Patent Publication Number: US-2023164883-A1

Title: Base station antenna units having arrays spanning multiple antennas that are connected by jumper cables

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 17/114,649, filed Dec. 8, 2020, which in turn claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 62/975,372, filed Feb. 12, 2020, and to U.S. Provisional Patent Application Ser. No. 62/949,709, filed Dec. 18, 2019, the entire content of each of the above applications is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention generally relates to radio communications and, more particularly, to base station antennas that support communications in multiple frequency bands. 
     Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells” which are served by respective base stations. The base station may include one or more antennas that are configured to provide two-way radio frequency (“RF”) communications with mobile subscribers that are within the cell served by the base station. In many cases, each cell is divided into “sectors.” Typically, the base station antennas are mounted on a tower or other raised structure, with the radiation patterns (also referred to herein as “antenna beams”) that are generated by the base station antennas directed outwardly. 
     A common base station configuration is the three sector configuration in which the cell is divided into three 120° sectors in the azimuth plane. A base station antenna is provided for each sector. In a three sector configuration, the antenna beams generated by each base station antenna typically have a Half Power Beamwidth (“HPBW”) in the azimuth (horizontal) plane of about 65° so that the antenna beams provide good coverage throughout a 120° sector. Typically, each base station antenna will include one or more vertically-extending columns of radiating elements that are typically referred to as “linear arrays.” Each radiating element may have a HPBW of approximately 65°. By providing a column of radiating elements extending along the elevation (vertical) plane, the elevation HPBW of the antenna beam may be narrowed to be significantly less than 65°, with the amount of narrowing increasing with the length of the column in the vertical direction. Typically, the radiating elements in a linear array are spaced apart from adjacent radiating elements at a fixed distance that is based on the operating frequency band of the radiating elements and performance requirements for the array. The number of radiating elements included in the linear array may then be selected so that the linear array will have a length that provides a desired elevation beamwidth. 
     The desired elevation beamwidth for a linear array of radiating elements will depend upon the size and geography of the cell in which the base station antenna is deployed. In order to meet cellular operator requirements, base station antenna manufacturers typically sell multiple versions of many base station antenna models that have different array lengths and hence elevation beamwidths. For example, in some cases, it may be desirable to have a small elevation beamwidth (e.g., 10-15 degrees) in order to increase the antenna gain and/or to reduce spillover of the antenna beam into adjacent cells (as such spillover appears as interference in the adjacent cells). This requires relatively long linear arrays. In other cases, larger elevation beamwidths are acceptable, allowing the use of shorter linear arrays that have fewer radiating elements. 
     In order to accommodate the increasing volume of cellular communications, new frequency bands are being made available for cellular service. Cellular operators now typically deploy multi-band base station antennas that include arrays of radiating elements that operate in different frequency bands to support service in these new frequency bands. For example, most base station antennas now include both “low-band” linear arrays of radiating elements that provide service in some or all of the 617-960 MHz frequency band and “mid-band” linear arrays of radiating elements that provide service in some or all of the 1427-2690 MHz frequency band. There is also interest in deploying base station antennas that include one or more arrays of “high-band” radiating elements that operate in higher frequency bands, such as some or all of the 3.3-4.2 GHz and/or the 5.1-5.8 GHz frequency bands. The high-band arrays are often implemented as multi-column arrays of radiating elements that can be configured to perform active beamforming where the shape of the antenna beam generated by the array can be controlled to form higher directivity antenna beams that support higher throughput. When beamforming arrays are used, a beamforming radio is often mounted directly on the back of the base station antenna in order to reduce RF losses. However, because the requirements for the beamforming antennas are more likely subject to change, and because beamforming antennas may experience higher failure rates, cellular operators may sometimes prefer that the beamforming antennas be implemented as separate antennas. 
