodiments, each of the first and second power dividers may include a three-way power divider. Moreover, the base station antenna may include a plurality of phase shifters. A first of the first power dividers may be coupled between a first of the phase shifters and a first of the first sub-arrays. A first of the second power dividers may be coupled between a second of the phase shifters and a first of the second sub-arrays.
According to some embodiments, the first and second sub-arrays may each include three first-band radiating elements that are configured to have three different fixed phase delays, respectively, applied thereto. Moreover, a single one of the three first-band radiating elements may be in the shared vertical column.
In some embodiments, the base station antenna may include a plurality of second-band radiating elements. Some, but not all, of the first sub-arrays may overlap the second-band radiating elements in a forward direction. Some, but not all, of the second sub-arrays may overlap the second-band radiating elements in the forward direction. The second band may be higher than the first band. Moreover, the shared vertical column may not overlap any of the second-band radiating elements in the forward direction.
A base station antenna, according to some embodiments, may include a first outer column of radiating elements of a first array. The first array may include a plurality of first non-rectangular sub-arrays. The base station antenna may include a second outer column of radiating elements of a second array. The second array may include a plurality of second non-rectangular sub-arrays. The base station antenna may include an inner column of radiating elements that is shared by the first and second arrays and is between the first and second outer columns. Moreover, the base station antenna may include a plurality of power dividers. The power dividers may include first power dividers that are coupled to the first non-rectangular sub-arrays, respectively, and second power dividers that are coupled to the second non-rectangular sub-arrays, respectively. A first of the first non-rectangular sub-arrays may include first through third radiating elements. The first and second radiating elements may be in the first outer column and may be coupled by first and second RF transmission lines, respectively, to a first of the first power dividers. The first and second RF transmission lines may have different first and second lengths, respectively. The third radiating element may be in the inner column and may be coupled to the first of the first power dividers by a third RF transmission line having a third length that is longer than each of the first and second lengths.
In some embodiments, a first of the second non-rectangular sub-arrays may include fourth through six radiating elements. The fourth and fifth radiating elements may be in the second outer column and may be coupled by fourth and fifth RF transmission lines, respectively, to a first of the second power dividers. The fourth and fifth RF transmission lines may have different fourth and fifth lengths, respectively. The sixth radiating element may be in the inner column and may be coupled to the first of the second power dividers by a sixth RF transmission line having a sixth length that is longer than each of the fourth and fifth lengths.
According to some embodiments, the first, third, and fourth radiating elements may be in a first row. The second, sixth, and fifth radiating elements may be in a second row. Moreover, the base station antenna may include a reflector having the first and second arrays thereon, a plurality of first metal isolation walls protruding forward from a first edge of the reflector, and a plurality of second metal isolation walls protruding forward from a second edge of the reflector that is opposite the first edge. The first row may be between a first of the first metal isolation walls and a first of the second metal isolation walls. The second row may be between a second of the first metal isolation walls and a second of the second metal isolation walls.
In some embodiments, the base station antenna may include a metal isolation wall that is between the third radiating element and the sixth radiating element. Moreover, the first through sixth RF transmission lines may include first through sixth cables, respectively. The base station antenna may include a plurality of RF ports and a plurality of phase shifters that are coupled to the RF ports, respectively. A first of the phase shifters may be coupled between a first of the RF ports and the first of the first power dividers. A second of the phase shifters may be coupled between a second of the RF ports and the first of the second power dividers.
A base station antenna, according to some embodiments, may include a first antenna array having a vertical stack of first sub-arrays that each have a plurality of first-band radiating elements. The base station antenna may include a second antenna array having a vertical stack of second sub-arrays that each have a plurality of first-band radiating elements. The first sub-arrays may share a plurality of vertical columns of first-band radiating elements with the second sub-arrays. In some embodiments, the first and second sub-arrays may each be triangle-shaped sub-arrays.
