CN112151943A - Dual-beam base station antenna with sparse array with triangular sub-arrays - Google Patents

Abstract

The invention relates to a dual beam base station antenna with a sparse array with triangular sub-arrays. The dual beam base station antenna includes first and second arrays, each array having a plurality of radiating elements mounted to extend forwardly from respective first and second panels of the angled reflector. The radiating elements in each array extend in three columns, with the radiating elements in the middle column being vertically offset from the radiating elements in the outer columns. The antenna also includes a first phase shifter and a second phase shifter. More than half of the outputs of the first phase shifters are connected to a respective first sub-array, wherein each first sub-array comprises one radiating element from each of the three columns in the first array, and more than half of the outputs of the second phase shifters are connected to a respective second sub-array, wherein each second sub-array comprises one radiating element from each of the three columns in the second array.

Description

Dual-beam base station antenna with sparse array with triangular sub-arrays

Cross Reference to Related Applications

This application claims priority to indian application serial No.201921025801 filed on 28.6.2019 and U.S. provisional application serial No.62/935,663 filed on 15.11.2019, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates generally to radio communications, and more particularly to dual beam base station antennas for use in cellular and other communication systems.

Background

Cellular communication systems are well known in the art. In a typical cellular communication system, a geographic area is divided into a series of areas called "cells," and each cell is served by a base station. The base station may include base band equipment, radios and base station antennas configured to provide two-way radio frequency ("RF") communication with subscribers located throughout the cell. In many cases, a cell may be divided into multiple "sectors," and separate base station antennas provide coverage for each sector. The base station antennas are often mounted on towers or other raised structures with the radiation beam ("antenna beam") generated by each antenna directed outward to serve a corresponding sector. Typically, a base station antenna comprises a phased array of one or more radiating elements arranged in one or more vertical columns when the antenna is mounted for use. In this context, "vertical" refers to a direction perpendicular with respect to a 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 for the three respective sectors. The azimuth plane refers to a horizontal plane parallel to a plane defined by the horizon that bisects the base station antenna. In a three sector configuration, the antenna beam generated by each base station antenna typically has a half power beamwidth ("HPBW") of about 65 ° in the azimuth plane, so that the antenna beam provides good coverage throughout the 120 ° sector. Typically, each base station antenna will comprise a vertically extending column of radiating elements which together generate an antenna beam. Each radiating element in a column may have an HPBW of approximately 65 ° so that the antenna beam generated by the column of radiating elements will provide coverage for a 120 ° sector in the azimuth plane. The base station antenna may include multiple columns of radiating elements operating 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 path through the antenna that allow phase tapers to be applied to the subcomponents of the RF signals supplied to the radiating elements in the array. By adjusting the amount of phase taper applied, the resulting antenna beam can be electrically downtilted to a desired degree in the vertical or "elevation" plane. This technique can be used to adjust how far the antenna beam extends outward from the antenna and thus can be used to adjust the coverage area of the base station antenna.

Sector splitting refers to a technique in which the coverage area of a base station is divided into more than three sectors, such as six, nine, or even twelve sectors, in the azimuth plane. 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 for a smaller area, and thus may provide higher antenna gain and/or allow frequency reuse within the 120 sector. In a six sector splitting application, a single dual beam antenna is typically used for each 120 sector. The dual beam antenna generates two separate antenna beams, each antenna beam having a reduced size in the azimuth plane and each antenna beam pointing in a different direction in the azimuth plane, thereby splitting the sector into two smaller sub-sectors. The antenna beams generated by the dual-beam antenna used in the six-sector configuration preferably have azimuth HPBW values of, for example, between about 27 ° -39 °, and the pointing directions of the first and second sector split antenna beams in the azimuth plane are typically at about-27 ° and about 27 °, respectively.

Several approaches have been used to implement dual-beam antennas that provide coverage for respective first and second sub-sectors of a 120 sector in the azimuth plane. In a first approach, a first column of radiating elements and a second column of radiating elements are mounted on two major inner faces of a V-shaped reflector. The angle defined by the inner surface of the "V" shaped reflector may be about 54 deg., so that the two columns of radiating elements are mechanically positioned or "steered" to point at azimuth angles of about-27 deg. and 27 deg., respectively (i.e., toward the middle of the corresponding sub-sector). Since the azimuth HPBW of a typical radiating element is typically adapted to cover the entire 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 an appropriate amount to provide coverage of the 60 ° sub-sector. Unfortunately, however, the use of an RF lens increases the size, weight, and cost of the base station antenna, and the amount by which the beam width is narrowed by the RF lens is a function of frequency, so it is difficult to obtain suitable coverage when using broadband radiating elements that operate over a wide frequency range (e.g., radiating elements that operate over the entire 1.7GHz-2.7GHz cellular frequency range).

In a second approach, two or more columns of radiating elements (typically 2-4 columns) are mounted on a planar reflector such that each column points in a direction toward the boresight of the antenna (i.e., the boresight pointing direction of a base station antenna refers to the horizontal axis extending from the base station antenna to the center of the sector in the azimuth plane served by the base station antenna). Two RF ports (each polarization) are coupled to all columns of radiating elements through a beam forming network, such as a Butler matrix. The beamforming network generates two separate antenna beams (each polarization) based on RF signals input at the two RF ports, and electrically steers the antenna beams from the boresight pointing direction of the antenna at azimuth angles of about-27 ° and 27 ° to provide coverage for the two sub-sectors. With such a beam forming network based dual beam antenna, the pointing angle in the azimuth plane of each antenna beam and the HPBW of each antenna beam may vary depending on the frequency of the RF signals input at the two RF ports. In particular, the azimuth pointing direction of the antenna beam (i.e., the azimuth angle at which the peak gain occurs) tends to move toward the boresight pointing direction of the antenna, and the azimuth HPBW tends to become smaller as the frequency increases. This can result in a large variation in the power level of the antenna beam with frequency at the outer 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 outer panel of a V-shaped reflector to provide a sector-splitting dual beam antenna. The antenna beams generated by each multi-column array may vary less with frequency than the lens and beamforming based dual beam antenna discussed above. Unfortunately, such a sector-split antenna may require a large number of radiating elements, which increases the cost and weight of the antenna. Furthermore, including six columns of radiating elements may increase the width required for the antenna, and the V-shaped reflector may increase the depth of the antenna, both of which may be undesirable.

In general, cellular operators desire dual-beam antennas with azimuth HPBW values anywhere between 30 ° -38 °, as long as the azimuth HPBW does not vary significantly (e.g., greater than 12 °) throughout the operating 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., by more than 4 °) throughout the operating frequency band. The peak azimuth sidelobe level should be at least 15dB below the peak gain value.

Disclosure of Invention

According to an embodiment of the present invention, a dual beam base station antenna is provided that includes an angled reflector having a first planar panel and a second planar panel angled with respect to the first planar panel, and a first array and a second array. The first array includes a first plurality of radiating elements extending forward from the first planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns. The second array includes a second plurality of radiating elements extending forward from the second planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns. The antenna also includes first and second phase shifters having an input and a corresponding plurality of first and second phase shifter outputs. More than half of the first phase shifter outputs are connected to a respective first sub-array of the plurality of first sub-arrays, wherein each first sub-array comprises 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 a respective second sub-array of the plurality of second sub-arrays, wherein each second sub-array comprises 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 including a pair of 1 x 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 including a pair of 1 x 3 power dividers.

In some embodiments, the three radiating elements included in each first subarray may include radiating elements in outer columns that are horizontally aligned with one another, and radiating elements in intermediate columns that are vertically offset with respect to 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 0.5 λ and 0.95 λ, where λ is a wavelength corresponding to a center frequency of the operating band of the first array and the second array.

In some embodiments, the radiating elements in a middle column of the first array may be vertically offset from nearest radiating elements in outer columns of the first array by between 0.6 λ and 0.9 λ, and the radiating elements in a middle column of the second array may be vertically offset from nearest radiating elements in outer columns of the second array by between 0.6 λ and 0.9 λ, where λ is a wavelength corresponding to a center frequency of an operating band of the first and second arrays.

In some embodiments, each radiating element may be configured to operate in at least a portion of the 1.695MHz to 2.690MHz frequency band.

In some embodiments, the 1 x 3 power dividers may be unequal power dividers, and may provide a greater amount of power to the 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 comprising a total of one radiating element from each outer column in the first array, and one of the second phase shifter outputs may be connected to a fourth sub-array comprising a total of one radiating element from each outer column 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 and second arrays may each include a total of twenty or twenty-one radiating elements.

In some embodiments, each first sub-array may include a V-shaped feed plate or a triangular-shaped feed plate.

According to a further embodiment of the present invention, a dual beam base station antenna is provided that includes an angled reflector having a first planar panel and a second planar panel angled with respect to the first planar panel, and a first array and a second array. The first array includes a first plurality of radiating elements extending forward from the first planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns. The second array includes a second plurality of radiating elements extending forward from the second planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns 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 0.5 λ and 0.95 λ, where λ is a wavelength corresponding to a center frequency of the operating band of the first and second arrays. The radiating elements in the second column of the first array are offset between 0.6 λ and 0.9 λ in the vertical direction relative to the nearest radiating elements in the first and third columns of the first array, and the radiating elements in the second column of the second array are offset between 0.6 λ and 0.9 λ in the vertical direction relative to the nearest radiating elements in the first and third columns of the second array.

In some embodiments, all or all but one of the first phase shifter outputs may be connected to a respective first sub-array of a plurality of first sub-arrays, wherein each first sub-array comprises a total of one radiating element from each of three columns in the first array, and all or all but one of the second phase shifter outputs may be connected to a respective second sub-array of a plurality of second sub-arrays, wherein each second sub-array comprises a total of one radiating element from each of three columns in the second array.

In some embodiments, the three radiating elements included in each of the first and second sub-arrays may be arranged to define a triangle.