     Unfortunately, there are various disadvantages associated with deploying additional base station antennas. First, a separate charge typically applies for each base station antenna mounted on an antenna tower, and hence increasing the number of antennas typically results in increased installation costs. Second, cellular operators often lease space on antenna towers, and there is typically a separate leasing charge for each item of equipment mounted on the antenna tower. Third, local ordinances and/or zoning regulations may limit the number of base station antennas that can be mounted on an antenna tower, and hence additional antenna towers may need to be erected if the number of base station antennas required exceeds the number permitted by the local zoning ordinances. 
     When shorter base station antennas are used, it may be possible to mount two base station antennas in a vertically stacked fashion so that the two base station antennas may appear as a single antenna. For example, as disclosed in U.S. Patent Publication No. 2019/0123426, the entire content of which is incorporated herein by reference, first and second base station antennas may be mounted together in a vertically stacked arrangement so that the composite base station antenna unit has the appearance of a single base station antenna. The first base station antenna may comprise a conventional dual-band base station antenna that includes low-band and mid-band arrays of radiating elements, and may have a height (i.e., the length of the antenna in the vertical direction that is perpendicular to the plane defined by the horizon when the antenna is mounted for use) may be, for example, in the range of about 1.0 meters to about 2.0 meters. The second base station antenna may comprise, for example, a beamforming antenna that operates in, for example, a portion of the 3.3-4.2 GHz or 5.1-5.8 GHz frequency bands. The height of the second base station antenna may be for example, less than about 1.0 meters. 
     SUMMARY 
     Pursuant to embodiments of the present invention, base station antenna units are provided that include a first base station antenna that comprises a first housing that includes a first radome and a top end cap, a second base station antenna that comprises a second housing that includes a second radome and a bottom end cap, a jumper cable that includes a first connector port that is mounted in one of the top end cap or the bottom end cap, and a second connector port that is configured to mate with the first connector port, the second connector port mounted in the other one of the top end cap or the bottom end cap. A first longitudinal axis of the first connector port extends in a vertical direction and a second longitudinal axis of the second connector port extends in the vertical direction. 
     In some embodiments, the first and second base station antennas may be mounted in a vertically stacked arrangement, and a bottommost surface of the second base station antenna may be within 1 inch of a topmost surface of the first base station antenna. 
     In some embodiments, the jumper cable may be a retractable jumper cable. In some embodiments, the retractable jumper cable may be one of a plurality of jumper cables, and each of the plurality of retractable jumper cables may include a respective cable and a respective first connector port, and the second connector port may be one of a plurality of second connector ports, and each of the retractable jumper cables may be configured to mate with a respective one of the second connector ports. Each of the plurality of retractable jumper cables may be mounted in either the top end cap or the bottom end cap, and each of the associated second connector ports may be mounted in the other one of the top end cap or the bottom end cap in some embodiments. In some embodiments, at least two of the first connector ports may be mounted in a common connector support that is moveable between a disconnected position and a connected position. The first connector ports may be push-pull connector ports in some embodiments. 
     In some embodiments, the top end cap may include a compartment that has a front wall and a pair of side walls, and the plurality of retractable jumper cables may be mounted in the compartment. The top end cap may also include a cover that forms a back wall of the compartment. The cover may comprise, for example., a sliding cover, a pivoting cover or a removable cover. 
     In some embodiments, the cables of the retractable jumper cables may be configured to retract inside one of the first housing and the second housing. In some embodiments, the bottom end cap may include a compartment that includes a front wall and a pair of side walls, and the plurality of retractable jumper cables are mounted in the compartment. The bottom end cap may further include a sliding cover, a pivoting cover or a removable cover that forms a back wall of the compartment. 
     In some embodiments, the second connector ports may extend into the compartment when the second base station antenna is vertically stacked on the first base station antenna. In some embodiments, a horizontal width of the first radome may be substantially the same as a horizontal width of the second radome. 
