Patent Grant
11056773
The present invention generally relates to radio communications and, more particularly, to twin-beam base station antennas utilized in cellular and other communications systems.
Cellular communications systems are well known in the art. In a typical cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells,” and each cell is served by a base station. The base station may include baseband equipment, radios and base station antennas that are configured to provide two-way radio frequency (“RF”) communications with subscribers that are positioned throughout the cell. In many cases, the cell may be divided into a plurality of “sectors,” and separate base station antennas provide coverage to each of the sectors. The base station antennas are often mounted on a tower or other raised structure, with the radiation beam (“antenna beam”) that is generated by each antenna directed outwardly to serve a respective sector. Typically, a base station antenna includes one or more phase-controlled arrays of radiating elements, with the radiating elements arranged in one or more vertical columns when the antenna is mounted for use. Herein, “vertical” refers to a direction that is perpendicular relative to the plane defined by the horizon.
A common base station configuration is a “three sector” configuration in which the cell is divided into three 120° sectors in the azimuth plane, and the base station includes three base station antennas that provide coverage to the three respective sectors. The azimuth plane refers to a horizontal plane that bisects the base station antenna that is parallel to the plane defined by the horizon. In a three sector configuration, the antenna beams generated by each base station antenna typically have a Half Power Beam Width (“HPBW”) in the azimuth plane of about 65° so that the antenna beams provide good coverage throughout a 120° sector. Typically, each base station antenna will include a vertically-extending column of radiating elements that together generate an antenna beam. Each radiating element in the column may have a HPBW of approximately 65° so that the antenna beam generated by the column of radiating elements will provide coverage to a 120° sector in the azimuth plane. The base station antenna may include multiple columns of radiating elements that operate in the same or different frequency bands.
Most modern base station antennas also include remotely controlled phase shifter/power divider circuits along the RF transmission paths through the antenna that allow a phase taper to be applied to the sub-components of an RF signal that are supplied to the radiating element in an array. By adjusting the amount of phase taper applied, the resulting antenna beams may be electrically downtilted to a desired degree in the vertical or “elevation” plane. This technique may be used to adjust how far an antenna beam extends outwardly from an antenna, and hence can be used to adjust the coverage area of the base station antenna.
Sector-splitting refers to a technique where the coverage area for a base station is divided into more than three sectors in the azimuth plane, such as six, nine or even twelve sectors. A six-sector base station will have six 60° sectors in the azimuth plane. Splitting each 120° sector into two sub-sectors increases system capacity because each antenna beam provides coverage to a smaller area, and therefore can provide higher antenna gain and/or allow for frequency reuse within a 120° sector. In six-sector sector-splitting applications, a single twin-beam antenna is typically used for each 120° sector. The twin-beam antenna generates two separate antenna beams that each have a reduced size in the azimuth plane and that each point in different directions in the azimuth plane, thereby splitting the sector into two smaller sub-sectors. The antenna beams generated by a twin-beam antenna used in a six-sector configuration preferably have azimuth HPBW values of, for example, between about 27°-39°, and the pointing directions for the first and sector sector-splitting antenna beams in the azimuth plane are typically at about −27° and about 27°, respectively.
Several approaches have been used to implement twin-beam antennas that provide coverage to respective first and second sub-sectors of a 120° sector in the azimuth plane. In a first approach, first and second columns of radiating elements are mounted on the two major interior faces of a V-shaped reflector. The angle defined by the interior surface of the “V” shaped reflector may be about 54° so that the two columns of radiating elements are mechanically positioned or “steered” to point at azimuth angles of about −27° and 27°, respectively (i.e., toward the middle of the respective sub-sectors). Since the azimuth HPBW of typical radiating elements is usually appropriate for covering a full 120° sector, an RF lens is mounted in front of the two columns of radiating elements that narrows the azimuth HPBW of each antenna beam by a suitable amount for providing coverage to a 60° sub-sector. Unfortunately, however, the use of RF lenses may increase the size, weight and cost of the base station antenna, and the amount that the RF lens narrows the beamwidth is a function of frequency, making it difficult to obtain suitable coverage when wideband radiating elements are used that operate over a wide frequency range (e.g., radiating elements that operate over the full 1.7-2.7 GHz cellular frequency range).
