WO2023022813A2

WO2023022813A2 - Base station antennas having at least one rotatable reflector panel that are suitable for sharing by multiple cellular network operators

Info

Publication number: WO2023022813A2
Application number: PCT/US2022/036775
Authority: WO
Inventors: Bjorn Lindmark
Original assignee: Commscope Technologies Llc
Priority date: 2021-08-15
Filing date: 2022-07-12
Publication date: 2023-02-23
Also published as: WO2023022813A3

Abstract

Base station antennas include a first reflector panel having a first array of radiating elements mounted thereon and a second reflector panel having a second array of radiating elements mounted thereon. A housing that includes a radome surrounds the first and second reflector panels. The first and second reflector panels are mounted in a vertically-stacked arrangement, and the second reflector panel is rotatable in an azimuth plane with respect to the first reflector panel so that the first array is configured to generate first antenna beams that provide coverage to a first sector and the second array is configured to generate second antenna beams that provide coverage to a second sector. The second sector may partially overlap the first sector but does not completely overlap the first sector.

Description

BASE STATION ANTENNAS HAVING AT LEAST ONE ROTATABLE REFLECTOR PANEL THAT ARE SUITABLE FOR SHARING BY MULTIPLE CELLULAR NETWORK OPERATORS CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Application Serial No.63/233,300, filed August 15, 2021, the entire content of which is incorporated herein by reference in its entirety. FIELD [0002] The present invention relates to cellular communications systems and, more particularly, to base station antennas that include at least one rotatable reflector panel BACKGROUND [0003] Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as "cells" which are served by respective base stations. The base station may include baseband equipment, radios and one or more base station antennas that are configured to provide two-way radio frequency ("RF") communications with fixed and mobile subscribers ("users") that are positioned throughout the cell. In many cases, each base station is divided into "sectors." In one common configuration, a hexagonally shaped cell is divided into three 120º sectors in the azimuth plane. Each sector is served by one or more base station antennas that have an azimuth Half Power Beamwidth (HPBW) of approximately 65°. The base station antennas may be mounted on a tower or other raised structure, with the radiation patterns (also referred to herein as "antenna beams") that are generated by the base station antennas directed outwardly. Typically, a base station antenna includes one or more phase-controlled arrays of radiating elements, with the radiating elements arranged in one or more vertically-extending columns when the antenna is mounted for use. References herein to the azimuth plane refer to a horizontal plane (i.e., a plane that is parallel to the plane defined by the horizon) that bisects the base station antenna. Reference will also be made herein to the elevation plane, which is a plane extending along a boresight pointing direction of one of the arrays of radiating elements that is perpendicular to the azimuth plane. SUMMARY [0004] Pursuant to embodiments of the present invention, base station antennas are provided that comprise a first reflector panel having a first array of radiating elements mounted thereon, the radiating elements of the first array arranged in at least one vertically-extending column, a second reflector panel having a second array of radiating elements mounted thereon, and a housing that includes a radome, the housing surrounding both the first reflector panel and the second reflector panel. The first reflector panel and the second reflector panel are mounted in a vertically-stacked arrangement. The second reflector panel is rotatable in an azimuth plane with respect to the first reflector panel so that the first array is configured to generate first antenna beams that provide coverage to a first sector and the second array is configured to generate second antenna beams that provide coverage to a second sector, where the second sector partially overlaps the first sector but does not completely overlap the first sector. [0005] In some embodiments, the first antenna beams have fixed azimuth beamwidths that provide coverage to the first sector and the second antenna beams have fixed azimuth beamwidths that provide coverage to the second sector. [0006] In some embodiments, the first reflector panel is rotatable about a first axis. In some embodiments, the second reflector panel is rotatable about the first axis. In other embodiments, the second reflector panel is rotatable about a second axis that is not collinear with the first axis. [0007] In some embodiments, the second reflector panel is configured to rotate at least 30⁰ in the azimuth plane with respect to the first reflector panel. [0008] In some embodiments, the first sector extends for approximately 120⁰ in the azimuth plane and the second sector extends for approximately 120⁰ in the azimuth plane. [0009] In some embodiments, the base station antenna further comprises at least one electric motor that is configured to rotate the first reflector panel and/or the second reflector panel. [0010] In some embodiments, the first sector is associated with a first cellular network operator and the second sector is associated with a second cellular network operator that is different than the first cellular network operator. [0011] In some embodiments, the first reflector panel is fixed with respect to the housing and the second reflector panel is rotatable with respect to the housing. [0012] In some embodiments, the second reflector panel is fixed with respect to the housing and the first reflector panel is rotatable with respect to the housing. [0013] In some embodiments, both the first reflector panel and the second reflector panel are rotatable with respect to the housing. [0014] In some embodiments, the base station antenna further comprises a first rod that is fixedly attached to the first reflector panel and a second rod that is fixedly attached to the second reflector panel, where the first rod extends within an open interior of the second rod. [0015] In some embodiments, the base station antenna further comprises a first electric motor that is configured to rotate the first reflector panel and a second electric motor that is configured to rotate the second reflector panel. [0016] In some embodiments, the base station antenna further comprises a electric motor and a gear system that selectively couples an output shaft of the electric motor to a first rod that is connected to the first reflector panel and a second rod that is connected to the second reflector panel. [0017] In some embodiments, a front portion of the radome has a substantially semi- cylindrical shape. [0018] In some embodiments, wherein the radiating elements of the