In some embodiments, the three radiating elements included in each first sub-array and each second sub-array may be mounted on a common feed board printed circuit board including a pair of 1 x 3 power dividers. In some embodiments, the 1 x 3 power dividers may be unequal power dividers, and provide a greater amount of power to the 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 comprising a total of one radiating element from each outer column in the first array, and one of the second phase shifter outputs may be connected to a fourth sub-array comprising a total of one radiating element from each outer column 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 and second arrays may each include a total of twenty or twenty-one radiating elements.

According to some embodiments of the present invention, a base station antenna may include a reflector having first and second inclined portions and a recessed flat middle portion between the first and second inclined portions and recessed with respect to respective adjacent ends of the first and second inclined portions. The base station antenna may include a vertical column of low band radiating elements on a concave flat middle portion of the reflector. The base station antenna may include a first plurality of vertical columns of high-band radiating elements on a first angled portion of the reflector. Also, the base station antenna may include a second plurality of vertical columns of high-band radiating elements on a second angled portion of the reflector.

In some embodiments, the concave flat middle portion of the reflector may be concave by 20-40 millimeters relative to the respective adjacent ends of the first and second inclined portions of the reflector. Also, the base station antenna may include a radome, and the first and second inclined portions of the reflector may be inclined toward each other in a forward direction toward a front side of the radome.

In accordance with some embodiments, the first plurality of vertical columns of high-band radiating elements may include a first, second, and third consecutive vertical column of high-band radiating elements, and the second plurality of vertical columns of high-band radiating elements may include a fourth, fifth, and sixth consecutive vertical column of high-band radiating elements. The second vertical column of high-band radiating elements may be vertically staggered with respect 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 with respect 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 horizontally aligned with the fourth and sixth vertical columns of high-band radiating elements, and the fifth vertical column of high-band radiating elements may be horizontally aligned with the first and third vertical columns of high-band radiating elements. Moreover, the respective center points of the low-band radiating elements may not be horizontally aligned with the respective center points of any of the high-band radiating elements.

In some embodiments, an innermost column of the first plurality of vertical columns of high-band radiating elements may be vertically staggered relative to an innermost column of the second plurality of vertical columns of high-band radiating elements.

According to some embodiments of the present invention, a base station antenna may include a reflector having first and second inclined portions and a flat middle portion between the first and second inclined portions. The base station antenna may include a vertical column of low band radiating elements on a flat middle portion of the reflector. The base station antenna may include a first plurality of vertically staggered vertical columns of high-band radiating elements on a first angled portion of the reflector. The base station antenna may include a second vertically staggered plurality of vertical columns of high-band radiating elements on a second angled portion of the reflector. An innermost column of the first vertically staggered plurality of vertical columns may be vertically staggered relative to an innermost column 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 interleaved plurality of vertical columns can include consecutive first and second vertical columns of high-band radiating elements. The third vertically interleaved plurality of vertical columns can include consecutive third and fourth vertical columns of high-band radiating elements. The second vertically staggered plurality of vertical columns can include consecutive fifth and sixth vertical columns of high-band radiating elements. Also, the first vertical column of high-band radiating elements may be horizontally aligned with the third vertical column and the fifth vertical column of high-band radiating elements, and the second vertical column of high-band radiating elements may be horizontally aligned with the fourth vertical column and the sixth vertical column of high-band radiating elements.

According to some embodiments, the flat middle portion of the reflector may be recessed with respect to respective ends of the first and second inclined portions of the reflector adjacent to 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 antenna may include a second vertical column of low band radiating elements vertically staggered on the flat middle portion of the reflector and relative to the first vertical column of low band radiating elements.

According to some embodiments of the invention, the base station antenna may comprise a first reflector surface and a second reflector surface inclined with respect to each other. The base station antenna may include a first vertical column of low band radiating elements on a 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. Also, 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 concave flat intermediate reflector surface between the first reflector surface and the second reflector surface and concave relative to respective adjacent ends of the first reflector surface and the second reflector surface. The first vertically staggered plurality of vertical columns can include consecutive first, second, and third vertical columns of high-band radiating elements. The second vertically staggered plurality of vertical columns can include consecutive fourth, fifth, and sixth vertical columns of high-band radiating elements. Also, the base station antenna may include a seventh vertical column of high-band radiating elements on the concave flat intermediate reflector surface.

In accordance with some embodiments, the first vertical column of low-band radiating elements may be vertically aligned with the second vertical column of high-band radiating elements, and the second vertical column of low-band radiating elements may be vertically aligned with the fifth vertical column of high-band radiating elements.

In some embodiments, the base station antenna may include a third vertical column and a fourth vertical column of low-band radiating elements on the first reflector surface and the second reflector surface, respectively. The third vertical column of low-band radiating elements may be vertically staggered with respect to the first vertical column of low-band radiating elements, and the fourth vertical column of low-band radiating elements may be vertically staggered with respect to the second vertical column of low-band radiating elements. Also, the first vertical column of low-band radiating elements may be vertically aligned with the second vertical column of high-band radiating elements, the third vertical column of low-band radiating elements may be vertically aligned with the third vertical column of high-band radiating elements, the second vertical column of low-band radiating elements may be vertically aligned with the fourth vertical column of high-band radiating elements, and the fourth vertical column of low-band radiating elements may be vertically aligned 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 high-band radiating element and the second high-band radiating element may be vertically spaced apart from each other by a first distance. Also, the second high-band radiating element and the third high-band radiating element may be vertically spaced apart from each other by a second distance that is twice the first distance, and the third high-band radiating element and the fourth high-band radiating element may be vertically spaced apart from each other by a third distance that is three times the first distance.

Drawings

Figure 1A is a schematic plan view of a dual beam base station antenna with a single column of individually fed radiating elements mounted on each of the two major faces of a V-shaped reflector.

Fig. 1B is a schematic cross-sectional view of the base station antenna of fig. 1A.

Fig. 1C is a graph of the "envelope" of the azimuth pattern of the base station antenna of fig. 1A.

Figure 2A is a schematic plan view of a dual beam base station antenna having two columns of radiating elements fed as 2 x 1 sub-arrays mounted on each of the two major faces of a V-shaped reflector.

Fig. 2B is a schematic cross-sectional view of the base station antenna of fig. 2A.

Fig. 2C is a graph of an envelope of the azimuth pattern of the base station antenna of fig. 2A.

Figure 3A is a schematic plan view of a dual beam base station antenna having two columns of radiating elements fed as 2 x 2 rectangular sub-arrays mounted on each of the two major faces of a V-shaped reflector.

Fig. 3B is a schematic cross-sectional view of the base station antenna of fig. 3A.

Fig. 3C is a graph of an envelope of the azimuth pattern of the base station antenna of fig. 3A.

Fig. 3D is a graph of an envelope of the elevation pattern of the base station antenna of fig. 3A.

Figure 4A is a schematic plan view of a dual beam base station antenna having three columns of radiating elements fed as 3 x 2 rectangular sub-arrays mounted on each of the two major faces of a V-shaped reflector.

Fig. 4B is a schematic cross-sectional view of the base station antenna of fig. 4A.

Fig. 4C is a graph of an envelope of the azimuth pattern of the base station antenna of fig. 4A.

Fig. 4D is a graph of an envelope of the elevation pattern of the base station antenna of fig. 4A.

Fig. 5A is a schematic plan view of a dual beam base station antenna having three columns of radiating elements fed as 3 x 2 offset rectangular sub-arrays mounted on each of the two major faces of a V-shaped reflector.

Fig. 5B is a schematic cross-sectional view of the base station antenna of fig. 5A.

Fig. 5C is a graph of an envelope of the azimuth pattern of the base station antenna of fig. 5A.

Fig. 5D is a graph of an envelope of the elevation pattern of the base station antenna of fig. 5A.

Figure 6A is a schematic plan view of a dual beam base station antenna according to an embodiment of the present invention having three columns of radiating elements fed as 3 x 1 triangular sub-arrays mounted on each of the two major faces of a V-shaped reflector.

Fig. 6B is a schematic cross-sectional view of the base station antenna of fig. 6A.

Fig. 6C is a block diagram of the feed network of the base station antenna of fig. 6A.

Fig. 6D is a graph of an envelope of the azimuth pattern of the base station antenna of fig. 6A.

Fig. 6E is a graph of an envelope of the elevation pattern of the base station antenna of fig. 6A.

Figure 7A is a schematic plan view of a dual-beam base station antenna according to further embodiments of the present invention.

Fig. 7B is a schematic cross-sectional view of the base station antenna of fig. 7A.

Figure 8 is a schematic elevation view of a dual-beam base station antenna according to a further embodiment of the present invention.

Fig. 9A is a schematic front view of a feed plate that may be used in a base station antenna according to an embodiment of the present invention.

Fig. 9B is a schematic front view of another feed plate that may be used in a base station antenna according to an embodiment of the present invention.

Figure 10A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Figure 10B is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 10C and 10D are schematic front views of the base station antenna of fig. 10B.

Figure 11A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 11B is a schematic front view of the base station antenna of fig. 11A.

Figure 12A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 12B is a schematic front view of the base station antenna of fig. 12A.

Figure 13A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 13B is a schematic front view of the base station antenna of fig. 13A.

Figure 14A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 14B is a schematic front view of the base station antenna of fig. 14A.

Figure 15A is a cross-sectional view of a dual-beam base station antenna according to an embodiment of the present invention.

Fig. 15B and 15C are schematic front views of the base station antenna of fig. 15A.

Figure 15D is a schematic elevation view of a dual-beam base station antenna according to an embodiment of the present invention.

Detailed Description

In accordance with embodiments of the present invention, an improved dual-beam base station antenna is provided that overcomes or alleviates the various difficulties of conventional dual-beam antennas. Dual beam antennas according to embodiments of the present invention may include a sparse three column array of radiating elements, with most or all of the radiating elements being fed as triangular sub-arrays. A dual-beam base station antenna according to embodiments of the present invention may include only about two-thirds of the radiating elements as compared to a comparable conventional dual-beam antenna while achieving comparable performance.

Before discussing a dual-beam base station antenna in accordance with an embodiment of the present invention, it is helpful to examine various potential dual-beam antenna designs.