In a second approach, two or more columns of radiating elements (typically 2-4 columns) are mounted on a flat reflector so that each column points toward the boresight pointing direction for the antenna (i.e., the azimuth boresight pointing direction of a base station antenna refers to a horizontal axis extending from the base station antenna to the center, in the azimuth plane, of the sector served by the base station antenna). Two RF ports (per polarization) are coupled to all of the columns of radiating elements through a beamforming network such as a Butler Matrix. The beamforming network generates two separate antenna beams (per polarization) based on the RF signals input at the two RF ports, and the antenna beams are electrically steered off the boresight pointing direction of the antenna at azimuth angles of about −27° and 27° to provide coverage to the two sub-sectors. With such beamforming network based twin-beam antennas, the pointing angle in the azimuth plane of each antenna beam and the HPBW of each antenna beam may vary as a function of the frequency of the RF signals input at the two RF ports. In particular, the azimuth pointing direction of the antenna beams (i.e., the azimuth angle where peak gain occurs) tends to move toward the boresight pointing direction of the antenna and the azimuth HPBW tends to get smaller with increasing frequency. This can lead to a large variation as a function of frequency in the power level of the antenna beam at the outside edges of the sub-sectors, which is undesirable.
In a third approach, a multi-column array of radiating elements (typically three columns per array) is mounted on each exterior panel of a V-shaped reflector to provide a sector-splitting twin-beam antenna. The antenna beams generated by each multi-column array may vary less as a function of frequency as compared to the lensed and beamforming based twin beam antennas discussed above. Unfortunately, such sector-splitting antennas may require a large number of radiating elements, which increases the cost and weight of the antenna. Additionally, the inclusion of six columns of radiating elements may increase the required width for the antenna and the V-shaped reflector may increase the depth of the antenna, both of which may be undesirable.
Generally speaking, cellular operators desire twin-beam antennas that have azimuth HPBW values of anywhere between 30°-38°, so long as the azimuth HPBW does not vary significantly (e.g., more than 12°) across the operating frequency band. Likewise, the azimuth pointing angle of the antenna beam peak may vary anywhere between +/−26° to +/−33°, so long as the azimuth pointing angle does not vary significantly (e.g., more than 4°) across the operating frequency band. The peak azimuth sidelobe levels should be at least 15 dB below the peak gain value.
Pursuant to embodiments of the present invention, twin-beam base station antennas are provided that include an angled reflector having a first planar panel and a second planar panel that is angled with respect to the first planar panel, as well as first and second arrays. The first array includes a first plurality of radiating elements that extend forwardly from the first planar panel, where the radiating elements extend in three vertically-extending columns, and the radiating elements in the middle of the three vertically-extending columns are vertically offset from the radiating elements in the other two of the three vertically-extending columns. The second array includes a second plurality of radiating elements that extend forwardly from the second planar panel, where the radiating elements extend in three vertically-extending columns, and the radiating elements in the middle of the three vertically-extending columns are vertically offset from the radiating elements in the other two of the three vertically-extending columns. The antenna further includes first and second phase shifters that have inputs and respective pluralities of first and second phase shifter outputs. More than half of the first phase shifter outputs are connected to respective ones of a plurality of first sub-arrays, where each first sub-array includes a total of one radiating element from each of the three columns in the first array, and more than half of the second phase shifter outputs are connected to respective ones of a plurality of second sub-arrays, where each second sub-array includes a total of one radiating element from each of the three columns in the second array.
In some embodiments, the three radiating elements included in each first sub-array may be arranged to define a triangle, and the three radiating elements included in each second sub-array may likewise be arranged to define a triangle.
In some embodiments, the three radiating elements included in each first sub-array may be mounted on a common feed board printed circuit board that includes a pair of 1×3 power dividers, and the three radiating elements included in each second sub-array may be mounted on a common feed board printed circuit board that includes a pair of the 1×3 power dividers.