first array are coupled to a first RF port, the first RF port is coupled to a first radio, and the radiating elements of the second array are coupled to a second RF port, and the second RF port is coupled to a second radio. [0019] In some embodiments, the base station antenna further comprises a support structure and a first rod that is rotatably coupled to the support structure. [0020] In some embodiments, the second array is a multi-column beamforming array that is configured to generate electronically scanned antenna beams that together provide coverage to the second sector. [0021] Pursuant to further embodiments of the present invention, methods of operating a base station antenna are provided. The base station antenna has a longitudinal axis that extends generally perpendicular to an azimuth plane, and includes a first reflector panel having a first array of radiating elements mounted thereon and a second reflector panel having a second array of radiating elements mounted thereon, where the second reflector panel is rotatable with respect to the first reflector panel. Pursuant to these methods, the second reflector panel is rotated with respect to the first reflector panel so that a first boresight pointing direction of the first reflector panel points in a different direction in the azimuth plane than does a second boresight pointing direction of the second reflector panel. First RF signals are fed from a first radio operated by a first cellular network operator to the first array. Second RF signals are fed from a second radio operated by a second cellular network operator that is different than the first cellular network operator to the second array. [0022] In some embodiments, the first reflector panel and the second reflector panel are mounted in a vertically-stacked arrangement. [0023] In some embodiments, the base station antenna further includes a housing that has a radome, the housing surrounding both the first reflector panel and the second reflector panel. [0024] In some embodiments, the first array generates first antenna beams in response to the first RF signals that provide coverage to a first sector that extends for approximately 120⁰ in the azimuth plane, and the second array generates second antenna beams in response to the second RF signals that provide coverage to a second sector that extends for approximately 120⁰ in the azimuth plane, where the second sector only partially overlaps the first sector in the azimuth plane. [0025] In some embodiments, the first RF signals generates first antenna beams that have fixed azimuth beamwidths so as to cover a first sector of a cell of a cellular network operated by the first cellular network operator, and the second RF signals generates second antenna beams that have fixed azimuth beamwidths so as to cover a second sector of a cell of a cellular network operated by the second cellular network operator. In some embodiments, the first sector partially overlaps the second sector. In some embodiments, the first sector extends for approximately 120⁰ in the azimuth plane and the second sector extends for approximately 120⁰ in the azimuth plane. [0026] In some embodiments, rotating the second reflector panel with respect to the first reflector panel comprises using an electric motor to rotate the second reflector panel with respect to the first reflector panel. [0027] In some embodiments, the first reflector panel is fixed with respect to a housing of the base station antenna and the second reflector panel is rotatable with respect to the housing. [0028] In some embodiments, the base station antenna includes a radome having a front portion that has a substantially semi-cylindrical shape. BRIEF DESCRIPTION OF THE DRAWINGS [0029] FIG.1A is a schematic diagram illustrating the cell layout of a first cellular network operated by a first cellular network operator. [0030] FIG.1B is a schematic diagram illustrating the cell layout of a first cellular network operated by a first cellular network operator that also shows the locations of several base stations operated by a second cellular network operator. [0031] FIG.2 is a side view of a base station antenna according to embodiments of the present invention. [0032] FIG.3 is a schematic front view of the base station antenna of FIG.2 with the radome and various other components of the antenna omitted to simplify the figure. [0033] FIGS.4A and 4B are schematic top views of the base station antenna of FIG.2 that illustrate the second reflector panel rotated to two different positions in the azimuth plane. [0034] FIG.5A and 5B are azimuth plots of the antenna beams generated by the base station antenna of FIG.2 with the reflector panels positioned as shown in FIGS.4A and 4B, respectively. [0035] FIG.6 is a schematic front view of the base station antenna according to further embodiments of the present invention with the radome and various other components of the antenna omitted to simplify the figure. [0036] FIGS.7A and 7B are schematic back views of the base station antenna of FIGS. 2-3 that illustrate example mechanical structures for rotating the reflector panels. [0037] FIGS.8A and 8B are schematic horizontal cross-sectional views of base station antennas according to further embodiments of the present invention that include differently- shaped radomes. [0038] FIG.9 is a flow chart diagram illustrating a method of operating a base station antenna according to certain embodiments of the present invention. DETAILED DESCRIPTION [0039] While in many cases a single cellular network operator may own/operate a base station, there are often advantages in multiple cellular network operators sharing a base station. For example, the zoning and permitting costs associated with establishing a base station may be high, and hence splitting those costs across multiple cellular network operators can be advantageous. Because of these advantages, base station antennas are routinely shared by multiple cellular network operators, with some of the arrays of radiating elements included in the antenna being used by a first cellular network operator and other of the arrays being used by a second cellular network operator. Unfortunately, however, the two cellular network operators may have different cell layouts in a geographical area. This can preclude the sharing of resources such as base stations/base station antennas across multiple cellular network operators, as will be discussed with reference to FIGS.1A and 1B. [0040] FIG.1A is a schematic diagram illustrating the cell layout of a first cellular network 1 operated by a first cellular network operator. As shown in FIG.1A, the first cellular network 1 includes a plurality of base stations 10 that provide service to generally hexagonally- shaped regions 20. In the most commonly deployed arrangement, each base station 10 includes three antennas 12, with each antenna 12 configured to cover a different one of three 120º "sectors" 32 in the azimuth plane. This allows each base station 10 to serve