Most conventional single beam base station antennas comprise one or more vertically aligned dual polarized radiating elements. Each dual polarized radiating element in one of the arrays comprises a first polarized radiator and a second polarized radiator. The most commonly used dual polarized radiating elements are crossed dipole radiating elements, which include tilted-45 ° dipole radiators and tilted +45 ° dipole radiators. The tilted-45 dipole radiator of each cross-dipole radiating element in the 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 crossed dipole radiating elements will generate a first-45 deg. polarized antenna beam in response to an RF signal input at the first RF port and a second +45 deg. polarized antenna beam in response to an RF signal input at the second RF port. In the following description, for convenience and ease of comparison, each base station antenna is described as having a tilted-45 °/+45 ° crossed dipole radiating element. However, it should be appreciated that in other embodiments, any suitable radiating element may be used, including, for example, a single-polarized dipole radiating element or a patch radiating element.

As described above, most cross dipole radiating elements are designed to have a half power azimuth beamwidth ("HPBW") of about 65 °. Thus, one column of conventional cross dipole radiating elements will generate an antenna beam having an azimuth HPBW of about 65 °, which is about twice the width suitable for a dual beam antenna. This can be seen with reference to fig. 1A-1C.

In particular, fig. 1A is a schematic plan view of a base station antenna 100, the base station antenna 100 comprising a single column of individually fed radiating elements mounted on each of the two major faces of a V-shaped reflector 102. Fig. 1B is a schematic cross-sectional view of the base station antenna 100 of fig. 1A. Fig. 1C is a graph of the "envelope" of the azimuth pattern of the base station antenna 100. As known to those skilled in the art, the azimuth and elevation patterns of an antenna beam generated by a base station antenna are typically evaluated at a plurality of different frequencies across the operating frequency band of the radiating element used to generate the antenna beam. Herein, the "envelope" of the azimuth pattern or the elevation pattern refers to a curve representing the highest value at each frequency in the azimuth pattern and the elevation pattern. In evaluating the performance of a base station antenna, it may be simpler to look at the envelope of the azimuth and elevation patterns than many different curves representing the azimuth and elevation patterns at a number of different frequencies.

As shown in fig. 1A, the base station antenna 100 includes a longitudinally extending reflector 102 having a first column 120-1 and a second column 120-2 of radiating elements 122 mounted thereon. Herein, when multiple identical elements are included in an antenna, these elements may be individually referred to by their full reference number (e.g., column 120-2) and may be collectively referred to by a first portion of their reference number (e.g., column 120). The reflector 102 may comprise a metal sheet that serves as a ground plane for the radiating element 122 and also redirects a number of rearwardly directed radiation emitted by the radiating element 122 forwardly.

The reflector 102 is V-shaped (see fig. 1B), and thus includes a first panel 104-1 and a second panel 104-2 that are angled with respect to each other. A virtual axis a1 extending through the apex of the "V" may point approximately midway in the azimuth plane through the sector served by the base station antenna 100. The first panel 104-1 may be at an angle- α to a plane P perpendicular to the axis a1, and the second panel 104-2 may be at an angle α to the plane P. The radiating elements 122 in the first column 120-1 are mounted to extend forward from the first panel 104-1 and together form the first array 110-1. The radiating elements 122 in the second column 120-2 are mounted to extend forward from the second panel 104-2 and together form the second array 110-2. The peak radiation of the antenna beams generated by the first array 110-1 will extend outwardly along an axis a2 that is perpendicular to the first panel 104-1, and the peak radiation of the antenna beams generated by the second array 110-2 will extend outwardly along an axis A3 that is perpendicular to the second panel 104-2. The angle alpha is typically selected to be about 27 deg. -30 deg., so that the antenna beams generated by the first and second arrays 110 will be directed to approximately the middle of the respective two sub-sectors of the sector covered by the base station antenna 100.

The base station antenna 100 is compact and relatively inexpensive because it does not include a large number of radiating elements 122. Unfortunately, however, it is not suitable for use as a dual-beam antenna because the radiating elements 122 each generate an antenna beam having an azimuth HPBW of about 65 °. As shown in fig. 1C, vertically oriented columns of these radiating elements 122 (such as columns 120-1 and 120-2) will generate antenna beams having an azimuth HPBW of approximately 65 °. Such an antenna beam is not suitable for covering a 60 ° sub-sector, since nearly half of the signal energy will fall outside this sub-sector, which is not beneficial and appears as interference in neighboring sub-sectors.

A known technique for narrowing the width of an antenna beam in the azimuth plane is to transmit RF signals that generate the antenna beam through two spaced apart vertically extending columns of radiating elements. Fig. 2A and 2B schematically illustrate a base station antenna 200 having such a design. As shown in fig. 2A and 2B, the base station antenna 200 may include the same longitudinally extending V-shaped reflector 102 as discussed above with reference to fig. 1A-1B. The first array 210-1 is mounted on the first panel 104-1 and the second array 210-2 is mounted on the second panel 204-2. The first array 210-1 includes columns 220-1, 220-2 of radiating elements 122 and the second array 210-2 includes columns 220-3, 220-4 of radiating elements 122. By transmitting each RF signal through an array 210 of radiating elements 122 each comprising two side-by-side columns, the azimuth HPBW of the antenna beam can be significantly reduced, as shown in fig. 2C. The amount by which azimuth HPBW is reduced varies depending on the horizontal distance between two columns 220 in each array 210. To achieve a suitable azimuth HPBW (e.g., approximately 33 ° +/-5 ° azimuth HPBW for all frequencies in the operating band and for the entire range of electronic downtilt), the two arrays typically must be spaced quite far apart (e.g., 1 λ, where λ is the wavelength corresponding to the center frequency of the operating band of the arrays). Unfortunately, as can also be seen in fig. 2C, such wide spacing tends to increase the amplitude of the side lobes in the azimuth pattern. In general, the azimuth sidelobe levels should be at least 13dB lower than the peak gain, and preferably at least 15dB lower than the peak gain. In contrast, the azimuth sidelobe level in fig. 2C is only 7.5dB lower than the peak gain. While these side lobes can be reduced by moving the two columns 220 in each array 210 closer together, this will increase the azimuth HPBW to an unacceptably high level. Therefore, the antenna design shown in fig. 2A-2B is also not suitable for use as a dual beam base station antenna, since it will generate an antenna beam with too high azimuth side lobe levels and/or too wide azimuth HPBW.

Another problem with the base station antenna 200 is the elevation angle HPBW. The elevation angle HPBW of an antenna beam generated by an array comprising one or more columns of radiating elements is determined by the vertical spacing between the top and bottom radiating elements in the column. As the vertical separation increases, the elevation angle HPBW decreases. However, there are two limitations to the vertical spacing. First, the vertical distance between the radiating elements in a given column of the array should be spaced between about 0.6 λ and 0.8 λ apart. If the radiating elements are spaced further apart, the elevation sidelobes tend to become larger in exactly the same manner as the azimuth sidelobes become larger as the columns of radiating elements are spaced further apart in the horizontal direction. Thus, in general, to increase the vertical spacing between the top and bottom radiating elements in a column, additional radiating elements generally need to be added, which increases the cost and weight of the antenna, or requires acceptance of higher elevation sidelobe levels. Second, base station antenna manufacturers typically only manufacture several 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 their size.

As shown in fig. 2A, in the base station antenna 200, the radiating elements 122 in each array 210 are arranged in 2 x 1 sub-arrays 224 (i.e., each sub-array includes two radiating elements 122 in each row of the array 210), and each sub-array 224 is connected to a respective output of a pair of phase shifter/power divider circuits (one for each polarization). If an antenna with this design includes a phase shifter/power divider circuit with seven outputs, a total of seven radiating elements may be included in each column 220 of the array 210. This may not be enough radiating elements to maintain proper vertical spacing between the radiating elements while also achieving sufficient vertical height for the columns to achieve the desired elevation angle HPBW, and thus the elevation angle HPBW of the base station antenna 200 may be too large.

By connecting two radiating elements per column to each output of the phase shifter/power divider circuit, the number of radiating elements in each column can be increased to, for example, ten radiating elements (for a1 x 5 phase shifter/power divider circuit) or 14 radiating elements (for a1 x 7 phase shifter/power divider circuit). By increasing 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 quite far apart in the vertical direction to achieve the desired elevation HPBW value (typically much less than the azimuth HPBW value).

In particular, fig. 3A-3B schematically illustrate a dual beam base station antenna 300 that includes four columns 320-1 through 320-4 (in two arrays 310-1 and 310-2) of radiating elements 122. Each column 320 comprises ten radiating elements 122, respectively, and the radiating elements 122 are likewise mounted on a V-shaped reflector (already described previously). The base station antenna 300 comprises 1 x 5 phase shifter/power divider circuits, so a2 x 2 sub-array 324 of radiating elements 122 is connected to each output of each phase shifter/power divider circuit. Fig. 3C and 3D are simulated azimuth and elevation patterns of the base station antenna 300. As shown in fig. 3C, the base station antenna 300 also exhibits high azimuth sidelobes, as is expected in view of the similarity of the design of the base station antennas 200 and 300 in the horizontal plane, like the base station antenna 200 of fig. 2A-2B. As shown in fig. 3D, the base station antenna 300 also exhibits high elevation sidelobes. This result is because the radiating elements 122 must be spaced quite far apart in the elevation plane in order to meet the elevation HPBW requirement, and this increased spacing results in high elevation sidelobes.

As described above, the high azimuth sidelobes exhibited by the base station antennas 200 and 300 can be attributed to the large spacing of the adjacent radiating elements 122 in the horizontal direction, which is necessary to achieve sufficient narrowing of the azimuth HPBW. Fig. 4A and 4B illustrate another dual-beam base station antenna 400 that adds a third column 420 of radiating elements 122 to each panel 104 of reflector 102, which significantly reduces the horizontal spacing between adjacent radiating elements 122. As shown in fig. 4C and 4D, which are the azimuth and elevation patterns of the base station antenna 400, the antenna 400 does exhibit reduced azimuth side lobe levels, with peak side lobes approximately 13dB lower than the peak gain of the antenna pattern. Although this performance is improved, it is still only at the acceptable edge. The azimuth sidelobe level of the base station antenna 400 remains high due to poor isolation between adjacent columns 430 of radiating elements 122. This poor isolation occurs because the radiating elements 122 are too close together. The elevation sidelobes also remain too high (peak approximately 10dB below peak gain) for the same reasons discussed above with respect to base station antenna 300. In addition, cross-polarization discrimination at the boresight is also poor (about 10dB below the common polarization level) due to the close spacing of the radiating elements 122. Thus, even when the number of radiating elements 122 per column 420 increases to ten radiating elements 122 and the number of columns 420 per array 410 increases to three, the performance of the base station antenna 400 remains unacceptable for many applications.