According to some embodiments, the first and second sub-arrays each have three first-band radiating elements. The three first-band radiating elements may be in three of the vertical columns, respectively. Moreover, in each of the three of the vertical columns, the first-band radiating elements of the first antenna array may repeatedly alternate with the first-band radiating elements of the second antenna array. The base station antenna may include a plurality of RF ports. Each of the first and second antenna arrays may be coupled to a respective one of the RF ports per polarization.
Pursuant to embodiments of the present invention, base station antennas are provided that have a narrower width, lower cost, and lighter weight than conventional base station antennas that include four columns of low-band radiating elements (i.e., radiating elements that operate in all or part of the 617-960 megahertz (“MHz”) frequency band). Base station antennas that include three columns of low-band radiating elements may, in some embodiments, use 25% fewer low-band dipole radiating elements, and may thereby reduce antenna width from about 900 millimeters (“mm”) to about 640 mm. As an example, such a “three-column” base station antenna according to some embodiments may have two arrays that include two outer columns, respectively, of low-band radiating elements and that share an inner column of low-band radiating elements. Though the shared inner column may increase the risk of reduced isolation and/or grating lobe problems, some embodiments can reduce/solve such problems by applying different amounts of fixed phase delay to respective low-band radiating elements that are in a sub-array. In another example, sub-arrays of the two arrays may each have radiating elements in all three columns, and may thereby provide a narrower beamwidth.
Embodiments of the present invention will now be discussed in greater detail with reference to the attached figures.
As shown in
Moreover, the sub-arrays SUB-1 may be arranged in a pattern along a vertical direction V. and thus may collectively be referred to as a first “vertical stack.” The sub-arrays SUB-2 may be arranged in a similar/complementary pattern along the direction V, and thus may collectively be referred to as a second vertical stack. The second vertical stack of the sub-arrays SUB-2 is side-by-side, and interlaced/interleaved (due to the inner column 170-2), with the first vertical stack of the sub-arrays SUB-1.
The inner column 170-2 is between, in a horizontal direction H, the two outer columns 170-1, 170-3. Each of the sub-arrays SUB-1. SUB-2 includes a single radiating element RE-L that is in the inner column 170-2. The inner column 170-2 may thus be referred to herein as a “shared” column 170S, as it includes radiating elements RE-L from both the first array 112-1 and the second array 112-2. In the inner column 170-2, radiating elements RE-L of the first array 112-1 repeatedly alternate, along the direction V, with radiating elements RE-L of the second array 112-2.
The antenna 100 may also include high-band (or mid-band) radiating elements RE-H. The high band (or mid band) may, in some embodiments, include frequencies that are at least twice as high as those of the low band. As noted above, the low band may comprise frequencies between 617 MHz and 960 MHz or a portion thereof, and the high band (or mid band) may comprise frequencies between 1427 MHz and 2690 MHz or a portion thereof. In some embodiments, the sub-arrays SUB-1 may operate in a first portion of the low band, and the sub-arrays SUB-2 may operate in a second portion of the low band that is different from (e.g., non-overlapping with) the first portion.
As shown in
Radiating elements RE-L that are in the shared column 170S, on the other hand, are not centered between a group of four radiating elements RE-H. Accordingly, the shared vertical column 170S may not overlap any of the radiating elements RE-H in the direction F. The direction F may be perpendicular to the directions H, V, which may also be perpendicular to each other.
Moreover, groups of three radiating elements RE-L may be in respective horizontal rows 120, and ones of the rows 120 that are closest to the top of the antenna 100 may include only radiating elements RE-L that are not centered between (and do not overlap in the direction F) a group of four radiating elements RE-H. For example, the antenna 100 may include ten rows 120-1 through 120-10, and center points of radiating elements RE-L that are in the same row 120 may be collinear in the direction H. Each row 120 includes at least one radiating element RE-L from each array 112-1, 112-2.