a cell 30 that encompasses approximately three of the hexagonally-shaped regions 20 as shown by the circles in FIG.1A that represent the cells 30. The regions 20 typically have the hexagonal shape illustrated in FIG.1A as this arrangement generally facilitates providing full coverage to a large region while reducing the amount of overlap between adjacent cells 30. As is shown in FIG.1A, the boresight pointing direction (shown by the dotted arrows 14 in FIG.1A) in the azimuth plane for the arrays included in each base station antenna 12 of a first base station 10 may be about halfway between two adjacent base stations 10. This may facilitate maximizing coverage while reducing interference [0041] If the first cellular network operator and a second cellular network operator have all of their base stations located in common locations, then both cellular network operators can readily share one or more of the base station antennas 12. However, it is far more common for the two cellular network operators to have base stations 10 that are in different locations. This is illustrated in FIG.1B, where the several base stations 10' operated by the second cellular network operator have been added to the drawing of FIG.1A (note that the hexagonally-shaped regions 20 and the cells 30 for the second cellular network are not shown in FIG.1B). As can be seen in FIG.1B, if the base station antennas 12 are mounted to have boresight pointing directions in the azimuth plane that point in the desired direction for the first cellular network operator, then the base station antennas 12' at the base stations 10' of the second cellular network will not point in the appropriate boresight pointing directions in the azimuth plane. Thus, sharing of base station antennas between the two cellular network operators is difficult or impossible when the base stations 10, 10' of the two cellular network operators are arranged in the manner shown in FIG.1B. [0042] Pursuant to embodiments of the present invention, base station antennas are provided that include at least two reflector panels, where at least one of the reflector panels can be rotated about a vertical axis so that the reflector panel rotates in the azimuth plane. The ability to rotate one or more of the reflector panels so that the two reflector panels have different azimuth boresight pointing directions (where the boresight pointing direction of a reflector panel refers to an axis that extends at a 90⁰ angle through the center of the reflector panel) may facilitate allowing multiple cellular network operators to share the base station antenna, even when the cellular networks operated by the two cellular network operators have significantly different cell structures. [0043] For example, a first cellular network operator may require a three sector base station antenna having three base station antennas that generate antenna beams having boresight pointing directions in the azimuth plane of 0⁰, 120⁰ and 240⁰, respectively. A second cellular network operator that wants to implement a base station in the same location may, however, require that the base station antennas that generate antenna beams having boresight pointing directions in the azimuth plane of 60⁰, 180⁰ and 300⁰. The boresight pointing direction in the azimuth plane of an antenna beam refers to the location where the antenna beam has peak directivity in the azimuth plane. [0044] Due to the different requirements regarding the boresight pointing directions for the antenna beams, these two cellular network operators cannot readily share one of the base station antennas 12 shown in FIG.1B, since conventional base station antennas that are designed to provide coverage to a 120⁰ sector do not have reflector panels with different boresight pointing directions. Moreover, while beamforming base station antennas are known in the art that generate antenna beams that can be electronically scanned to point in different directions in the azimuth plane, beamforming base station antennas typically generate antenna beams having smaller azimuth HPBWs that are not suitable for covering a 120⁰ sector. Moreover, with antenna beams having wide beamwidths in the azimuth plane, such as antenna beams designed to cover 90⁰ or 120⁰ sectors, such electronic scanning does not tend to work very well and is not a practical solution to the above-discussed problem. [0045] By providing base station antennas having at least one rotatable reflector panel, a single base station antenna may be used by the first cellular operator to serve a first sector, where a center of the first sector is at a first angle in the azimuth plane with respect to the base station antenna, while simultaneously being used by the second cellular operator to serve a second sector, where a center of the second sector is at a second angle in the azimuth plane with respect to the base station antenna that differs from the first angle. The difference between the first and second angles typically will be less than 60⁰, although embodiments of the present invention ar not limited thereto. [0046] The base station antennas according to some embodiments of the present invention include a first reflector panel having a first array of radiating elements mounted thereon, the radiating elements of the first array arranged in at least one vertically-extending column, and a second reflector panel having a second array of radiating elements mounted thereon. A housing that includes a radome surrounds both the first reflector panel and the second reflector panel. The first reflector panel and the second reflector panel are mounted in a vertically-stacked arrangement, and the second reflector panel is rotatable in an azimuth plane with respect to the first reflector panel so that the first array is configured to generate first antenna beams that provide coverage to a first sector and the second array is configured to generate second antenna beams that provide coverage to a second sector. In some cases, the second sector may partially overlap the first sector but does not completely overlap the first sector. The first antenna beams may have fixed azimuth beamwidths that provide coverage to the first sector and the second antenna beams may have fixed azimuth beamwidths that provide coverage to the second sector. Multiple arrays of radiating elements may be mounted on each reflector panel. Pursuant to further embodiments of the present invention, methods of operating a base station antenna are provided. The base station antenna has a longitudinal axis that extends generally perpendicular to an azimuth plane, and includes a first reflector panel having a first array of radiating elements mounted thereon and a second reflector panel having a second array of radiating elements mounted thereon, where the second reflector panel is rotatable with respect to the first reflector panel. Pursuant to the methods according to embodiments of the present invention, the second reflector panel is rotated with respect to the first