Fig. 5A-5B illustrate a conventional, up-to-date, non-lensed dual-beam base station antenna 500 that includes a V-shaped reflector 102 having three columns of radiating elements mounted on each of its panels 104. Base station antenna 500 differs from base station antenna 400 in that the center column 520-2, 520-5 of radiating elements 122 on each panel 104 is vertically opposite the other two columns 520-1, 520-3 of radiating elements 122; 520-4, 520-6 are offset. This offset increases the distance between the radiating elements 122 in adjacent columns 520. The radiating elements 122 are arranged in offset 3 x 2 sub-arrays 524. As shown in fig. 5A, the radiating elements 122 are spaced less than 0.9 λ apart (typically about 0.8 λ), and adjacent columns 520 are separated by 0.5 λ.

By offsetting the center column 520-2, 520-5 relative to the remaining columns 520, the spacing between adjacent radiating elements is increased. As shown in fig. 5C-5D, this serves to significantly reduce the elevation sidelobes and cross-polarization levels so that both are well within acceptable ranges. However, the azimuth sidelobe level is about 13dB below the peak, still at the edge of the acceptable range.

In accordance with an embodiment of the present invention, an improved dual beam base station antenna is provided that includes first and second arrays of radiating elements that may be mounted on respective first and second main panels of a substantially 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. Compared to the prior art base station 500 of fig. 5A-5B, the array is "sparse" in the vertical direction because they include fewer radiating elements per column. Most or all of the radiating elements in each array may be arranged in a three radiating element sub-array that includes radiating elements from each of the three columns in the array. Thus, the radiating elements in each of these sub-arrays may be arranged in a triangular pattern. Each sub-array may be coupled to a respective output of the phase shifter/power divider circuit (for each polarization). In some embodiments, each sub-array may be mounted on a respective feed plate comprising a power divider (for each polarization) that further splits the sub-components of the RF signal output by the respective outputs of the phase shifter/power divider circuit, thereby feeding all radiating elements in the sub-array with a portion of the RF signal output through the outputs of the phase shifter/power divider circuit.

A base station antenna according to an embodiment of the present invention may include substantially fewer radiating elements than the nearest dual-beam base station antenna 500 of fig. 5A-5B. For example, in some embodiments, a dual-beam base station antenna according to embodiments of the present invention may include 30-33% fewer radiating elements than base station antenna 500. By thinning the array in the vertical direction, the vertical spacing between adjacent radiating elements is increased. Generally, as explained in the discussion above, this is expected to increase side lobes in the elevation pattern. The skilled person will appreciate that such increased elevation sidelobe levels are undesirable. However, the base station antenna according to an embodiment of the present invention may achieve elevation sidelobe performance levels comparable to the base station antenna 500 of fig. 5A-5B, since coupling between radiating elements in adjacent columns is reduced, which also may help to increase the elevation sidelobe levels. Moreover, by increasing the vertical distance between adjacent radiating elements, the physical separation between radiating elements in adjacent columns is increased (coupling is reduced). In fact, the increased physical separation between the radiating elements may allow the columns to be spaced closer together in the horizontal direction. The azimuth sidelobe level of the base station antenna according to an embodiment of the present invention may be significantly improved compared to the base station antenna 500 due to reduced coupling and/or tighter horizontal column spacing. Moreover, the reduced horizontal spacing between columns may reduce the width of the antenna, which is also desirable, particularly in multi-band antenna applications.

Fig. 6A-6C illustrate a dual-beam base station antenna 600 according to a first embodiment of the present invention. In particular, fig. 6A is a schematic front view of an antenna 600 (with the radome removed) illustrating the location of the radiating elements and the arrangement of the radiating elements in the sub-array. Fig. 6B is a cross-section of the base station 600 illustrating the positioning of the radiating elements on the V-shaped reflector. Fig. 6C is a block diagram illustrating a feed network of one of the arrays included in the base station antenna 600.

As shown in fig. 6A-6B, the base station antenna 600 is an elongated structure extending along a longitudinal axis L. When the base station antenna 600 is installed for normal use, the longitudinal axis L will typically extend along a vertical axis, but in some cases the base station antenna 600 may be tilted a few degrees from vertical to impart mechanical downtilt to the antenna beam formed by the base station antenna 600. As further shown in fig. 6A, the base station antenna 600 has a length L and a width W, and a depth. The azimuth boresight pointing direction of the base station antenna 600 refers to a horizontal axis a extending from the base station antenna 600 to the center of the sector served by the base station antenna 600 in the azimuth plane₁。

As shown in fig. 6A-6B, dual-beam base station antenna 600 includes six columns 620-1 through 620-6 of radiating elements 122. Columns 620-1 through 620-3 are mounted to extend forward from panel 104-1 of reflector 102 to form a first multi-column array 610-1, and columns 620-4 through 620-6 are mounted to extend forward from panel 104-2 to form a second multi-column array 610-2. The center column 620-2, 620-5 on each panel 104 is offset in the vertical direction relative to the other two columns 620 (in the depicted embodiment, the center columns 620-2, 620-5 are offset upward, but may be offset downward in other embodiments). Each column 620 includes a total of seven radiating elements 122. Thus, each array 610 includes only a total of twenty-one radiating elements 122, as compared to thirty radiating elements 122 included in each array 510 of the base station antenna 500. The radiating elements 122 in each array 610 are arranged in a triangular sub-array 624, the triangular sub-array 624 including one radiating element 122 from each column 620. Each sub-array 624 in array 620 may be coupled to a respective output of a pair of phase shifter/power divider circuits (i.e., one for each polarization), as will be discussed in more detail below with reference to fig. 6C.

As further shown in fig. 6A, the radiating elements 122 in each column 620 may be spaced significantly farther apart (i.e., in the vertical direction) than the radiating elements 122 in the base station antenna 500. In particular, adjacent radiating elements 122 in column 620 may be spaced apart by 1.2 λ to 1.8 λ as compared to a spacing of less than 0.9 λ in base station antenna 500. This increased spacing allows the number of radiating elements 122 included in each array 610 of the base station antenna 600 to be significantly sparse. While in some embodiments adjacent radiating elements 122 in column 620 may be spaced apart by 1.2 λ to 1.8 λ, in other embodiments the spacing may be between 1.3 λ and 1.7 λ, or between 1.4 λ and 1.6 λ. Further, due to the increased spacing in the vertical direction, the outer columns 620 may be moved closer together (e.g., to between 0.5 λ and 0.95 λ, or between 0.6 λ and 0.9 λ, or between 0.7 λ and 0.8 λ) as compared to the spacing of 1 λ in the base station antenna 500.

Referring to fig. 6C, a feed network 650 for one of the arrays 610 of radiating elements is schematically depicted. As shown in FIG. 6C, antenna 600 includes a pair of RF ports 640-1, 640-2 that may be connected to corresponding ports on a remote radio head. The first RF port 640-1 may be used for-45 polarization, while the second RF port 640-2 may be used for +45 polarization. The RF ports 640-1, 640-2 are coupled to respective phase shifter/power divider circuits 630-1, 630-2. In the depicted embodiment, each phase shifter/power divider circuit 630 is configured to split the RF signal input thereto into five subcomponents and then apply an adjustable amount of phase taper on the five subcomponents in order to electrically downtilt the resulting antenna beam by a desired amount. Each output of the phase shifter/power divider circuit 630-1 is coupled to a tilted-45 dipole radiator of the radiating element 122 included in a respective one of the sub-arrays 624, and each output of the phase shifter/power divider circuit 630-2 is coupled to a tilted +45 dipole radiator of the radiating element 122 included in a respective one of the sub-arrays 624. The three radiating elements 122 included in each sub-array 624 may be mounted on a respective sub-array feed plate 626, and a pair of 1 x 3 power dividers 628 (one for each polarization) may be included on the sub-array feed plate 626. Each 1 x 3 power splitter 628 may further split the power of the RF signal received at the sub-array feed plate 626 to feed a portion thereof to each radiating element 122. The 1 x 3 power splitter 628 may split the power equally or unequally. In many cases, the 1 x 3 power splitter 628 may be configured to deliver more power to the radiating elements of the middle columns 620-2, 620-5 than to the radiating elements of the outer column 620. For example, in some embodiments, the 1 x 3 power splitter 628 may split the RF signal input thereto to provide more power to the radiating elements 122 in the center columns 620-2, 620-5 than to the radiating elements 122 in the outer columns 620-1, 620-3, 620-4, 620-6. In one example embodiment, the radiating elements 122 in the middle columns 620-2, 620-5 may receive between 40% -70% of the power input to each of the 1 x 3 power dividers 628, with the remaining power split between the radiating elements 122 in the outer columns 620-1, 620-3, 620-4, 620-6. For example, the radiating elements 122 in the middle columns 620-2, 620-5 may receive 50% of the power of the RF signal input to each of the 1 × 3 power dividers 628, while the radiating elements 122 in the outer columns 620-1, 620-3, 620-4, 620-6 each receive 25% of the power of the RF signal input to each of the 1 × 3 power dividers 628.

Fig. 6D and 6E are graphs of simulated "envelopes" of the azimuth and elevation patterns of the base station antenna of fig. 6A-6C. As shown in fig. 6D, the antenna beam generated by the base station antenna 600 has a slightly larger azimuth HPBW than the antenna beam generated by the base station antenna 500, but the azimuth HPBW is still within an acceptable range. Moreover, the antenna beam generated by the base station antenna 600 has significantly reduced azimuth side lobe levels, which are at least 20dB lower than the peak gain. The sidelobes in elevation of the generated antenna beam may be comparable to those of the antenna beam generated by the base station antenna 500.