In some embodiments, the three radiating elements included in each first sub-array may include radiating elements in the outer columns that are horizontally aligned with each other, and a radiating element in the middle column that is vertically offset from the radiating elements in the outer columns.
In some embodiments, the outer columns in the first array and the outer columns in the second array may be separated in the horizontal direction by between 0.5λ and 0.95λ, where λ is the wavelength corresponding to the center frequency of the operating frequency bands of the first and second arrays.
In some embodiments, the radiating elements in the middle column of the first array may be offset in the vertical direction by between 0.6λ and 0.9λ from the closest radiating elements in the outer columns in the first array, and the radiating elements in the middle column of the second array may be offset in the vertical direction by between 0.6λ and 0.9λ from the closest radiating elements in the outer columns in the second array where λ is the wavelength corresponding to the center frequency of the operating frequency bands of the first and second arrays.
In some embodiments, each radiating element may be configured to operate in at least a portion of the 1.695 MHz to 2.690 MHz frequency band.
In some embodiments, the 1×3 power dividers may be unequal power dividers and may provide a larger amount of power to radiating elements in the middle column than to the radiating elements in the out columns.
In some embodiments, one of the first phase shifter outputs may be connected to a third sub-array that includes a total of one radiating element from each of the outer columns in the first array, and one of the second phase shifter outputs may be connected to a fourth sub-array that includes a total of one radiating element from each of the outer columns in the second array.
In some embodiments, the first array may include an equal number of first sub-arrays both above and below the third sub-array, and the second array may similarly include an equal number of second sub-arrays both above and below the fourth sub-array.
In some embodiments, the first array and the second array may each include a total of either twenty or twenty one radiating elements.
In some embodiments, each first sub-array may include a V-shaped feedboard or a triangular shaped feedboard.
Pursuant to further embodiments of the present invention, twin-beam base station antennas are provided that include an angled reflector having a first planar panel and a second planar panel that is angled with respect to the first planar panel, as well as first and second arrays. The first array includes a first plurality of radiating elements that extend forwardly from the first planar panel, where the radiating elements extend in three vertically-extending columns, and the radiating elements in the middle of the three vertically-extending columns are vertically offset from the radiating elements in the other two of the three vertically-extending columns. The second array includes a second plurality of radiating elements that extend forwardly from the second planar panel, where the radiating elements extend in three vertically-extending columns, and the radiating elements in the middle of the three vertically-extending columns are vertically offset from the radiating elements in the other two of the three vertically-extending columns. The first and third columns in the first array and the first and third columns in the second array are separated by between 0.5λ and 0.95λ, where λ is the wavelength corresponding to the center frequency of the operating frequency bands of the first and second arrays. The radiating elements in the second column of the first array are offset in the vertical direction by between 0.6λ and 0.9λ from the closest radiating elements in the first and third columns in the first array, and the radiating elements in the second column of the second array are offset in the vertical direction by between 0.6λ and 0.9λ from the closest radiating elements in the first and third columns in the second array.
In some embodiments, all or all but one of the first phase shifter outputs may be connected to respective ones of a plurality of first sub-arrays, where each first sub-array includes a total of one radiating element from each of the three columns in the first array, and all or all but one of the second phase shifter outputs may be connected to respective ones of a plurality of second sub-arrays, where each second sub-array includes a total of one radiating element from each of the three columns in the second array.
In some embodiments, the three radiating elements included in each first and second sub-array may arranged to define a triangle.
In some embodiments, the three radiating elements included in each first sub-array and in each second sub-array may be mounted on a common feed board printed circuit board that includes a pair of 1×3 power dividers. In some embodiments, the 1×3 power dividers may be unequal power dividers and provide a larger amount of power to radiating elements in the middle column than to the radiating elements in the outer columns.
In some embodiments, one of the first phase shifter outputs may be connected to a third sub-array that includes a total of one radiating element from each of the outer columns in the first array, and one of the second phase shifter outputs may be connected to a fourth sub-array that includes a total of one radiating element from each of the outer columns in the second array.