reflector panel so that a first boresight pointing direction of the first reflector panel points in a different direction in the azimuth plane than does a second boresight pointing direction of the second reflector panel. First RF signals are fed from a first radio operated by a first cellular network operator to the first array. Second RF signals are fed from a second radio operated by a second cellular network operator that is different than the first cellular network operator to the second array. The first and second reflector panels may be in a vertically-stacked arrangement, and multiple arrays may be mounted on each reflector panel. The second sector may partially overlap the first sector but may not completely overlap the first sector. [0047] Base station antennas according to embodiments of the present invention will now be discussed in greater detail with reference to the attached figures. [0048] FIG.2 is a side view of a base station antenna 100 according to certain embodiments of the present invention. As shown in FIG.2, the base station antenna 100 includes an external housing 102. The external housing 102 may comprise, for example, a bottom end cap 104 a top end cap 106 and a radome 108. The radome 108 may be, for example, a tubular structure that has open bottom and top ends. The radome 108 may be formed, for example, of a dielectric material (e.g., fiberglass or a thermoplastic) that is substantially transparent to RF radiation in the operating frequency bands of the antenna 100. The bottom end cap 104 may cover the open bottom end of the radome 108 and the top end cap 106 may cover the open top end of the radome 108. The radome 108 may be mounted to the top and/or bottom end caps 104, 106 and/or to a fixed support structure that is described below. The base station antenna 100 also includes a plurality of RF connector ports 150 or "RF ports." The RF ports 150 may be mounted in the bottom end cap 104 in example embodiments. The RF ports 150 may be connected to external radios (not shown) via coaxial cables (not shown). [0049] FIG.3 is a schematic front view of the base station antenna 100 of FIG.2 with the radome 108 and various other components of the antenna omitted. As shown in FIG.3, the base station antenna 100 further includes a first reflector panel 110-1 and a second reflector panel 110-2 that are mounted inside the housing 102. The first and second reflector panels 110- 1, 110-2 are mounted in a vertically-stacked arrangement. One or more linear arrays of radiating elements may be mounted on each reflector panel 110. In the depicted embodiment, two linear arrays 120-1, 120-2 of low-band radiating elements 122 and two linear arrays 130-1, 130-2 of mid-band radiating elements 132 are mounted on the first reflector panel 110-1, while one additional linear array 120-3 of low-band radiating elements 122 and two additional linear arrays 130-3, 130-4 of mid-band radiating elements 132 are mounted on the second reflector panel 110- 2. Herein, the linear arrays 120 may be referred to as low-band linear arrays and the linear arrays 130 may be referred to as mid-band linear arrays. Each linear array 120, 130 may comprise a vertically-extending column of radiating elements (i.e., the radiating elements in each linear array 120, 130 extend in a substantially vertical direction when the base station antenna 100 is mounted for normal use). [0050] The low-band radiating elements 122 may, for example, be configured to operate in some or all of the 617-960 MHz frequency band, and the mid-band radiating elements 132 may, for example, be configured to operate in some or all of the 1427-2690 MHz frequency band. It will be appreciated, however, that embodiments of the present invention are not limited thereto. It will also be appreciated that the array configurations illustrated in FIG.3 are exemplary in nature, and that different types of arrays (including planar multi-column arrays), different combinations of arrays, different array layouts on the reflector panels and/or different numbers of radiating elements per array may be provided in other embodiments. In the depicted embodiment, each of the low-band radiating elements 122 and the mid-band radiating elements 132 are implemented as slant -45⁰/+45⁰ cross-dipole radiating elements that include a first dipole radiator that is configured to transmit and receive RF signals having a -45⁰ polarization, and a second dipole radiator that is configured to transmit and receive RF signals having a +45⁰ polarization, where each dipole radiator includes a pair of dipole arms, and the four dipole arms are arranged in a X-shaped configuration when viewed from the front. In the figures, the radiating elements 122, 132 will be represented by large X's consistent with the cross-dipole radiating element implementation. It will be appreciated that different types of radiating elements may be used in other embodiments, such as patch radiating elements. [0051] As noted above, the base station antenna 100 includes a plurality of RF ports 150. In the depicted embodiment, the base station antenna 100 includes a total of fourteen RF ports 150 (not all of which are visible in FIG.2), with two RF ports 150 connected to each of the seven linear arrays 120, 130 included in antenna 100. The first RF port 150 that is connected to each linear array 120, 130 is connected to the -45⁰ dipole radiators of the radiating elements 122, 132 in the linear array 120, 130, and the second RF port 150 that is connected to each linear array 120, 130 is connected to the +45⁰ dipole radiators of the radiating elements 122, 132 in the linear array 120, 130. The pair of RF ports 150 that are connected to each linear array 120, 130 may be connected to respective radios (not shown), that are typically mounted external to the antenna 100. The first cellular network operator operates the radios that are connected to the linear arrays 120-1, 120-2, 130-1, 130-2 that are mounted on the first reflector panel 110-1, and the second cellular network operator operates the radios that are connected to the linear arrays 120-3, 130-3, 130-4 that are mounted on the second reflector panel 110-2. [0052] The base station antenna 100 may further include a number of conventional components that are not depicted in FIGS.2-3, such as for example, phase shifters, remote electronic tilt ("RET") actuators, mechanical linkages and various cabling connections. [0053] At least one of the reflector panels 110-1, 110-2 can rotate independently about an axis 112 so that the reflector panel 110 rotates in the azimuth plane. The axis 112 may comprise a vertical axis. In some embodiments, both of the reflector panels 110-1, 110-2 can rotate independently. In such embodiments, it may be preferrable (but not required) to have both reflector panels 110 rotate about the same axis 112, as this may help minimize the size of the radome 108. In embodiments where only one reflector panel 110 can rotate (e.g., the second reflector panel 110-2), the antenna 