Simulations have been performed to analyze various performance parameters of the dual-beam base station antenna 600 of fig. 6A-6C. Table I below summarizes the results of these simulations. As shown, separate simulations have been run for five different sub-bands in the 1695MHz-2690MHz cellular frequency band, with simulations performed at multiple frequencies within each sub-band. To account for the effect of electrical downtilt on antenna performance, simulations were performed at electrical downtilt values of 0 ° and 12 °.

TABLE I

As shown in table I, the average azimuth HPBW of 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 subbands. A 12dB azimuth beamwidth in the range of 73-55 is acceptable and the azimuth pointing angle can be chosen 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 reflectors. Although not listed in table I, the peak azimuth sidelobes are more than 15dB lower than the peak gain across all subbands. The elevation sidelobes exceed-15 dB (see fig. 6E), but are in all cases at least 14dB lower than the peak gain, which is acceptable. Cross-polarization discrimination performance is fully acceptable in all but the first sub-band. Thus, the simulation results shown in table I indicate that the base station antenna 600 provides acceptable performance for sector splitting applications. This performance is at least comparable to state-of-the-art conventional dual-beam base station antenna 500, but base station antenna 600 includes much fewer radiating elements and may have a smaller width.

Fig. 7A is a schematic front view of a dual-beam base station antenna 700 that is a modified version of the base station antenna 600 of fig. 6A-6C. Fig. 7B is a cross-sectional view of the base station 700. As can be seen by comparing fig. 7A-7B with fig. 6A-6B, the base station antennas 600 and 700 are almost identical to each other, the main difference being that the middle columns 720-2, 720-5 of radiating elements 122 in the base station antenna 700 each have only six radiating elements 122, instead of seven. Thus, the arrays 710-1, 710-2 included in the base station antenna 700 each have only twenty radiating elements 122, as compared to twenty-one radiating elements 122 included in each array 610 of the base station antenna 600. As shown in fig. 7A, the top three subarrays 724-1 and the bottom three subarrays 724-1 in each array 710 may be identical to the corresponding subarrays 624 in the base station antenna 600. However, the middle sub-array 724-2 in the base station antenna 700 includes only two horizontally aligned radiating elements 122. The performance of the array 710 is comparable to the array 610 of the base station antenna 600, albeit with one fewer radiating element 122.

Fig. 8 is a schematic front view of a dual-beam base station antenna 800 that is a modified version of the base station antenna 700 of fig. 7A-7C. As can be seen by comparing fig. 8 with fig. 7A, the base station antennas 800 and 700 are almost identical to each other, the main difference being that the bottom three sub-arrays 824-3 in array 810-2 are flipped upside down relative to the corresponding three sub-arrays 724-1 in array 710-2 of base station antenna 700. It will be appreciated that similar changes may be made to arrays 710-1 and 810-1 if desired, or that the top three sub-arrays may be inverted in place of and/or in addition to the bottom three sub-arrays in any of base station antennas 700 and/or 800.

Fig. 9A is a schematic front view of a feed plate 900 that may be used to implement at least some feed plates in any base station antenna according to embodiments of the invention. As shown in fig. 9A, the feed plate 900 has a V-shaped design. Mounting locations for mounting the radiating elements are provided near the apex of the V and at the distal end of the V. The mounting locations may define a triangle. Feed board 900 may include a printed circuit board feed board having a ground plane on its back side and conductive traces on its front side. The 1 x 3 power divider circuit 628 included in the base station antenna according to the embodiment of the present invention may also be formed at the front side of the printed circuit board. In some embodiments, the 1 x 3 power divider circuit 628 may include, for example, three Wilkinson power dividers. The V-shaped feed plate design shown in fig. 9A may be advantageous because it may allow a greater number of feed plates 900 to be manufactured from a given size of printed circuit board, thereby reducing cost. As shown in fig. 9B, in other embodiments, a feed plate 910 having a triangular shape may be provided. Feed board 910 typically requires more printed circuit board material than feed board 900 and therefore is more costly, but may also include additional space for implementing a1 x 3 power divider circuit, as well as better shapes for routing traces on the front side of the printed circuit board.

Figure 10A is a cross-sectional view of a dual-beam base station antenna 1000 according to an embodiment of the present invention. In particular, the antenna 1000 includes (i) a high-band dual-beam layout having a first high-band array 1010-1 and a second high-band array 1010-2, and (ii) a low-band array 1030. The high band arrays 1010-1 and 1010-2 may be on respective sloped portions (e.g., panels) 104-1 and 104-2 of the reflector 102 inside the radome 1011 of the antenna 1000, while the low band array 1030 may be on a flat middle portion 104-M of the reflector 102, the flat middle portion 104-M being between the sloped portions 104-1 and 104-2 in the horizontal direction H. The flat middle portion 104-M is coplanar with the horizontal plane HP, while the inclined portions 104-1 and 104-2 are inclined with respect to the horizontal plane HP. In some embodiments, the radome 1011 may have a width W in the horizontal direction H of no more than 395 millimeters ("mm").

High-band array 1010-1 can include a first plurality of vertical columns 1020 of high-band radiating elements 122, and high-band array 1010-2 can include a second plurality of vertical columns 1020 of high-band radiating elements 122. For example, array 1010-1 may include three high-band vertical columns 1020-1, 1020-2, and 1020-3, and array 1010-2 may include another three high-band vertical columns 1020-4, 1020-5, and 1020-6. Also, 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 band that includes 1695MHz-2690MHz or a portion thereof, while the term "low band" refers to a band that includes 694MHz-960MHz or a portion thereof.

Figure 10B is a cross-sectional view of a dual-beam base station antenna 1000R according to an embodiment of the present invention. Like antenna 1000 (fig. 10A), antenna 1000R includes a low-band array 1030 integrated between high-band arrays 1010-1 and 1010-2. However, unlike antenna 1000, antenna 1000R includes a reflector 102R having a concave flat middle portion 104-RM. Because the low band array 1030 is on the concave flat middle portion 104-RM, the RF performance of the antenna 1000R may exceed that of the antenna 1000 because the low band radiating element 1021 may "see" more of the reflector 102R than it may see "the reflector 102 (fig. 10A). Also, the low-band radiating elements 1021 on the concave flat mid-portion 104-RM may not protrude as far in the forward direction F as the high-band radiating elements 122 (fig. 10A), so the antenna 1000R may be smaller than the antenna 1000.

The concave flat mid-portion 104-RM has a depth D spaced from the horizontal plane HP in the forward direction F. For example, the depth D may be 20-40 mm. Moreover, the angled portions 104-1 and 104-2 have respective ends (e.g., endpoints) 104-1E and 104-2E that are adjacent to each other and are in or nearly in the horizontal plane HP. Thus, recessed flat middle portion 104-RM may be recessed approximately 20-40mm relative to end portions 104-1E and 104-2E. As shown in fig. 10B, the inclined portions 104-1 and 104-2 may be inclined toward each other in a forward direction F toward the front side of the radome 1011.

By integrating the low-band radiating element 1021 with the high-band radiating element 122 on the reflector 102R (or 102), the antenna 1000R (or 1000) can provide an azimuth beam width (e.g., HPBW) of, for example, about 65 ° in the low band in addition to providing a dual-beam azimuth beam width (e.g., HPBW) of about 33 ° in the high band. Moreover, the reflector 102R (or 102) may be tilted and shaped to improve beam-to-beam isolation for the dual beam arrangement. For example, the inclination of the inclined portions 104-1 and 104-2 and the increase in spacing between the inclined portions 104-1 and 104-2 due to the concave flat middle portion 104-RM (or flat middle portion 104-M) may reduce coupling between the high-band arrays 1010-1 and 1010-2.

In some embodiments, high-band arrays 1010-1 and 1010-2 may each have triangular sub-arrays mounted on reflector 102R (or 102). Such a triangular arrangement of the high-band radiating elements 122 may reduce cost by using fewer radiating elements 122 than conventional arrangements, and may reduce coupling between the radiating elements 122 and improve space utilization in the antenna 1000R (or 1000).

Fig. 10C and 10D are schematic front views of the base station antenna 1000R of fig. 10B with the radome 1011 removed. The low band array 1030 is omitted from the view of fig. 10D for simplicity of illustration. As shown in fig. 10C and 10D, the high-band vertical columns 1020 may be vertically staggered in a vertical direction V, where the vertical direction V may be perpendicular to the forward direction F and the horizontal direction H. Staggering successive ones of the high-band vertical columns 1020 may advantageously improve isolation therebetween by increasing the distance between adjacent radiating elements 122.

For example, consecutive ones of the high-band vertical columns 1020-1, 1020-2, and 1020-3 can be vertically staggered with respect to one another, and consecutive ones of the high-band vertical columns 1020-4, 1020-5, and 1020-6 can be vertically staggered with respect to one another. Thus, high-band vertical column 1020-2 may be vertically staggered with respect to high-band vertical columns 1020-1 and 1020-3, while high-band vertical column 1020-5 may be vertically staggered with respect to high-band vertical columns 1020-4 and 1020-6.

Moreover, array 1010-1 (fig. 10B) may have a first triangular arrangement in which each radiating element 122 of high-band vertical column 1020-2 defines a triangular shape with the closest respective radiating element 122 of high-band vertical columns 1020-1 and 1020-3, and array 1010-2 (fig. 10B) may have a second triangular arrangement in which each radiating element 122 of high-band vertical column 1020-5 defines a triangular shape with the closest respective radiating element 122 of high-band vertical columns 1020-4 and 1020-6. The second triangular arrangement may be inverted relative to the first triangular arrangement. Thus, the high-band vertical columns 1020-3 and 1020-4 may be vertically staggered with respect to each other, where the high-band vertical columns 1020-3 and 1020-4 may be the innermost (i.e., closest to the concave flat middle portion 104-RM) high-band vertical column 1020 on their respective sloped portions 104-1 and 104. This may advantageously improve isolation between the innermost radiating elements 122 on opposite sides of the concave flat mid-portion 104-RM. Also, high-band vertical column 1020-2 may be aligned in horizontal direction H with high-band vertical columns 1020-4 and 1020-6, and high-band vertical column 1020-5 may be aligned in horizontal direction H with high-band vertical columns 1020-1 and 1020-3.