     In some embodiments, the first base station antenna may further include a first radio frequency (“RF”) port and a first array of radiating elements that are coupled to the first RF port and a second RF port and a first portion of a second array of radiating elements that are connected to the second RF port, and the second base station antenna may include a third RF port and a third array of radiating elements that are coupled to the first RF port, and a second portion of the second array of radiating elements. 
     In some embodiments, the base station antenna unit may further comprise a first array of first frequency band radiating elements that spans the first base station antenna and the second base station antenna, and a first phase shifter that is connected to each of the first frequency band radiating elements in the first array. The base station antenna unit may also include a second array of second frequency band radiating elements that spans the first base station antenna and the second base station antenna, and a second phase shifter that is connected to each of the second frequency band radiating elements in the second array. The base station antenna unit may further include a first diplexer in the first base station antenna and a second diplexer in the second base station antenna, where the first diplexer includes a first port that is coupled to the first phase shifter, a second port that is coupled to the second phase shifter, and a common port that is coupled to the second diplexer. The base station antenna unit may also include a second diplexer that includes a first port that is coupled to at least one of the first frequency band radiating elements in the second base station antenna, a second port that is coupled to at least one of the second frequency band radiating elements in the second base station antenna, and a common port that is coupled to the common port of the first diplexer. The first diplexer may be connected to the second diplexer via a jumper cable connection. 
     Pursuant to further embodiments of the present invention, base station antenna units are provided that include a first base station antenna that comprises a first housing that includes a first radome and a top end cap, a second base station antenna that comprises a second housing that includes a second radome and a bottom end cap, a retractable jumper cable that includes a first connector port that is mounted in one of the top end cap or the bottom end cap, and a second connector port that is configured to mate with the first connector port, the second connector port mounted in the other one of the top end cap or the bottom end cap. 
     In some embodiments, the first and second base station antennas may be mounted in a vertically stacked arrangement, and a bottom surface of the second base station antenna may be within 1 inch of a top surface of the first base station antenna. 
     In some embodiments, the retractable jumper cable may comprise one of a plurality of jumper cables, each of the plurality of retractable jumper cables including a respective cable and a respective first connector port, and the second connector port may comprise one of a plurality of second connector ports, and each of the retractable jumper cables may also be configured to mate with a respective one of the second connector ports. Each of the plurality of retractable jumper cables may be mounted in either the top end cap or the bottom end cap, and each of the associated second connector ports may be mounted in the other one of the top end cap or the bottom end cap. Moreover, at least two of the first connector ports may optionally be mounted in a common connector support that is moveable between a disconnected position and a connected position. 
     In some embodiments, the top end cap may include a compartment that has a front wall and a pair of side walls, and the plurality of retractable jumper cables may be mounted in the compartment. The top end cap may also include a cover that forms a back wall of the compartment. 
     In some embodiments, the cables of the retractable jumper cables may be configured to retract inside one of the first housing and the second housing. 
     In some embodiments, the bottom end cap may include a compartment, and the plurality of retractable jumper cables may be mounted in the compartment. In some embodiments, the second connector ports may extend into the compartment when the second base station antenna is vertically stacked on the first base station antenna. 
     In some embodiments, the first base station antenna may further include a first RF port and a first array of radiating elements that are coupled to the first RF port and a second RF port and a first portion of a second array of radiating elements that are connected to the second RF port, and the second base station antenna may further include a third RF port and a third array of radiating elements that are coupled to the first RF port, and a second portion of the second array of radiating elements. 
     In some embodiments, a longitudinal axis of the first connector port may extend in a vertical direction and a longitudinal axis of the second connector port may also extend in the vertical direction. 
     In some embodiments, the base station antenna unit may further include a first array of first frequency band radiating elements that spans the first base station antenna and the second base station antenna, a first phase shifter that is connected to each of the first frequency band radiating elements in the first array, a second array of second frequency band radiating elements that spans the first base station antenna and the second base station antenna, and a second phase shifter that is connected to each of the second frequency band radiating elements in the second array. Moreover, the base station antenna unit may also include a first diplexer in the first base station antenna and a second diplexer in the second base station antenna, where the first diplexer includes a first port that is coupled to the first phase shifter, a second port that is coupled to the second phase shifter, and a common port, and the second diplexer includes a first port that is coupled to at least one of the first frequency band radiating elements in the second base station antenna, a second port that is coupled to at least one of the second frequency band radiating elements in the second base station antenna, and a common port that is coupled to the common port of the first diplexer. 