100 can be mounted so that the boresight pointing direction for the fixed (non-rotatable) reflector panel 110-1 points in the desired direction in the azimuth plane for one of the cellular network operators, and the second reflector panel 110-2 can be rotated to point in the desired direction in the azimuth plane for the other of the cellular network operators. [0054] While only configuring one of the two reflector panels 110-1, 110-2 to be rotatable in the azimuth plane may reduce the cost and complexity of the base station antenna 100, there are also advantages to having both reflector panels 110-1, 110-2 have the ability to rotate in the azimuth plane. If both reflector panels 110-1, 110-2 are rotatable, then the installers who initially mount the antenna 100 need not exactly align the antenna 100 to point in a desired direction in the azimuth plane. Instead, each reflector panel 110-1, 110-2 may be rotated so that the boresight pointing direction thereof points in the desired direction in the azimuth plane after the antenna 100 has been installed. [0055] FIGS.4A and 4B are schematic top views of the base station antenna 100 that illustrate the second reflector panel 110-2 rotated to two different positions in the azimuth plane, In FIGS.4A and 4B, only the radome 108, the reflector panels 110, the linear arrays 120, 130, a fixed support structure 160, and a rotating member 170 are shown to simplify the drawings. As shown in FIG.4A, initially, both reflector panels 110-1, 110-2 may be oriented so that their boresight pointing directions are in the same direction in the azimuth plane. This arrangement may be appropriate when the base station antenna 100 is being used by a single cellular network operator or it is being used by two different cellular network operators, but in a location where the surrounding base stations for both cellular network operators are co-located. As shown in FIG.4B, if the base station antenna 100 is to be shared by two cellular network operators at a location where the surrounding base stations of the two cellular network operators are at different locations, then the second reflector panel 110-2 is rotated with respect to the first reflector panel 110-1 so that the first reflector panel 110-1 points in an appropriate direction to provide coverage to a sector of a cell of the first cellular network, and the second reflector panel 110-2 points in an appropriate direction to provide coverage to a sector of a cell of the second cellular network. While the second reflector panel 110-2 is depicted as being rotated about -30⁰ in the azimuth plane with respect to the first reflector panel 110-1, it will be appreciated that the second reflector panel 110-2 may be rotated any angle in the azimuth plane with respect to the first reflector panel 110-1. Typically, the boresight pointing direction in the azimuth plane of the first reflector panel 110-1 will be offset from the boresight pointing direction in the azimuth plane of the second reflector panel 110-2 by less than +/-60⁰. [0056] As noted above, the base station antenna 100 further includes a fixed support structure 160. The fixed support structure 160 may be configured to remain stationary with respect to a structure on which the base station antenna 100 is mounted (e.g., an antenna mount on an antenna tower). The fixed support structure 160 may comprise panels, brackets or any other support elements, and the particular configuration of the fixed support structure 160 is not important. Thus, the fixed support structure 160 is schematically shown in FIGS.4A-4B. In some embodiments, the fixed support structure 160 may include the bottom end cap 104 and/or the top end cap 106. [0057] One or both of the reflector panels 110-1, 110-2 may be rotatably mounted to the fixed support structure 160. For example, in some embodiments, reflector panel 110-1 may be rotatably mounted to the fixed support structure 160 while reflector panel 110-2 is fixedly mounted to the fixed support structure 160. In other embodiments, reflector panel 110-2 may be rotatably mounted to the fixed support structure 160 while reflector panel 110-1 is fixedly mounted to the fixed support structure 160. In still other embodiments, both reflector panels 110-1, 110-2 may be rotatably mounted to the fixed support structure 160. [0058] In some embodiments, the rotatable ones of the reflector panels 110 may be mounted so that the center of the reflector panel 110 is fixedly connected to a rotating member 170. The rotating member 170 may, for example, be rotatably mounted to the fixed support structure 160. The rotating member 170 may be rotated by hand or by a powered actuator. Rotation of the rotating member 170 causes the attached reflector panel 110 to rotate about its axis of rotation 112. It should be noted that the rotating member 170 may be affixed to the back of the reflector panel 110 or to the front of the reflector panel 110 in example embodiments. [0059] While the rotating member 170 is attached to the center of the reflector panel 110 in the above-described embodiments, it will be appreciated that embodiments of the present invention are not limited thereto, and that the rotating member 170 may be attached to any appropriate location on the reflector panel 110. For example, in other embodiments, the rotating member 170 may be attached at or near a side edge of the reflector panel 110. [0060] The rotating member 170 may comprise, for example, a cylindrical rod, although any appropriate rotating member 170 may be used. In some embodiments, the rotating member 170 may be formed of a non-metallic material such as fiberglass or a thermoplastic to reduce the risk of passive intermodulation ("PIM") distortion. [0061] In some embodiments, the base station antenna 100 may include an electric motor 180 such as, for example, a direct current ("DC") electric motor, that is used to rotate the reflector panels 110. If only one reflector panel 110 is rotatable, a single electric motor 180 may be provided. If both reflector panels 112 are rotatable, then a pair of electric motors may be provided. Alternatively, a single electric motor 180 may be provided, and a gear mechanism may allow the motor 180 to selectively rotate one of the two reflector panels 110-1, 110-2. [0062] In some embodiments, the one or more electric motors 180 may be mounted outside the radome 108. This may be advantageous because it may reduce the risk that metal components of the motor 180 generate PIM distortion that could negatively impact the RF performance of base station antenna 100, and may also reduce the risk of electromagnetic compatibility issues in the motor control. However, it will be appreciated that in other embodiments the electric motor(s) 180 may be mounted inside the radome 108. [0063] FIG.5A and 5B are azimuth plots of the antenna beams generated by the antenna of FIG.2 with the reflector panels positioned as shown in FIGS.4A and 4B, respectively. As shown in FIG.5A, when the boresight pointing directions