Each high-band radiating element 122 may have a respective center point 122C (fig. 10C). Similarly, each low-band radiating element 1021 may have a respective center point 1021C (fig. 10C). Thus, as used herein with respect to the vertical column(s) of radiating elements 122 and/or the vertical column(s) of radiating elements 1021, the term "alignment" may refer to the alignment of center point 122C and/or center point 1021C. Similarly, as used herein with respect to the vertical column(s) of radiating elements 122 and/or the vertical column(s) of radiating elements 1021, the term "staggered" may refer to a staggering of center points 122C and/or center points 1021C. Also, as shown in fig. 10C, the respective center points 1021C of the radiation elements 1021 may not be aligned in the horizontal direction H with respect to the respective center points 122C of any of the radiation elements 122.

Figure 11A is a cross-sectional view of a dual-beam base station antenna 1100 according to an embodiment of the present invention. Similar to the base station antenna 1000R (FIG. 10B), the antenna 1100 may include a reflector 102R having first and second angled portions 104-1 and 104-2 and a recessed flat middle portion 104-RM between the angled portions 104-1 and 104-2 and recessed relative to its respective adjacent ends 104-1E and 104-2E (FIG. 10B). However, as compared to antenna 1000R, antenna 1100 may include high-band radiating element 122L, which high-band radiating element 122L has a lower cost and/or smaller size than radiating element 122 (fig. 10B). Additionally or alternatively, the antenna 1100 may include a low-band radiating element 1021L that is of lower cost and/or small size than the radiating element 1021 (fig. 10B).

In particular, the antenna 1100 may have a first high-band array 1110-1 and a second high-band array 1110-2, the first high-band array 1110-1 including a first plurality of vertical columns 1120 of radiating elements 122L on the angled portion 104-1, and the second high-band array 1110-2 including a second plurality of vertical columns 1120 of radiating elements 122L on the angled portion 104-2. Each radiating element 122L may be a low-cost sheet-metal (sheet-metal) dipole. Moreover, antenna 1100 may have a low band array 1130, which may be a vertical column of radiating elements 1021L on concave flat middle portion 104-RM, and each radiating element 1021L may be a low cost sheet metal dipole. By using sheet metal on e.g. a plastic frame, a low cost and relatively compact dipole can be provided. As the size of radiating element 122L and/or radiating element 1021L decreases, the mutual coupling may also decrease, resulting in improved RF performance of antenna 1100.

Fig. 11B is a schematic front view of the base station antenna 1100 of fig. 11A with the radome 1011 removed. Because antenna 1100 may have reduced mutual coupling between its radiating elements 122L (due to the size of radiating elements 122L), the first triangular arrangement of array 1110-1 (fig. 11A) may not be inverted (but may be duplicated) relative to the second triangular arrangement of array 1110-2 (fig. 11A), as the concave flat middle portion 104-RM between the two triangular arrangements may provide sufficient isolation between the two triangular arrangements.

Figure 12A is a cross-sectional view of a dual-beam base station antenna 1200 according to an embodiment of the present invention. Similar to the base station antenna 1000 (fig. 10A), the antenna 1200 may include a reflector 102 having a first angled portion 104-1 and a second angled portion 104-2 and a flat middle portion 104-M between the angled portions 104-1 and 104-2. However, as opposed to antenna 1000, antenna 1200 may include high-band radiating element 122 on flat middle portion 104-M. For example, the first high band region 1210-1 of the antenna 1200 may include vertical columns 1220-1 and 1220-2 on the slanted portion 104-1, the second high band region 1210-2 of the antenna 1200 may include vertical columns 1220-5 and 1220-6 on the slanted portion 104-2, and the middle third high band region 1210-M of the antenna 1200 may include vertical columns 1220-3 and 1220-4 on the flat middle portion 104-M.

Fig. 12B is a schematic front view of the base station antenna 1200 of fig. 12A with the radome 1011 removed. As shown in FIG. 12B, each of the areas 1210-1, 1210-2, and 1210-M may include vertically staggered vertical columns 1220. In some embodiments, the leftmost vertical column 1220-3 in region 1210-M may be staggered with respect to the rightmost vertical column 1220-2 in region 1210-1, and the rightmost vertical column 1220-4 in region 1210-M may be staggered with respect to the leftmost vertical column 1220-5 in region 1210-2. Also, vertical column 1220-1 may be aligned with vertical column 1220-3 and vertical column 1220-5 in horizontal direction H, and vertical column 1220-2 may be aligned with vertical column 1220-4 and vertical column 1220-6 in horizontal direction H. Thus, each radiating element 122 may define a triangular shape with two adjacent radiating elements 122 in adjacent vertical columns 1220. The replication of these triangular shapes throughout the antenna 1200 may maintain a wide spacing between the radiating elements 122, and thus may reduce mutual coupling therebetween.

To achieve an azimuth beamwidth of approximately 33 ° in the high band, regions 1210-1, 1210-2, and 1210-M may collectively provide two three column high band arrays. For example, the first high-band array may include vertical columns 1220-1, 1220-2, and 1220-3, and the second high-band array may include vertical columns 1220-4, 1220-5, and 1220-6. In each high-band array, one of the vertical columns 1220 (e.g., in region 1210-M) may not be tilted, but may have an adjusted phase.

In some embodiments, the low-band vertical column 1230 may be on the flat middle portion 104-M between the vertical columns 1220-3 and 1220-4. Thus, the high band radiating element 122 and the low band radiating element 1021 may be on the same plane of the reflector 102. By adjusting the phase at the radiating element 122 on the flat middle portion 104-M, dual-beam performance with a beamwidth of about 33 ° in the high frequency band may be improved. Also, to accommodate the combination of the radiating element 122 and the radiating element 1021, the flat middle portion 104-M may be relatively wide in the horizontal direction H, allowing the radiating element 1021 to "see" more of the reflector 102. For example, the width of the flat middle portion 104-M may be approximately equal to the width of each of the angled portions 104-1 and 104-2. Because it has a single reflector 102 for all radiating elements 122 and 1021, antenna 1200 can also be more easily manufactured than an antenna having high and low band radiating elements on separate reflectors.

Figure 13A is a cross-sectional view of a dual-beam base station antenna 1300 in accordance with an embodiment of the present invention. Similar to base station antenna 1200 (fig. 12A), antenna 1300 may include high band radiating element 122 and low band radiating element 1021 on flat middle portion 104-M of reflector 102. For example, the first high frequency band region 1310-1 may include vertical columns 1320-1 and 1320-2 on the first angled portion 104-1 of the reflector 102, the second high frequency band region 1310-2 may include vertical columns 1320-5 and 1320-6 on the second angled portion 104-2 of the reflector 102, and the middle third high frequency band region 1310-M may include vertical columns 1320-3 and 1320-4 on the flat middle portion 104-M. To achieve an azimuth beamwidth of approximately 33 ° in the high band, regions 1310-1, 1310-2, and 1310-M may collectively provide two three column high band arrays.

However, as opposed to antenna 1200, 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 with respect to first vertical column 1330-1. Vertical columns 1330-1 and 1330-2 may both be on 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 interleaved between different vertical columns 1330-1 and 1330-2 to reduce the azimuth beamwidth of the low band array.

Fig. 13B is a schematic front view of the base station antenna 1300 of fig. 13A with the radome 1011 removed. As shown in fig. 13B, each radiating element 1021 of the vertical column 1330-1 can be between a pair of radiating elements 122 of the vertical column 1320-3 in the vertical direction V. Similarly, each radiating element 1021 of the vertical column 1330-2 can be between a pair of radiating elements 122 of the vertical column 1320-4 in the vertical direction V. Also, in some embodiments, the vertical columns 1330-1 and 1330-2 may collectively include no more than five radiating elements 1021. For example, the vertical column 1330-1 may have only three radiating elements 1021, while the vertical column 1330-2 may have only two radiating elements 1021.

Figure 14A is a cross-sectional view of a dual-beam base station antenna 1400 in accordance with an embodiment of the present invention. Antenna 1400 includes a reflector arrangement 102A in which all of high-band radiating elements 122 and all of low-band radiating elements 1021 are distributed among first and second angled portions 104-1 and 104-2 of reflector arrangement 102A, which may be sheet metal. The reflector arrangement 102A does not have a flat middle portion 104-M (fig. 10A) or a recessed flat middle portion 104-RM (fig. 10B), and thus can reduce costs. Thus, in some embodiments, the angled portions 104-1 and 104-2 may be respective reflector surfaces that are angled with respect to each other and are not connected by a flat surface therebetween. The angled portions 104-1 and 104-2 of the reflector arrangement 102A may thus be two separate reflectors, respectively.

The first high-band array 1410-1 of the antenna 1400 may include vertical columns 1420-1, 1420-2, and 1420-3 on the angled portion 104-1, and the second high-band array 1410-2 of the antenna 1400 may include vertical columns 1420-4, 1420-5, and 1420-6 on the angled portion 104-2. The first low frequency band region 1430-1 may also be on the slanted portion 104-1 and the second low frequency band region 1430-2 may also be on the slanted portion 104-2. Also, while fig. 14A illustrates radiating element 1021, in some embodiments, regions 1430-1 and 1430-2 may alternatively use a compact/low cost radiating element 1021L (fig. 11A).

Fig. 14B is a schematic front view of the base station antenna 1400 of fig. 14A with the radome 1011 removed. As shown in FIG. 14B, consecutive ones of the vertical columns 1420-1 through 1420-6 may be vertically staggered. In some embodiments, each low-band radiating element 1021 in region 1430-1 may be between a pair of high-band radiating elements 122 of a vertical column 1420-3 in the vertical direction V. Similarly, each low-band radiating element 1021 in region 1430-2 may be between a pair of high-band radiating elements 122 of a vertical column 1420-4 in the vertical direction V. For example, region 1430-1 may be a single vertical column aligned in the vertical direction V with vertical column 1420-3, while region 1430-2 may be a single vertical column aligned in the vertical direction V with vertical column 1420-4. Regions 1430-1 and 1430-2 may be part of the same interleaved low band array.