In some embodiments, the first array may include an equal number of first sub-arrays both above and below the third sub-array, and the second array may include an equal number of second sub-arrays both above and below the fourth sub-array.
In some embodiments, the first array and the second array may each include a total of either twenty or twenty one radiating elements.
A base station antenna, according to some embodiments of the present invention, may include a reflector having first and second tilted portions and a recessed flat middle portion that is between, and recessed relative to respective adjacent ends of, the first and second tilted portions. The base station antenna may include a vertical column of low-band radiating elements on the recessed flat middle portion of the reflector. The base station antenna may include a first plurality of vertical columns of high-band radiating elements on the first tilted portion of the reflector. Moreover, the base station antenna may include a second plurality of vertical columns of high-band radiating elements on the second tilted portion of the reflector.
In some embodiments, the recessed flat middle portion of the reflector may be recessed relative to the respective adjacent ends of the first and second tilted portions of the reflector by 20-40 millimeters. Moreover, the base station antenna may include a radome, and the first and second tilted portions of the reflector may slope toward each other in a forward direction toward a front side of the radome.
According to some embodiments, the first plurality of vertical columns of high-band radiating elements may include consecutive first, second, and third vertical columns of high-band radiating elements, and the second plurality of vertical columns of high-band radiating elements may include consecutive fourth, fifth, and sixth vertical columns of high-band radiating elements. The second vertical column of high-band radiating elements may be vertically staggered relative to the first and third vertical columns of high-band radiating elements, and the fifth vertical column of high-band radiating elements may be vertically staggered relative to the fourth and sixth vertical columns of high-band radiating elements. In some embodiments, the second vertical column of high-band radiating elements may be aligned in a horizontal direction with the fourth and sixth vertical columns of high-band radiating elements, and the fifth vertical column of high-band radiating elements may be aligned in the horizontal direction with the first and third vertical columns of high-band radiating elements. Moreover, respective center points of the low-band radiating elements may not be aligned in the horizontal direction with respective center points of any of the high-band radiating elements.
In some embodiments, an innermost one of the first plurality of vertical columns of high-band radiating elements may be vertically staggered relative to an innermost one of the second plurality of vertical columns of high-band radiating elements.
A base station antenna, according to some embodiments of the present invention, may include a reflector having first and second tilted portions and a flat middle portion that is between the first and second tilted portions. The base station antenna may include a vertical column of low-band radiating elements on the flat middle portion of the reflector. The base station antenna may include a first vertically-staggered plurality of vertical columns of high-band radiating elements on the first tilted portion of the reflector. The base station antenna may include a second vertically-staggered plurality of vertical columns of high-band radiating elements on the second tilted portion of the reflector. An innermost one of the first vertically-staggered plurality of vertical columns may be vertically staggered relative to an innermost one of the second vertically-staggered plurality of vertical columns.
In some embodiments, the base station antenna may include a third vertically-staggered plurality of vertical columns of high-band radiating elements on the flat middle portion of the reflector. The first vertically-staggered plurality of vertical columns may include consecutive first and second vertical columns of high-band radiating elements. The third vertically-staggered plurality of vertical columns may include consecutive third and fourth vertical columns of high-band radiating elements. The second vertically-staggered plurality of vertical columns may include consecutive fifth and sixth vertical columns of high-band radiating elements. Moreover, the first vertical column of high-band radiating elements may be aligned in a horizontal direction with the third and fifth vertical columns of high-band radiating elements, and the second vertical column of high-band radiating elements may be aligned in the horizontal direction with the fourth and sixth vertical columns of high-band radiating elements.
According to some embodiments, the flat middle portion of the reflector may be recessed relative to respective ends of the first and second tilted portions of the reflector that are adjacent the flat middle portion.
In some embodiments, the vertical column of low-band radiating elements may be a first vertical column of low-band radiating elements, and the base station may include a second vertical column of low-band radiating elements on the flat middle portion of the reflector and vertically staggered relative to the first vertical column of low-band radiating elements.