in the azimuth plane of the first and second reflector panels 110-1, 110-2 are the same, then each low-band linear array 120 may generate a pair of antenna beams 124 (one at each polarization) that have a HPBW in the azimuth plane of about 65⁰ at the center frequency of the low-band operating frequency range. The "pointing direction" of each low-band antenna beam 124 in the azimuth plane may be the same for the antenna beams 124 generated by all three low-band linear arrays 120-1, 120-2, 120- 3, and hence only a single low-band antenna beam 124 is shown in FIG.5A. Similarly, each mid-band linear array 130 may generate a pair of antenna beams 134 that have a HPBW in the azimuth plane of about 65⁰ at the center frequency of the mid-band operating frequency range. The pointing direction of each mid-band antenna beam 134 in the azimuth plane may be the same for the antenna beams 134 generated by all four mid-band linear arrays 130-1, 130-2, 130- 3, 130-4, and hence only a single mid-band antenna beam 134 is shown in FIG.5A. As shown in FIG.5A, both the low-band antenna beams 124 and the mid-band antenna beams 134 are configured to provide good coverage to a 120⁰ sector in the azimuth plane, while preferably not spilling much energy into the two adjacent 120⁰ sectors. Due to differences in the designs of the low-band and mid-band radiating elements 122, 132, the low-band and mid-band antenna beams 124, 134 may have slightly different shapes. As shown, in many cases the azimuth beamwidth of the low-band antenna beams 124 may be slightly larger than the azimuth beamwidth of the mid-band antenna beams 134. It will be appreciated that the antenna beams 124, 134 are shown schematically in FIGS.5A-5B, and hence the sidelobes are not shown. [0064] Referring to FIG.5B, when the boresight pointing directions in the azimuth plane of the first and second reflector panels 110-1, 110-2 are offset by 30⁰, then the antenna beams 124 generated by the third low-band linear array 120-3 will be rotated by 30⁰ in the azimuth plane with respect to the antenna beams 124 generated by the first and second low-band linear arrays 120-1, 120-2. Similarly, the antenna beams 134 generated by the third and fourth mid-band linear arrays 130-3, 130-4 will be rotated by 30⁰ in the azimuth plane with respect to the antenna beams 134 generated by the first and second mid-band linear arrays 130-1, 130-2. The antenna beams 124, 134 may each have a fixed azimuth beamwidth that is designed to provide coverage throughout a sector of a cell of a cellular network. [0065] Thus, by rotating at least one of the first and second reflector panels 110-1, 110-2 so that the two reflector panels 110-1, 110-2 have different boresight pointing directions in the azimuth plane, the arrays 120, 130 mounted on the first reflector panel 110-1 are configured to generate first antenna beams 124, 134 that provide coverage to a first sector of a cell of a base station operated by a first cellular network operator, and the arrays 120, 130 mounted on the second reflector panel 110-2 are configured to generate second antenna beams 124, 134 that provide coverage to a second sector of a cell of a base station operated by a second cellular network operator. The first sector and the second sector have different azimuth boresight pointing directions from the base station antenna 100. In some cases, the first sector and the second sector may partially (but not completely) overlap, meaning that a portion of the first sector is also part of the second sector. The first and second sectors may each extend for about 120⁰ in the azimuth plane in some embodiments. The first and second sectors may each extend for about 90⁰ in the azimuth plane in other embodiments. [0066] FIG.6 is a schematic front view of the base station antenna 200 according to further embodiments of the present invention with the radome and various other components of the antenna omitted. As can be seen by comparing FIGS.3 and 6, the base station antenna 200 is very similar to the base station 100, with the only difference being that the two mid-band linear arrays 130-1, 130-2 that are mounted on the first reflector panel 110-1 of antenna 100 are omitted and replaced with a four column array 140 of high-band radiating elements 142 in antenna 200. Base station antenna 200 also includes four additional RF ports 150 so that each column of radiating elements on each of the reflector panels 110-1, 110-2 is fed by two RF ports 150. The high-band radiating elements 142 may be configured to operate in some or all of the 3300-4200 MHz frequency band in example embodiments. In other embodiments, the four column array 140 of high-band radiating elements 142 may be replaced with a four column array 130 of mid-band radiating elements 132. [0067] The four column array 140 (or 130) may comprise a beamforming array 140 that is fed by eight of the RF ports 150. The eight RF ports 150 that connect to the beamforming array 140 may be connected to eight ports on a beamforming radio (not shown). The beamforming radio may adjust the magnitudes and phases of sub-components of an RF signal that are passed to each column in array 140 so that the antenna beams generated by each column constructively combine to form a composite high-band antenna beam 144 that has a narrower beamwidth in the azimuth plane, and the antenna beam 144 may also be electronically scanned in the azimuth plane. The beamforming radio may be a time division duplex radio that can generate different-shaped antenna beams 144 on a time slot-by-time slot basis. While the generated high-band antenna beams 144 do not cover the entire sector served by the arrays 120- 1, 120-2, 140 on the first reflector panel 110-1, the beamforming radio can electronically scan the generated high-band antenna beams 144 to provide coverage anywhere within the sector. [0068] FIGS.7A and 7B are schematic back views illustrating example mechanical structures for providing one or more rotatable reflector panels in the base station antennas according to embodiments of the present invention. In each case, the mechanical structures are shown implemented in the base station 100 of FIGS.2-3 that is described above (with the radome 108 removed), so further description of portions of the base station antenna 100 other than the mechanical structures for rotating the reflector panels will be omitted. [0069] As shown in FIG.7A, one potential mechanical structure 300 for rotating the reflector panels comprises a first rod 310 that is disposed within a second hollow rod 320. The rods 310, 320 may have any appropriate horizontal cross-section such as a circular, square or rectangular horizontal cross-section. The first rod 310 is fixedly attached to a back surface of the first reflector panel 110-1, and the second rod 320 is fixedly attached to a back surface of the second reflector panel 110-2. While not shown in FIG.7A, the first and second rods 310, 320 may each be rotatably coupled to the support structure 160. The radiating