Figure 15A is a cross-sectional view of a dual-beam base station antenna 1500 in accordance with an embodiment of the present invention. The antenna 1500 has a reflector 102R that includes a concave flat middle portion 104-RM between the angled portions 104-1 and 104-2. The first high band array 1510-1 and the first low band array 1530-1 can both be on the sloped portion 104-1. The second high band array 1510-2 and the second low band array 1530-2 can both be on the sloped portion 104-2. Also, the middle third high frequency band array 1510-M may be on the concave flat middle portion 104-RM.

The recessed flat middle portion 104-RM may be a flat surface that is recessed relative to the respective adjacent end portions 104-1E and 104-2E of the inclined portions 104-1 and 104-2. Thus, the concave flat middle portion 104-RM may be referred to herein as a "concave 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 the high band radiating elements 122 (i.e., not the low band radiating elements 1021). Also, to reduce coupling due to the high-band array 1510-M, in some embodiments, the width W of the antenna 1500 may be wider than the width of the antennas 1000 (fig. 10A), 1000R (fig. 10B), 1100 (fig. 11A), 1200 (fig. 12A), 1300 (fig. 13A), and 1400 (fig. 14A). For example, the width of the antenna 1500 may be up to 498 mm.

Fig. 15B and 15C are schematic front views of the base station antenna 1500 of fig. 15A with the radome 1011 removed. As shown in fig. 15A-15C, array 1510-1 may include vertical columns 1520-1, 1520-2, and 1520-3 on the angled portion 104-1, array 1510-2 may include vertical columns 1520-5, 1520-6, and 1520-7 on the angled portion 104-2, and array 1510-M may include a single vertical column 1520-4 on the concave flat middle portion 104-RM. In some embodiments, the array 1530-1 can be a single vertical column of low band radiating elements 1021 aligned with the high band radiating elements 122 of the vertical column 1520-2 in the vertical direction V, and the array 1530-2 can be a single vertical column of low band radiating elements 1021 aligned with the high band radiating elements 122 of the vertical column 1520-6 in the vertical direction V. By having only the high-band radiating elements 122 on the concave flat middle portion 104-RM, the antenna 1500 can provide increased low-band separation for the arrays 1530-1 and 1530-2.

Consecutive ones of the vertical columns 1520-1, 1520-2, and 1520-3 can be vertically staggered. Thus, the vertical column 1520-2 can be vertically staggered relative to both the vertical columns 1520-1 and 1520-3. Similarly, consecutive ones of the vertical columns 1520-5, 1520-6, and 1520-7 can be vertically staggered.

Fig. 15C also illustrates a high-band triangular arrangement in which the triangular shapes, i.e., the triads (trios) of high-band radiating elements 122, are alternately inverted along the vertical direction V. Thus, the triangular shapes continuous in the vertical direction V are inverted with respect to each other. To achieve these shapes, each vertical column 1520 may have three different center-to-center vertical distances d1, d2, and d3 between successive ones of its radiating elements 122. For example, considering four consecutive radiating elements 122 in a vertical column 1520-2, the first and second radiating elements 122, 122 may have a first distance d1, the second and third radiating elements 122, 122 may have a second distance d2, and the third and fourth radiating elements 122, 122 may have a third distance d 3. The second distance d2 may be twice the first distance d1, and the third distance d3 may be three times the first distance d 1. Due to the different vertical distances d1, d2, and d3 and the vertical staggering between consecutive vertical columns 1520, mutual coupling between the radiating elements 122 may be reduced.

Figure 15D is a schematic front view of a dual-beam base station antenna 1500S (with its radome removed) according to an embodiment of the invention. Similar to antenna 1500 (fig. 15A), antenna 1500S includes high-band vertical columns 1520-1 to 1520-7, where vertical column 1520-4 is on recessed flat middle portion 104-RM. However, unlike the antenna 1500, the low-band vertical columns 1530 of the antenna 1500S are vertically staggered with respect to each other. Specifically, the slanted portion 104-1 has vertical columns 1530-1 and 1530-2 that are vertically staggered with respect to each other, and the slanted portion 104-2 has vertical columns 1530-3 and 1530-4 that are vertically staggered with respect to each other. For example, the vertical columns 1530-1 and 1530-2 can be aligned with the vertical columns 1520-2 and 1520-3, respectively, in the vertical direction V, and the vertical columns 1530-3 and 1530-4 can be aligned with the vertical columns 1520-5 and 1520-6, respectively, in the vertical direction V. In some embodiments, the vertical columns 1530-1 and 1530-2 can be part of the same first interleaved low band array and the vertical columns 1530-3 and 1530-4 can be part of the same second interleaved low band array.

As shown in fig. 10A-15D, the low-band radiating element 1021 may be integrated with the dual beam layout of the high-band radiating element 122. For example, the radiating elements 1021 may share one or more reflector surfaces with the radiating elements 122, or the radiating elements 1021 may be on their own surface that faces in a different direction than the direction of the reflector surfaces of the radiating elements 122. In some embodiments, due to the triangular arrangement of the radiating elements 122, each high-band vertical column may have no more than seven radiating elements 122. Also, each low-band vertical column may have no more than five radiating elements 1021. By integrating the radiating element 1021 with the radiating element 122, the antenna 1000 (fig. 10A), 1000R (fig. 10B), 1100 (fig. 11A), 1200 (fig. 12A), 1300 (fig. 13A), 1400 (fig. 14A), 1500 (fig. 15A), and 1500S (fig. 15D) can provide a beam width of, for example, about 65 ° in the low frequency band in addition to providing a dual beam width of about 33 ° in the high frequency band.

It will be appreciated that this specification describes only a few example embodiments of the invention, and that the techniques described herein have applicability beyond the example embodiments described above.

The above description generally describes the transmit path through the base station antennas described herein. It will be appreciated that the base station antenna includes a bi-directional RF signal path, and that the base station antenna will also be used to receive RF signals. In the receive path, the RF signals will typically be combined, while in the transmit path, the RF signals are split. Thus, it will be clear to those skilled in the art 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 reference numerals refer to like elements throughout.

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

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

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" and/or "comprising," when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.

The aspects and elements of all embodiments disclosed above can be combined in any manner and/or in combination with aspects or elements of other embodiments to provide multiple additional embodiments.

Claims (43)

1. A dual beam base station antenna comprising:

an angled reflector having a first planar panel and a second planar panel angled relative to the first planar panel;

a first array comprising a first plurality of radiating elements mounted to extend forward from the first planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns;

a second array comprising a second plurality of radiating elements mounted to extend forward from the second planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns;

a first phase shifter having an input and a plurality of first phase shifter outputs;

a second phase shifter having an input and a plurality of second phase shifter outputs;

wherein more than half of the first phase shifter outputs are connected to a respective one of a plurality of first sub-arrays, wherein each first sub-array comprises a total of one radiating element from each of three columns in the first array,

wherein more than half of the second phase shifter outputs are connected to a respective one of a plurality of second sub-arrays, wherein each second sub-array comprises a total of one radiating element from each of three columns in the second array.

2. The base station antenna defined in claim 1 wherein the three radiating elements included in each first sub-array are arranged to define a triangle and wherein the three radiating elements included in each second sub-array are arranged to define a triangle.

3. The base station antenna defined in claim 2 wherein the three radiating elements included in each first sub-array are mounted on a common feed board printed circuit board that includes a pair of 1 x 3 power dividers and wherein the three radiating elements included in each second sub-array are mounted on a common feed board printed circuit board that includes a pair of 1 x 3 power dividers.

4. The base station antenna defined in claim 2 wherein the three radiating elements included in each first sub-array include radiating elements in an outer column that are horizontally aligned with one another and radiating elements in an intermediate column that are vertically offset with respect to the radiating elements in the outer column.

5. The base station antenna of claim 1, wherein the outer columns in the first array and the outer columns in the second array are separated in the horizontal direction by between 0.5 λ and 0.95 λ, where λ is a wavelength corresponding to a center frequency of the operating band of the first array and the second array.

6. The base station antenna of claim 5, wherein the radiating elements in a middle column of the first array are vertically offset from nearest radiating elements in outer columns of the first array by between 0.6 λ and 0.9 λ, and the radiating elements in a middle column of the second array are vertically offset from nearest radiating elements in outer columns of the second array by between 0.6 λ and 0.9 λ, where λ is a wavelength corresponding to a center frequency of an operating band of the first array and the second array.

7. The base station antenna of claim 1, wherein the radiating elements in a middle column of the first array are vertically offset from nearest radiating elements in outer columns of the first array by between 0.6 λ and 0.9 λ, and the radiating elements in a middle column of the second array are vertically offset from nearest radiating elements in outer columns of the second array by between 0.6 λ and 0.9 λ, where λ is a wavelength corresponding to a center frequency of an operating band of the first array and the second array.

8. The base station antenna of claim 7, wherein each radiating element is configured to operate in at least a portion of a 1.695MHz to 2.690MHz frequency band.

9. The base station antenna of claim 3, wherein the 1 x 3 power dividers are unequal power dividers and provide a greater amount of power to the radiating elements in the middle column than to the radiating elements in the outer columns.

10. The base station antenna of claim 1, wherein one of the first phase shifter outputs is connected to a third sub-array comprising a total of one radiating element from each outer column in the first array, and wherein one of the second phase shifter outputs is connected to a fourth sub-array comprising a total of one radiating element from each outer column in the second array.

11. The base station antenna of claim 10, wherein the first array comprises an equal number of first sub-arrays above and below the third sub-array, and wherein the second array comprises an equal number of second sub-arrays above and below the fourth sub-array.

12. The base station antenna of claim 1, wherein the first and second arrays each comprise a total of twenty or twenty-one radiating elements.

13. The base station antenna defined in claim 1 wherein each first sub-array comprises a V-shaped feed plate or a triangular-shaped feed plate.