A base station antenna, according to some embodiments of the present invention, may include first and second reflector surfaces that are tilted relative to each other. The base station antenna may include a first vertical column of low-band radiating elements on the first reflector surface. The base station antenna may include a second vertical column of low-band radiating elements on the second reflector surface. The base station antenna may include a first vertically-staggered plurality of vertical columns of high-band radiating elements on the first reflector surface. Moreover, the base station antenna may include a second vertically-staggered plurality of vertical columns of high-band radiating elements on the second reflector surface.
In some embodiments, the base station antenna may include a recessed flat middle reflector surface that is between, and recessed relative to respective adjacent ends of, the first and second reflector surfaces. The first vertically-staggered plurality of vertical columns may include consecutive first, second, and third vertical columns of high-band radiating elements. The second vertically-staggered plurality of vertical columns may include consecutive fourth, fifth, and sixth vertical columns of high-band radiating elements. Moreover, the base station antenna may include a seventh vertical column of high-band radiating elements on the recessed flat middle reflector surface.
According to some embodiments, the first vertical column of low-band radiating elements may be aligned in a vertical direction with the second vertical column of high-band radiating elements, and the second vertical column of low-band radiating elements may be aligned in the vertical direction with the fifth vertical column of high-band radiating elements.
In some embodiments, the base station antenna may include third and fourth vertical columns of low-band radiating elements on the first and second reflector surfaces, respectively. The third vertical column of low-band radiating elements may be vertically staggered relative to the first vertical column of low-band radiating elements, and the fourth vertical column of low-band radiating elements may be vertically staggered relative to the second vertical column of low-band radiating elements. Moreover, the first vertical column of low-band radiating elements may be aligned in a vertical direction with the second vertical column of high-band radiating elements, the third vertical column of low-band radiating elements may be aligned in the vertical direction with the third vertical column of high-band radiating elements, the second vertical column of low-band radiating elements may be aligned in the vertical direction with the fourth vertical column of high-band radiating elements, and the fourth vertical column of low-band radiating elements may be aligned in the vertical direction with the fifth vertical column of high-band radiating elements.
According to some embodiments, the second vertical column of high-band radiating elements may include consecutive first through fourth high-band radiating elements. The first and second high-band radiating elements may be spaced apart from each other in a vertical direction by a first distance. Moreover, the second and third high-band radiating elements may be spaced apart from each other in the vertical direction by a second distance that is twice the first distance, and the third and fourth high-band radiating elements may be spaced apart from each other in the vertical direction by a third distance that is triple the first distance.
Pursuant to embodiments of the present invention, improved twin-beam base station antennas are provided that overcome or mitigate various of the difficulties with conventional twin-beam antennas. The twin-beam antennas according to embodiments of the present invention may include thinned three column arrays of radiating elements where most or all of the radiating elements are fed as triangular sub-arrays. The twin-beam base station antennas according to embodiments of the present invention may include only about two-thirds as many radiating elements as comparable conventional twin-beam antennas while achieving comparable performance.
Before discussing the twin-beam base station antennas according to embodiments of the present invention, it is helpful to examine a variety of potential twin-beam antenna designs.
Most conventional single-beam base station antennas include one or more vertically-oriented columns of dual-polarized radiating elements. Each dual-polarized radiating element in one of these arrays includes a first polarization radiator and a second polarization radiator. The most commonly used dual-polarized radiating element are cross-dipole radiating elements that include a slant −45° dipole radiator and a slant +45° degree dipole radiator. The slant −45° dipole radiator of each cross-dipole radiating element in a column is coupled to a first (−45°) RF port, and the +45° dipole radiator of each cross-dipole radiating element in the column is coupled to a second (+45°) RF port. Such a column of cross-dipole radiating elements will generate a first −45° polarization antenna beam in response to RF signals input at the first RF port, and will generate a second +45° polarization antenna beam in response to RF signals input at the second RF port. In the description below, each base station antenna is described as having slant −45°/+45° cross-dipole radiating elements for convenience and ease of comparison. It will be appreciated, however, that any appropriate radiating elements may be used including, for example, single polarization dipole radiating elements or patch radiating elements, in other embodiments
As noted above, most cross-dipole radiating elements are designed to have a half-power azimuth beamwidth (“HPBW”) of about 65°. Consequently, a column of conventional cross-dipole radiating elements will generate antenna beams having an azimuth HPBW of about 65°, which is about twice as wide as is appropriate for a twin beam antenna. This can be seen with reference to
In particular,
As shown in
The reflector 102 is V-shaped (see
The base station antenna 100 is compact and relatively inexpensive since it does not include a large number of radiating elements 122. Unfortunately, however, it is not suitable for use as a twin-beam antenna because the radiating elements 122 each generate antenna beams having an azimuth HPBW of about 65°. As shown in
A known technique for narrowing the width of an antenna beam in the azimuth plane is to transmit the RF signal that generates the antenna beam through two spaced apart vertically-extending columns of radiating elements.