elements 122, 132 are shown using dashed lines in FIG.7A since they are on the opposite side of the reflector panels 110-1, 110-2 and hence are not visible in the view of FIG.7A. A first electric motor 330-1 is provided, and a drive shaft 332-1 of the first electric motor 330-1 is attached to the first rod 310 so that rotation of the drive shaft 332-1 causes rotation of the first rod 310. Thus, the first electric motor 330-1 may be activated to directly rotate the first rod 310, which in turn rotates the first reflector panel 110-1 in the azimuth plane. [0070] A second electric motor 330-2 is provided, and a drive shaft 332-2 of the second electric motor 330-2 is attached to the second rod 320 via a mechanical linkage 334. The mechanical linkage 334 may comprise gears, shafts and other components that transfer rotational movement of the drive shaft 332-2 of the second electric motor 330-2 into rotational movement of the second rod 320. Thus, the second electric motor 330-1 may be activated to rotate the drive shaft 332-2 thereof which in turn through the mechanical linkage 334 rotates the second rod 320, thereby causing rotation of the second reflector panel 110-2 in the azimuth plane. [0071] While two electric motors 180 are shown in FIG.7A, it will be appreciated that in other embodiments a single electric motor 180 may be provided, and a gear system may also be provided that selectively connects the drive shaft of the electric motor 180 to one of the first rod 310 or the second rod 320 in order to rotate one of the respective first and second reflector panels 110-1, 110-2. [0072] As shown in FIG.7B, another potential mechanical structure 400 for rotating the reflector panels 110-1, 110-2 comprises a first rod 410 and a second rod 420. The first rod 410 is fixedly attached to the back surface of the first reflector panel 110-1, and the second rod 420 is fixedly attached to the back surface of the second reflector panel 110-2. The radiating elements 122, 132 are shown using dashed lines in FIG.7B since they are on the opposite side of the reflector panels 110-1, 110-2 and hence are not visible in the view of FIG.7B. A first electric motor 430-1 is provided, and a drive shaft 432-1 of the first electric motor 430-1 is attached to the first rod 410 so that rotation of the drive shaft 432-1 causes rotation of the first rod 410. Thus, the first electric motor 430-1 may be activated to directly rotate the first rod 410, which in turn rotates the first reflector panel 110-1 in the azimuth plane. The first motor 430-1 is mounted above the first reflector panel 110-1 in this embodiment. [0073] A second electric motor 430-2 is provided, and a drive shaft 432-2 of the second electric motor 430-2 is attached to the second rod 420 so that rotation of the drive shaft 432-2 causes rotation of the second rod 420. Thus, the second electric motor 430-2 may be activated to directly rotate the second rod 420, which in turn rotates the second reflector panel 110-2 in the azimuth plane. The second motor 430-2 is mounted below the second reflector panel 110-2. [0074] While the base station antenna 100 includes a cylindrical radome 108 (or, at least the front portion of the radome has a semi-cylindrical shape), it will be appreciated that embodiments of the present invention are not limited thereto. For example, FIGS.8A and 8B are schematic horizontal cross-sectional views of base station antennas according to further embodiments of the present invention that include differently-shaped radomes. [0075] As shown in FIG.8A, in some embodiments, the base station antennas according to embodiments of the present invention may have radomes 108A that have a substantially oval horizontal cross-section. This may advantageously decrease the dimension of the antenna in the front-to-back or "depth" direction. Since the rotatable reflector panels may be designed in some embodiments to not rotate more than +/-60⁰, the radome 108A may be used to reduce the overall volume of the base station antenna. As shown in FIG.8B, in other embodiments, radomes 108B may be provided that have a generally oval horizontal cross-section except along the back of the radome, which may have a different shape such as a flat back wall. The use of radome 108B may further reduce the volume of the base station antenna. Radomes having a variety of other shapes may be used. [0076] While the base stations according to embodiments of the present invention discussed above include a total of two vertically stacked reflector panels, it will be appreciated that embodiments of the present invention are not limited thereto. In other embodiments, base station antennas may include three or more vertically stacked reflector panels, where at least one and as many as all of the reflector panels are rotatable in the azimuth plane. [0077] FIG.9 is a flow chart diagram illustrating a method of operating a base station antenna according to certain embodiments of the present invention. The method illustrated in the flow chart of FIG.9 may be carried out using a base station antenna that has a longitudinal axis. The longitudinal axis may extend in a vertical direction when the base station antenna is mounted for use, and hence may extend generally perpendicular to the azimuth plane. The base station antenna includes a first reflector panel having a first array of radiating elements mounted thereon and a second reflector panel having a second array of radiating elements mounted thereon. The second reflector panel is rotatable with respect to the first reflector panel. [0078] As shown in FIG.9, pursuant to these methods, the second reflector panel is rotated with respect to the first reflector panel so that a first boresight pointing direction of the first reflector panel points in a different direction in the azimuth plane than does a second boresight pointing direction of the second reflector panel (Block 500). First RF signals from a first radio operated by a first cellular network operator are fed to the first array (Block 510). Second RF signals from a second radio operated by a second cellular network operator that is different than the first cellular network operator are fed to the second array (Block 520). [0079] Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. [0080] 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. [0081] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (i.e., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). [0082] References to "substantially" mean within +/-10% unless expressly defined otherwise. References to "about" mean within +/-5% unless expressly defined otherwise [0083] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. [0084] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" "comprising," "includes" and/or "including" when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof. [0085] Aspects and elements of all of the embodiments disclosed above can be combined in any way and/or combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.