The radiating elements RE-L in the arrays 112-1, 112-2 are mounted to extend forwardly (i.e., in the direction F) from a reflector RL. In some embodiments, a plurality of metal side fences 150 may protrude, in the direction F, from a front surface RLF of the reflector RL. Each side fence 150 may provide an RF isolation wall for the antenna 100. Moreover, each row 120 may be between, in the direction H, a pair of the side fences 150. As a result, the side fences 150 may improve front-to-back isolation and cross-polarization isolation of the antenna 100. For example, side fences 150 that protrude forward in the direction F to a height of about 30 mm may provide front-to-back isolation that is better than about −20 decibels (“dB”). Also, a gap of about 42 mm in the direction V between adjacent side fences 150 may provide sufficient space for radome supports.
The antenna 100 further comprises RF ports 140, which may also be referred to herein as “connectors” or “antenna signal ports,” that are coupled (e.g., electrically connected) to the radiating elements RE-L, RE-H. For example, the radiating elements RE-L may be dual-polarized radiating elements so that the arrays 112-1, 112-2 may generate antenna beams at each of two polarizations (e.g., −45° and +45° slant polarizations), and each of the arrays 112-1, 112-2 may be coupled to a single RF port 140 per polarization. Others of the RF ports 140 may be coupled to the radiating elements RE-H (e.g., to respective vertical columns thereof).
The antenna signal ports 140 may also be coupled to respective radio signal ports of a radio. For example, the radio may be a MIMO beamforming radio for a cellular base station, and the antenna 100 and the radio may be located at (e.g., may be components of) a cellular base station. For simplicity of illustration, the radio and the RF connections between the radio and the antenna signal ports 140 are omitted from view in
Moreover, though the example antenna 100 has two arrays 112 of fifteen radiating elements RE-L each, antennas according to the present invention may, in some embodiments, include more or fewer radiating elements RE-L (e.g., more or fewer sub-arrays SUB) in each array 112. The number of radiating elements RE-L per array 112 may, for example, be selected so that antenna beams generated by the arrays 112 may have suitable beamwidths in the elevation (vertical) plane.
In some embodiments, each sub-array SUB may include three radiating elements RE-L. For example,
As is further shown in
In some embodiments, the horizontal fences 160 and the side fences 150 (
Moreover, a width W2 of a middle portion of the reflector RL may be equal to a pitch (e.g., a center-to-center distance) between adjacent inner columns of a conventional, non-interleaved four-column antenna. For example, the width W2 may be 230 mm. To narrow a beamwidth of the antenna 100 (e.g., to 45°), adjacent columns 170 may, in some embodiments, have a slightly larger pitch than 230 mm.
Each power divider PD may be a three-way (1:3) power divider. As an example, a fifth power divider PD-5 may be coupled to the three radiating elements RE-L-1 through RE-L-3 of the sub-array SUB-1-1 via respective RF transmission lines 130-1 through 130-3, respectively. According to some embodiments, the power dividers PD may each split power evenly such that all transmission lines 130 are configured to feed the same magnitude RF signal (e.g., sub-components thereof) to the radiating elements RE-L. The transmission lines 130 may comprise, for example, respective cables/wires, such as respective coaxial cables. The three low-band radiating elements RE-L of each sub-array SUB may be mounted on respective feed board printed circuit boards that are mounted on the front (i.e., forward) surface RLF of the reflector RL. The power dividers PD may be implemented on the feed board printed circuit boards in some embodiments.