Another issue with the base station antenna 200 is the elevation HPBW. The elevation HPBW for the antenna beams generated by an array that includes one or more columns of radiating elements is determined by the vertical spacing between the top and bottom radiating elements in the columns. As the vertical spacing is increased, the elevation HPBW is reduced. There are two constraints, however, on the vertical spacing. First, the vertical distance between the radiating elements in a given column of the array should be spaced apart by between about 0.6λ and 0.8λ. If the radiating elements are spaced farther apart, the elevation sidelobes tend to get larger in the exact same manner that the azimuth sidelobes get larger as the columns of radiating elements are spaced farther apart horizontally. Thus, generally speaking, to increase the vertical spacing between the top and bottom radiating elements in the columns generally requires adding additional radiating elements, which increase the cost and weight of the antenna, or accepting higher elevation sidelobe levels. Second, base station antenna manufacturers typically only manufacture a few different types of phase shifter/power divider circuits, and these circuits only have a limited number of outputs (e.g., 3-7 outputs) in order to reduce the size thereof.
As shown in
By connecting two radiating elements per column to each output of a phase shifter/power divider circuits, the number of radiating elements in each column may be increased to, for example, ten radiating elements (for a 1×5 phase shifter/power divider circuit) or to fourteen radiating elements (for a 1×7 phase shifter/power divider circuit). With this increase in the number of radiating elements per column, the elevation beamwidth can be narrowed to a suitable degree. However, even with ten radiating elements, it is necessary to space the radiating elements fairly far apart in the vertical direction to achieve desired elevation HPBW values (which are typically much smaller than the azimuth HPBW values).
In particular,
As noted above, the high azimuth sidelobes exhibited by the base station antennas 200 and 300 can be attributed to the large spacing between adjacent radiating elements 122 in the horizontal direction, which is necessary to achieve sufficient narrowing of the azimuth HPBW.
By offsetting the center columns 520-2, 520-5 from the remaining columns 520, the spacing between adjacent radiating elements is increased. As shown in
Pursuant to embodiments of the present invention, improved twin-beam base station antennas are provided that include first and second arrays of radiating elements that may be mounted on the respective first and second major panels of a generally V-shaped reflector. Each array includes three vertically-extending columns of radiating elements. The center column in each array is vertically offset from the outer columns in the array. The arrays are “thinned” in the vertical direction as compared to the prior art base station 500 of
The base station antennas according to embodiments of the present invention may include substantially fewer radiating elements as compared to the state-of-the-art twin-beam base station antenna 500 of
As shown in
As shown in
As is further shown in
Referring to
Simulations have been performed to analyze various performance parameters for the twin-beam base station antenna 600 of
As shown in TABLE I, the mean azimuth HPBW for each antenna beam generated by the base station antenna 600 is between 38° and 29°, with a variance of less than 4° within all five sub-bands. The 12 dB azimuth beamwidths, which range from 73°-55° are acceptable, and the azimuth pointing angle can be selected to be any desired value and will be the same across all sub-bands since the azimuth pointing angle is determined by the mechanical steering of the reflector. While not listed in TABLE I, the peak azimuth sidelobes are more than 15 dB below the peak gain across all sub-bands. The elevation sidelobes exceed −15 dB (see
The high-band array 1010-1 may include a first plurality of vertical columns 1020 of high-band radiating elements 122, and the high-band array 1010-2 may include a second plurality of vertical columns 1020 of high-band radiating elements 122. For example, the array 1010-1 may include three high-band vertical columns 1020-1, 1020-2, and 1020-3, and the array 1010-2 may include another three high-band vertical columns 1020-4, 1020-5, and 1020-6. Moreover, the low-band array 1030 may be a single vertical column of low-band radiating elements 1021. In some embodiments, the term “high-band” refers to a frequency band including 1695-2690 MHz or a portion thereof, and the term “low-band” refers to a frequency band including 694-960 MHz or a portion thereof.