     Pursuant to still further embodiments of the present invention, base station antenna assemblies are provided that include a first base station antenna that comprises a first housing that includes a first radome and a top end cap, a second base station antenna that comprises a second housing that includes a second radome and a bottom end cap, a plurality of jumper cables that each include a cable and a first connector port, each of the cables extending through one of the top end cap or the bottom end cap, a moveable connector support, wherein at least two of the first connector ports are mounted on and movable with the connector support, and a plurality of second connector ports that are configured to mate with respective ones of the first connector ports, the second connector ports mounted in the other one of the top end cap or the bottom end cap. 
     In some embodiments, the first and second base station antennas may be mounted in a vertically stacked arrangement, and where a longitudinal axis of each of the first connector ports may extend in a vertical direction and a longitudinal axis of each of the second connector ports may also extend in the vertical direction. 
     In some embodiments, the moveable connector support may be attached to one of the first base station antenna and the second base station antenna via at least two of the jumper cables. In some embodiments, each of the jumper cables may comprise a retractable jumper cable. 
     In some embodiments, the top end cap may include a compartment, and the plurality of retractable jumper cables may be mounted in the compartment. 
     In some embodiments, the cables of the retractable jumper cables may be configured to retract inside one the first housing. 
     In some embodiments, the second connector ports may extend into the compartment when the second base station antenna is vertically stacked on the first base station antenna. 
     In some embodiments, the first base station antenna may further include a first RF port and a first array of radiating elements that are coupled to the first RF port and a second RF port and a first portion of a second array of radiating elements that are connected to the second RF port, and the second base station antenna may include a third RF port and a third array of radiating elements that are coupled to the first RF port, and a second portion of the second array of radiating elements. 
     In some embodiments, the base station antenna unit may further include a first array of first frequency band radiating elements that spans the first base station antenna and the second base station antenna, a first phase shifter that is connected to each of the first frequency band radiating elements in the first array, a second array of second frequency band radiating elements that spans the first base station antenna and the second base station antenna, and a second phase shifter that is connected to each of the second frequency band radiating elements in the second array. In some embodiments, the base station antenna unit may further include a first diplexer in the first base station antenna and a second diplexer in the second base station antenna, where the first diplexer includes a first port that is coupled to the first phase shifter, a second port that is coupled to the second phase shifter, and a common port, and the second diplexer includes a first port that is coupled to at least one of the first frequency band radiating elements in the second base station antenna, a second port that is coupled to at least one of the second frequency band radiating elements in the second base station antenna, and a common port that is coupled to the common port of the first diplexer. 
     Pursuant to still further embodiments of the present invention, base station antenna units are provided that include a first base station antenna, a second base station antenna that is stacked above the first base station antenna, a first array of first frequency band radiating elements that spans the first base station antenna and the second base station antenna, a second array of second frequency band radiating elements that spans the first base station antenna and the second base station antenna, and a first diplexer that has a first frequency selective port that is coupled to a subset of the first frequency band radiating elements of the first array and a second frequency selective port that is coupled to a subset of the second frequency band radiating elements of the second array. 
     In some embodiments, the base station antenna unit may further include a first phase shifter that is coupled to each of the first frequency band radiating elements in the first array and a second phase shifter that is coupled to each of the second frequency band radiating elements in the second array. 
     In some embodiments, the base station antenna unit may further include a second diplexer that includes a first frequency selective port that is coupled to the first phase shifter, a second frequency selective port that is coupled to the first phase shifter, and a common port that is coupled to a common port of the first diplexer. 