14. The base station antenna of claim 1, wherein the outer columns of the first array and the outer columns of the second array are separated in the horizontal direction by between 0.6 λ and 0.85 λ, where λ is a wavelength corresponding to a center frequency of the operating band of the first array and the second array, wherein the radiating elements in the middle column of the first array are offset in the vertical direction by between 0.7 λ and 0.8 λ relative to the nearest radiating elements in the outer columns of the first array, and the radiating elements in the middle column of the second array are offset in the vertical direction by between 0.7 λ and 0.8 λ relative to the nearest radiating elements in the outer columns of the second array, where λ is a wavelength corresponding to a center frequency of the operating band of the first array and the second array, and wherein each radiating element is configured to operate in at least a portion of 1.695MHz to 2.690 MHz.

15. A dual beam base station antenna comprising:

an angled reflector having a first planar panel and a second planar panel angled relative to the first planar panel;

a first array comprising a first plurality of radiating elements mounted to extend forward from the first planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns; and

a second array comprising a second plurality of radiating elements mounted to extend forward from the second planar panel, wherein the radiating elements extend in three vertically extending columns, and the radiating elements in a middle column of the three vertically extending columns are vertically offset from the radiating elements in the other two columns of the three vertically extending columns;

wherein the first and third columns in the first array and the first and third columns in the second array are separated by between 0.5 λ and 0.95 λ, where λ is a wavelength corresponding to a center frequency of the operating band of the first and second arrays,

wherein the radiating elements in the second column of the first array are offset between 0.6 λ and 0.9 λ in the vertical direction relative to the nearest radiating elements in the first and third columns of the first array, and the radiating elements in the second column of the second array are offset between 0.6 λ and 0.9 λ in the vertical direction relative to the nearest radiating elements in the first and third columns of the second array.

16. The base station antenna of claim 15, wherein all of the first phase shifter outputs are connected to respective ones of a plurality of first sub-arrays, wherein each first sub-array includes a total of one radiating element from each of three columns in the first array, and

wherein all of the second phase shifter outputs are connected to a respective one of a plurality of second sub-arrays, wherein each second sub-array comprises a total of one radiating element from each of three columns in the second array.

17. The base station antenna of claim 15, wherein all but one of the first phase shifter outputs are connected to a respective one of a plurality of first sub-arrays, wherein each first sub-array includes a total of one radiating element from each of three columns in the first array, and

wherein all but one of the second phase shifter outputs are connected to a respective one of a plurality of second sub-arrays, wherein each second sub-array comprises a total of one radiating element from each of three columns in the second array.

18. The base station antenna defined in claim 15 wherein the three radiating elements included in each first sub-array are arranged to define a triangle and wherein the three radiating elements included in each second sub-array are arranged to define a triangle.

19. The base station antenna defined in claim 15 wherein the three radiating elements included in each first sub-array are mounted on a common feed board printed circuit board that includes a pair of 1 x 3 power dividers and wherein the three radiating elements included in each second sub-array are mounted on a common feed board printed circuit board that includes a pair of 1 x 3 power dividers.

20. The base station antenna of claim 19, wherein the 1 x 3 power dividers are unequal power dividers and provide a greater amount of power to the radiating elements in the middle column than to the radiating elements in the outer columns.

21. The base station antenna of claim 17, wherein one of the first phase shifter outputs is connected to a third sub-array comprising a total of one radiating element from each outer column in the first array, and wherein one of the second phase shifter outputs is connected to a fourth sub-array comprising a total of one radiating element from each outer column in the second array.

22. The base station antenna of claim 21, wherein the first array comprises an equal number of first sub-arrays above and below the third sub-array, and wherein the second array comprises an equal number of second sub-arrays above and below the fourth sub-array.

23. The base station antenna of claim 15, wherein the first and second arrays each comprise a total of twenty or twenty-one radiating elements.

24. A base station antenna, comprising:

a reflector including first and second inclined portions and a recessed flat middle portion between the first and second inclined portions and recessed with respect to respective adjacent ends of the first and second inclined portions;

a vertical column of low band radiating elements on a concave flat middle portion of the reflector;

a first plurality of vertical columns of high-band radiating elements on a first angled portion of the reflector; and

a second plurality of vertical columns of high-band radiating elements are on the second angled portion of the reflector.

25. The base station antenna of claim 24, wherein the concave flat middle portion of the reflector is concave 20-40 millimeters relative to the respective adjacent ends of the first and second inclined portions of the reflector.

26. The base station antenna of claim 24, further comprising a radome, wherein the first and second angled portions of the reflector are angled toward each other in a forward direction toward a front side of the radome.

27. The base station antenna according to claim 24,

wherein the first plurality of vertical columns of high-band radiating elements comprises consecutive first, second, and third vertical columns of high-band radiating elements, an

Wherein the second plurality of vertical columns of high-band radiating elements includes consecutive fourth, fifth, and sixth vertical columns of high-band radiating elements.

28. The base station antenna according to claim 27,

wherein the second vertical column of high-band radiating elements is vertically staggered with respect to the first vertical column and the third vertical column of high-band radiating elements, an

Wherein the fifth vertical column of high-band radiating elements is vertically staggered with respect to the fourth vertical column and the sixth vertical column of high-band radiating elements.

29. The base station antenna according to claim 28,

wherein the second vertical column of high-band radiating elements is horizontally aligned with the fourth vertical column and the sixth vertical column of high-band radiating elements, an

Wherein the fifth vertical column of high-band radiating elements is horizontally aligned with the first and third vertical columns of high-band radiating elements.

30. The base station antenna of claim 29, wherein the respective center points of the low-band radiating elements are not horizontally aligned with the respective center points of any high-band radiating elements.

31. The base station antenna of claim 24, wherein an innermost column of the first plurality of vertical columns of high-band radiating elements is vertically staggered with respect to an innermost column of the second plurality of vertical columns of high-band radiating elements.

32. A base station antenna, comprising:

a reflector including first and second inclined portions and a flat middle portion between the first and second inclined portions;

a vertical column of low band radiating elements on a flat middle portion of the reflector;

a first vertically staggered plurality of vertical columns of high-band radiating elements on a first angled portion of the reflector; and

a second plurality of vertically staggered vertical columns of high-band radiating elements, on a second angled portion of the reflector,

wherein an innermost column of the first vertically staggered plurality of vertical columns is vertically staggered relative to an innermost column of the second vertically staggered plurality of vertical columns.

33. The base station antenna of claim 32, further comprising a third vertically staggered plurality of vertical columns of high band radiating elements on the flat middle portion of the reflector.

34. The base station antenna according to claim 33,

wherein the first vertically interleaved plurality of vertical columns includes consecutive first and second vertical columns of high-band radiating elements,

wherein the third vertically staggered plurality of vertical columns includes consecutive third and fourth vertical columns of high-band radiating elements,

wherein the second vertically staggered plurality of vertical columns includes consecutive fifth and sixth vertical columns of high-band radiating elements,

wherein the first vertical column of high-band radiating elements is horizontally aligned with the third vertical column and the fifth vertical column of high-band radiating elements, an

Wherein the second vertical column of high-band radiating elements is horizontally aligned with the fourth vertical column and the sixth vertical column of high-band radiating elements.

35. The base station antenna of claim 32, wherein the flat middle portion of the reflector is recessed relative to respective ends of the first and second angled portions of the reflector adjacent the flat middle portion.

36. The base station antenna according to claim 32,

wherein the vertical column of low band radiating elements comprises a first vertical column of low band radiating elements, an

Wherein the base station antenna further comprises a second vertical column of low band radiating elements that is vertically staggered on the flat middle portion of the reflector and relative to the first vertical column of low band radiating elements.

37. A base station antenna, comprising:

a first reflector surface and a second reflector surface inclined with respect to each other;

a first vertical column of low-band radiating elements on the first reflector surface;

a second vertical column of low-band radiating elements on the second reflector surface;

a first vertically interleaved plurality of vertical columns of high-band radiating elements on the first reflector surface; and

a second vertically staggered plurality of vertical columns of high-band radiating elements on the second reflector surface.

38. The base station antenna of claim 37, further comprising a concave flat intermediate reflector surface between the first and second reflector surfaces and concave relative to respective adjacent ends of the first and second reflector surfaces.

39. The base station antenna according to claim 38,

wherein the first vertically staggered plurality of vertical columns includes consecutive first, second, and third vertical columns of high-band radiating elements,

wherein the second vertically staggered plurality of vertical columns includes consecutive fourth, fifth, and sixth vertical columns of high-band radiating elements, an

Wherein the base station antenna further comprises a seventh vertical column of high band radiating elements on the concave flat intermediate reflector surface.

40. The base station antenna according to claim 39,

wherein the first vertical column of low-band radiating elements is vertically aligned with the second vertical column of high-band radiating elements, an

Wherein the second vertical column of low-band radiating elements is vertically aligned with the fifth vertical column of high-band radiating elements.

41. The base station antenna of claim 39, further comprising a third vertical column and a fourth vertical column of low band radiating elements on the first reflector surface and the second reflector surface, respectively,

wherein the third vertical column of low-band radiating elements is vertically staggered with respect to the first vertical column of low-band radiating elements, an

Wherein the fourth vertical column of low-band radiating elements is vertically staggered with respect to the second vertical column of low-band radiating elements.

42. The base station antenna according to claim 41,

wherein the first vertical column of low band radiating elements is vertically aligned with the second vertical column of high band radiating elements,

wherein the third vertical column of low-band radiating elements is vertically aligned with the third vertical column of high-band radiating elements,

wherein the second vertical column of low-band radiating elements is vertically aligned with the fourth vertical column of high-band radiating elements, an

Wherein the fourth vertical column of low-band radiating elements is vertically aligned with the fifth vertical column of high-band radiating elements.

43. The base station antenna according to claim 39,

wherein the second vertical column of high-band radiating elements includes a succession of first through fourth high-band radiating elements,

wherein the first high-band radiating element and the second high-band radiating element are vertically spaced apart from each other by a first distance,

wherein the second high-band radiating element and the third high-band radiating element are vertically spaced apart from each other by a second distance that is twice the first distance, an

Wherein the third high-band radiating element and the fourth high-band radiating element are vertically spaced apart from each other by a third distance that is three times the first distance.

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