Claims

That which is claimed is: 1. A base station antenna, comprising: a first reflector panel having a first array of radiating elements mounted thereon, the radiating elements of the first array arranged in at least one vertically-extending column; a second reflector panel having a second array of radiating elements mounted thereon; and a housing that includes a radome, the housing surrounding both the first reflector panel and the second reflector panel, wherein the first reflector panel and the second reflector panel are mounted in a vertically-stacked arrangement, wherein the second reflector panel is rotatable in an azimuth plane with respect to the first reflector panel so that the first array is configured to generate first antenna beams that provide coverage to a first sector and the second array is configured to generate second antenna beams that provide coverage to a second sector, and wherein the second sector partially overlaps the first sector but does not completely overlap the first sector.

2. The base station antenna of Claim 1, wherein the first antenna beams have fixed azimuth beamwidths that provide coverage to the first sector and the second antenna beams have fixed azimuth beamwidths that provide coverage to the second sector.

3. The base station antenna of Claim 1, wherein the first reflector panel is rotatable about a first axis.

4. The base station antenna of Claim 3, wherein the second reflector panel is rotatable about the first axis.

5. The base station antenna of Claim 3, wherein the second reflector panel is rotatable about a second axis that is not collinear with the first axis.

6. The base station antenna of any of Claims 1-5, wherein the second reflector panel is configured to rotate at least 30⁰ in the azimuth plane with respect to the first reflector panel.

7. The base station antenna of any of Claims 1-5, wherein the first sector extends for approximately 120⁰ in the azimuth plane and the second sector extends for approximately 120⁰ in the azimuth plane.

8. The base station antenna of any of Claims 1-5, further comprising at least one electric motor that is configured to rotate the first reflector panel and/or the second reflector panel.

9. The base station antenna of any of Claims 1-8, wherein the first sector is associated with a first cellular network operator and the second sector is associated with a second cellular network operator that is different than the first cellular network operator.

10. The base station antenna of any of Claims 1-9, wherein the first reflector panel is fixed with respect to the housing and the second reflector panel is rotatable with respect to the housing.

11. The base station antenna of any of Claims 1-5, wherein the second reflector panel is fixed with respect to the housing and the first reflector panel is rotatable with respect to the housing.

12. The base station antenna of any of Claims 1-5, wherein both the first reflector panel and the second reflector panel are rotatable with respect to the housing.

13. The base station antenna of any of Claims 1-12, further comprising a first rod that is fixedly attached to the first reflector panel and a second rod that is fixedly attached to the second reflector panel, where the first rod extends within an open interior of the second rod.

14. The base station antenna of any of Claims 1-13, further comprising a first electric motor that is configured to rotate the first reflector panel and a second electric motor that is configured to rotate the second reflector panel.

15. The base station antenna of any of Claims 1-14, further comprising a electric motor and a gear system that selectively couples an output shaft of the electric motor to a first rod that is connected to the first reflector panel and a second rod that is connected to the second reflector panel.

16. The base station antenna of any of Claims 1-15, wherein a front portion of the radome has a substantially semi-cylindrical shape.

17. The base station antenna of any of Claims 1-16, wherein the radiating elements of the first array are coupled to a first radio frequency ("RF") port, and the first RF port is coupled to a first radio, and the radiating elements of the second array are coupled to a second RF port, and the second RF port is coupled to a second radio.

18. The base station antenna of any of Claims 1-17, further comprising a support structure and a first rod that is rotatably coupled to the support structure.

19. The base station antenna of any of Claims 1-18, wherein the second array is a multi-column beamforming array that is configured to generate electronically scanned antenna beams that together provide coverage to the second sector.

20. A method of operating a base station antenna that has a longitudinal axis that extends generally perpendicular to an azimuth plane, the base station antenna including a first reflector panel having a first array of radiating elements mounted thereon and a second reflector panel having a second array of radiating elements mounted thereon, where the second reflector panel is rotatable with respect to the first reflector panel, the method comprising: rotating the second reflector panel with respect to the first reflector panel so that a first boresight pointing direction of the first reflector panel points in a different direction in the azimuth plane than does a second boresight pointing direction of the second reflector panel, feeding first radio frequency ("RF") signals from a first radio operated by a first cellular network operator to the first array; and feeding second RF signals from a second radio operated by a second cellular network operator that is different than the first cellular network operator to the second array.

21. The method of Claim 20, wherein the first reflector panel and the second reflector panel are mounted in a vertically-stacked arrangement.

22. The method of Claim 20, wherein the base station antenna further includes a housing that has a radome, the housing surrounding both the first reflector panel and the second reflector panel.

23. The method of any of Claims 20-22, wherein the first array generates first antenna beams in response to the first RF signals that provide coverage to a first sector that extends for approximately 120⁰ in the azimuth plane, and the second array generates second antenna beams in response to the second RF signals that provide coverage to a second sector that extends for approximately 120⁰ in the azimuth plane, where the second sector only partially overlaps the first sector in the azimuth plane.

24. The method of any of Claims 20-22, wherein the first RF signals generates first antenna beams that have fixed azimuth beamwidths so as to cover a first sector of a cell of a cellular network operated by the first cellular network operator, and the second RF signals generates second antenna beams that have fixed azimuth beamwidths so as to cover a second sector of a cell of a cellular network operated by the second cellular network operator.

25. The method of Claim 24, wherein the first sector partially overlaps the second sector.

26. The method of Claim 24, wherein the first sector extends for approximately 120⁰ in the azimuth plane and the second sector extends for approximately 120⁰ in the azimuth plane.

27. The method of any of Claims 20-26, wherein rotating the second reflector panel with respect to the first reflector panel comprises using an electric motor to rotate the second reflector panel with respect to the first reflector panel.

28. The method of any of Claims 20-27, wherein the first reflector panel is fixed with respect to a housing of the base station antenna and the second reflector panel is rotatable with respect to the housing.

29. The method of any of Claims 20-28, wherein the base station antenna includes a radome having a front portion that has a substantially semi-cylindrical shape.