     In some embodiments, the common port of the first diplexer may be connected to the common port of the second diplexer by a jumper cable. 
     In some embodiments, the jumper cable may extend between a top end cap of the first base station antenna and a bottom end cap of the second base station antenna. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a front view of a base station antenna unit according to embodiments of the present invention. 
         FIG.  2    is a side view of the base station antenna unit of  FIG.  1   . 
         FIG.  3    is a front view of the base station antenna unit of  FIG.  1    with the radomes of the base station antennas removed. 
         FIG.  4    is a schematic block diagram of the feed network for one of the low-band linear arrays included in the base station antenna of  FIG.  1   . 
         FIG.  5    is an enlarged partial rear view of the base station antenna unit of  FIG.  1    with the connector ports on the two antennas in an unconnected state. 
         FIG.  6    is an enlarged partial rear view of the base station antenna unit of  FIG.  1    with the connector ports on the two antennas in a connected state. 
         FIG.  7    is a perspective view of a bottom end cap of the upper base station antenna included in the base station antenna unit of  FIG.  1   . 
         FIG.  8    is a perspective view of a top end cap of the lower base station antenna included in the base station antenna unit of  FIG.  1   . 
         FIG.  9    is a perspective view of one of the rubber seals included in the top end cap of  FIG.  8   . 
         FIG.  10    is another enlarged partial rear view of the base station antenna unit of  FIG.  1   . 
         FIG.  11    is an enlarged partial rear view of the base station antenna unit of  FIG.  1    with a cover for the top end cap of the lower base station antenna in place. 
         FIG.  12    is a perspective view of the cover of  FIG.  11   . 
         FIGS.  13  and  14    are enlarged partial rear views of a base station antenna unit that is similar to the base station antenna unit of  FIG.  1    except that the jumper cables are non-retractable. 
         FIG.  15 A  is a schematic front view of a base station antenna unit according to embodiments of the present invention that includes diplexed connections between the first and second antennas. 
         FIG.  15 B  is a schematic block diagram that illustrates two of the RF connections between the first and second base station antennas of the base station antenna unit of  FIG.  15 A . 
         FIG.  16 A  is a schematic front view of a base station antenna unit that is a modified version of the base station antenna unit of  FIG.  15 A . 
         FIG.  16 B  is a schematic block diagram that illustrates two of the RF connections between the first and second base station antennas of the base station antenna unit of  FIG.  16 A . 
         FIG.  17    is a schematic front view of a base station antenna unit according to still further embodiments of the present invention. 
     
    
    
     Herein, when multiple like elements are present they may be referred to using a two part reference number. Such elements may be referred to individually by their full reference numeral, and may be referred to collectively by the first part of their reference numeral (i.e., the part prior to the hyphen). 
     DETAILED DESCRIPTION 
     As discussed above, it is known to vertically stack a first base station antenna that includes a high-band array on top of a conventional base station antenna that includes one or more low-band or mid-band arrays of radiating elements so that the two base station antennas appear as a single antenna unit. While this approach works fine if the low-band linear arrays have a relatively wide elevation beamwidth requirement, the antenna unit may become too long if the low-band linear arrays must have a relatively narrow elevation beamwidth, since this requirement increases the length of the conventional base station antenna, such that zoning regulations or aesthetic considerations may preclude vertically stacking the two base station antennas. 
     The present invention is directed to base station antenna units that include first and second base station antennas. The first base station antenna may include a portion of a first linear array of radiating elements and the second base station antenna may include a second array of radiating elements. A third array of radiating elements may span both the first and second base station antennas. RF connections may be provided between the first and second base station antennas that allow sub-components of RF feed signals for the third array that are input to the first antenna to be passed to the portion of the third array that is implemented in the second base station antenna. 