In some embodiments, each array 112 may be coupled to a single phase shifter PS per polarization. For example,
According to some embodiments, each low-band radiating element RE-L of a sub-array SUB may be configured to have a different respective fixed phase delay applied thereto (e.g., applied to a respective RF signal sub-component fed thereto). As an example, the three radiating elements RE-L-1 through RE-L-3 of the sub-array SUB-1-1 may be configured to have fixed phase delays of 0°, 33°, and 14°, respectively, applied thereto. Accordingly, the radiating element RE-L-3, which is in the inner column 170-2 (
Moreover, the three radiating elements RE-L-4 through RE-L-6 of the sub-array SUB-2-1 may be configured to have fixed phase delays of 0°, 33°, and 28°, respectively, applied thereto. Radiating elements RE-L that are in different outer columns 170-1, 170-3 (
Adding a fixed phase difference between two radiating elements RE-L (e.g., the radiating elements RE-L-1, RE-L-2) of a sub-array SUB that are in an outer column 170-1 or 170-3 may reduce quantization lobes in the elevation plane. And a phase difference between two radiating elements RE-L (e.g., the radiating elements RE-L-1, RE-L-3) of a sub-array SUB that are in the same row 120 may improve squint performance in the azimuth plane (e.g., to meet performance criteria of 3 dB and 10 dB). Moreover, RF signal sub-components provided to the radiating elements RE-L may have the same amplitude, which may improve gain. For example, respective RF signal sub-components that are fed to the six radiating elements RE-L-1 through RE-L-6 may each have a gain of 0.33 dB.
In some embodiments, different phase delays of a sub-array SUB may be implemented by using transmission lines 130 having different lengths. For example, the transmission lines 130-1 through 130-3 that couple the radiating elements RE-L-1 through RE-L-3, respectively, to the power divider PD-5 may have three different respective cable/wire lengths. As an example, the third transmission line 130-3, which is coupled to the third radiating element RE-L-3 that is in the inner column 170-2, may have a length that is longer than respective lengths of the first and second transmission lines 130-1, 130-2. Other radiating elements RE-L that are in the inner column 170-2 may, likewise, be coupled to a respective power divider PD by a transmission line 130 that is longer than the other two transmission lines 130 that couple a sub-array SUB to the power divider PD. The other two transmission lines 130 may also have different respective lengths from each other. Moreover, the power dividers PD may, according to some embodiments, provide equal phase outputs to the transmission lines 130. Different phase delays in a sub-array SUB may thus be due to varying lengths of the transmission lines 130 rather than due to outputs of the power dividers PD.
As shown in
Each radiating element RE-L may comprise, for example, a crossed-dipole radiating element that includes a first dipole radiator and a second dipole radiator that crosses/intersects the first dipole radiator. The dipole radiators each have two dipole “arms.” To implement the radiating elements RE-L as dual-polarized crossed-dipole radiating elements, the first and second dipole radiators of each radiating element RE-L may be coupled to different transmission lines 130, respectively. For example, the first dipole radiator of the radiating element RE-L-1 may be coupled to the transmission line 130-1 (
Moreover, though the two phase shifters PS-1 (
As with the antenna 100 (
The arrays 212 differ from the arrays 112 (
For simplicity of illustration, antenna signal ports 140 (
In some embodiments, a reflector RL of the antenna 200 may have the same width W1 (e.g., about 640 mm) as that of the antenna 100. The radiating elements RE-L of the arrays 212-1, 212-2 may protrude forward from a front surface RLF of the reflector RL. Moreover, the antenna 200, like the antenna 100, may include high-band radiating elements RE-H that are overlapped, in the direction F, by some of the radiating elements RE-L. For example, each outer column 270-1, 270-3 may include seven radiating elements RE-L that each overlap four radiating elements RE-H. Rows 220 of radiating elements RE-L that are closest, in the direction V, to the top of the antenna 200 may, in some embodiments, not overlap any radiating elements RE-H. As an example, the rows 220-1, 220-2 may not overlap any radiating elements RE-H.
Antennas 100, 200 (
In some embodiments, the antenna 100 may improve squint performance and/or reduce quantization lobes by distributing different amounts of fixed phase delay to different radiating elements RE-L that are in an L-shaped sub-array SUB (
In other embodiments, the antenna 200 may achieve a narrower beamwidth by providing a plurality of sub-arrays SUB-1, SUB-2 (
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202241014927 | Mar 2022 | IN | national |