The recessed flat middle portion 104-RM has a depth D that is spaced apart, in the forward direction F, from the horizontal plane HP. For example, the depth D may be 20-40 mm. Moreover, the tilted portions 104-1 and 104-2 have respective ends (e.g., end points) 104-1E and 104-2E that are adjacent each other and are in, or nearly in, the horizontal plane HP. Accordingly, the recessed flat middle portion 104-RM may be recessed relative to the ends 104-1E and 104-2E by approximately 20-40 mm. As shown in
By integrating low-band radiating elements 1021 with high-band radiating elements 122 on the reflector 102R (or 102), the antenna 1000R (or 1000) may provide an azimuth beamwidth (e.g., HPBW) of, for example, about 65° in a low frequency band, in addition to a twin-beam azimuth beamwidth (e.g., HPBW) of about 33° in a high frequency band. Moreover, the reflector 102R (or 102) may be tilted and shaped to improve beam-to-beam isolation for the twin-beam layout. For example, the tilt of the tilted portions 104-1 and 104-2, as well as the increased spacing between the tilted portions 104-1 and 104-2 due to the recessed flat middle portion 104-RM (or the flat middle portion 104-M), can reduce coupling between the high-band arrays 1010-1 and 1010-2.
In some embodiments, the high-band arrays 1010-1 and 1010-2 may each have triangular sub-arrays mounted on the reflector 102R (or 102). Such triangular arrangements of high-band radiating elements 122 can reduce costs by using fewer radiating elements 122 than conventional arrangements, and can decrease coupling between radiating elements 122 and improve space utilization in the antenna 1000R (or 1000).
For example, consecutive ones of the high-band vertical columns 1020-1, 1020-2, and 1020-3 may be vertically staggered relative to each other, and consecutive ones of the high-band vertical columns 1020-4, 1020-5, and 1020-6 may be vertically staggered relative to each other. Accordingly, the high-band vertical column 1020-2 may be vertically staggered relative to the high-band vertical columns 1020-1 and 1020-3, and the high-band vertical column 1020-5 may be vertically staggered relative to the high-band vertical columns 1020-4 and 1020-6.
Moreover, the array 1010-1 (
Each high-band radiating element 122 may have a respective center point 122C (
In particular, the antenna 1100 may have a first high-band array 1110-1 that includes a first plurality of vertical columns 1120 of radiating elements 122L on the tilted portion 104-1, and a second high-band array 1110-2 that includes a second plurality of vertical columns 1120 of radiating elements 122L on the tilted portion 104-2. Each radiating element 122L may be a low-cost, sheet-metal dipole. Moreover, the antenna 1100 may have a low-band array 1130, which may be a vertical column of radiating elements 1021L on the recessed flat middle portion 104-RM, and each radiating element 1021L may be a low-cost, sheet-metal dipole. By using sheet metal on, for example, a plastic frame, a low-cost and relatively-compact dipole may be provided. As the size of the radiating elements 122L, and/or the size of the radiating elements 1021L, decreases, mutual coupling may also decrease, thus resulting in improved RF performance of the antenna 1100.
To achieve an azimuth beamwidth of about 33° in a high frequency band, the regions 1210-1, 1210-2, and 1210-M may collectively provide two three-column high-band arrays. For example, a first high-band array may include the vertical columns 1220-1, 1220-2, and 1220-3, and a second high-band array may include the vertical columns 1220-4, 1220-5, and 1220-6. In each of the high-band arrays, one of the vertical columns 1220 (e.g., in the region 1210-M) may not be tilted, but rather may have an adjusted phase.
In some embodiments, a low-band vertical column 1230 may be on the flat middle portion 104-M between the vertical columns 1220-3 and 1220-4. Accordingly, high-band radiating elements 122 and low-band radiating elements 1021 may be on the same flat surface of the reflector 102. By adjusting the phase at radiating elements 122 on the flat middle portion 104-M, twin-beam performance with a beamwidth of about 33° in a high frequency band can be improved. Moreover, to accommodate the combination of radiating elements 122 and radiating elements 1021, the flat middle portion 104-M may be relatively wide in the horizontal direction H, thus allowing radiating elements 1021 to “see” more of the reflector 102. For example, the flat middle portion 104-M may be approximately equal in width to each of the tilted portions 104-1 and 104-2. Because it has a single reflector 102 for all radiating elements 122 and 1021, the antenna 1200 may also be easier to manufacture than an antenna that has high-band radiating elements and low-band radiating elements on separate reflectors.
In contrast with the antenna 1200, however, the antenna 1300 may include a first vertical column 1330-1 of low-band radiating elements 1021 and a second vertical column 1330-2 of low-band radiating elements 1021 that is vertically staggered relative to the first vertical column 1330-1. The vertical columns 1330-1 and 1330-2 may both be on the flat middle portion 104-M. The vertical columns 1330-1 and 1330-2 may be part of the same low-band array, and the radiating elements 1021 may be staggered among the different vertical columns 1330-1 and 1330-2 to decrease the azimuth beamwidth of the low-band array.
A first high-band array 1410-1 of the antenna 1400 may include vertical columns 1420-1, 1420-2, and 1420-3 on the tilted portion 104-1, and a second high-band array 1410-2 of the antenna 1400 may include vertical columns 1420-4, 1420-5, and 1420-6 on the tilted portion 104-2. A first low-band region 1430-1 may also be on the tilted portion 104-1, and a second low-band region 1430-2 may also be on the tilted portion 104-2. Moreover, though
The recessed flat middle portion 104-RM may be a flat surface that is recessed relative to respective adjacent ends 104-1E and 104-2E of the tilted portions 104-1 and 104-2. Accordingly, the recessed flat middle portion 104-RM may be referred to herein as a “recessed flat middle reflector surface.” To provide separation between the low-band arrays 1530-1 and 1530-2, the recessed flat middle portion 104-RM may include only high-band radiating elements 122 (i.e., no low-band radiating elements 1021). Moreover, to reduce coupling due to the high-band array 1510-M, a width W of the antenna 1500 may, in some embodiments, be wider than that of the antennas 1000 (
Consecutive ones of the vertical columns 1520-1, 1520-2, and 1520-3 may be vertically staggered. Accordingly, the vertical column 1520-2 may be vertically staggered relative to both of the vertical columns 1520-1 and 1520-3. Similarly, consecutive ones of the vertical columns 1520-5, 1520-6, and 1520-7 may be vertically staggered.
As shown in
It will be appreciated that the present specification only describes a few example embodiments of the present invention and that the techniques described herein have applicability beyond the example embodiments described above.
The description above primarily describes the transmit paths through the base station antennas described herein. It will be appreciated that base station antennas include bi-directional RF signal paths, and that the base station antennas will also be used to receive RF signals. In the receive path, RF signals will typically be combined whereas the RF signals are split in the transmit path. Thus, it will be apparent to the skilled artisan that the base station antennas described herein may be used to receive RF signals.
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.).
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 |
|---|---|---|---|
| 201921025801 | Jun 2019 | IN | national |
The present application claims priority to Indian Application Serial No. 201921025801, filed Jun. 28, 2019 and to U.S. Provisional Application Ser. No. 62/935,663, filed Nov. 15, 2019, the entire content of each of which is incorporated herein by reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20200411961 A1 | Dec 2020 | US |
| Number | Date | Country | |
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| 62935663 | Nov 2019 | US |