     Certain advantages in terms of reduced cost and/or enhanced performance may be achieved when the above-discussed first and second base station antennas are stacked vertically. However, when the antennas are vertically stacked, there may be challenges in providing RF connections between the two vertically stacked antennas. Conventionally, RF connector ports are located on the bottom end caps of base station antennas, as this protects against the ingress of water into the interior of the antenna through the connector ports and/or the openings for the connector ports in the bottom end cap. However, when the second base station is stacked directly (or almost directly) on top of the first base station antenna, it is not possible to mount the RF connector ports in a conventional fashion. Embodiments of the present invention provide techniques for providing RF connections between the first and second base station antennas that may be easy to install, aesthetically pleasing, and exhibit low insertion loss, while maintaining good sealing performance. 
     In particular, pursuant to some embodiments of the present invention, base station antenna assemblies are provided which include a first antenna that has a plurality of retractable jumper cables that are terminated with first connector ports and a second antenna that includes a plurality of second connector ports that are configured to mate with the first connector ports. The retractable jumper cables may be used to form a plurality of RF connections between the first base station antenna and the second base station antenna. 
     In some embodiments, the first base station antenna may be the lower of two base station antennas that are mounted in a vertically stacked arrangement, and the retractable jumper cables may be mounted in a top end cap of the first base station antenna. In such embodiments, the second connector ports may be mounted in the bottom end cap of the upper one of the two vertically stacked base station antennas. The upper surface of the top end cap of the first base station antenna may be recessed to form a compartment, and the end of each retractable jumper cable that includes the first connector port may extend from the interior of the first base station antenna into the compartment. The second connector ports of the second (upper) base station antenna may also extend though the recess in the upper surface of the top end cap of the first (lower) base station antenna and into the compartment. In other embodiments, the retractable jumper cables may be mounted in the bottom end cap of the upper one of the two vertically stacked base station antennas and the second connector ports may be mounted in the top end cap of the bottom one of the two vertically stacked base station antennas. 
     In some embodiments, the first connector ports may be mounted in a common connector support that is moveable between a disconnected position and a connected position. In such embodiments, the first connector ports may be push-pull connector ports that may be mated with the second connector ports by simply pushing the two connector ports together. The common connector support may allow an installer to connect all of the first connector ports to their corresponding second connector ports in a single operation, and may help reduce or prevent misconnections. 
     Pursuant to further embodiments of the present invention, base station antenna units are provided that include a first base station antenna and a second base station antenna that is stacked above the first base station antenna. These base station antenna units include a first array of first frequency band radiating elements that spans the first base station antenna and the second base station antenna and a second array of second frequency band radiating elements that also spans the first base station antenna and the second base station antenna. These antenna units further include a first diplexer that has a first frequency selective port that is coupled to a subset of the first frequency band radiating elements of the first array and a second frequency selective port that is coupled to a subset of the second frequency band radiating elements of the second array. 
     In some embodiments, the base station antenna units may further include a first phase shifter that is coupled to each of the first frequency band radiating elements in the first array and a second phase shifter that is coupled to each of the second frequency band radiating elements in the second array. The base station antenna units may also include a second diplexer that has a first frequency selective port that is coupled to the first phase shifter, a second frequency selective port that is coupled to the first phase shifter, and a common port that is coupled to a common port of the first diplexer. The common port of the first diplexer may be connected to the common port of the second diplexer by a jumper cable. In some embodiments, jumper cable may extend between a top end cap of the first base station antenna and a bottom end cap of the second base station antenna. 
     Embodiments of the present invention will now be described in further detail with reference to the attached figures. 
       FIGS.  1 - 17    illustrate a base station antenna unit  100  according to certain embodiments of the present invention. The base station antenna unit  100  includes a first base station antenna  200  and a second base station antenna  300 . In the description that follows, the base station antenna unit  100  will be described using terms that assume that the base station antennas  200 ,  300  are mounted on a tower or other structure with the longitudinal axis of each antenna  200 ,  300  extending along a vertical axis and the front surface of each antenna  200 ,  300  mounted opposite the tower. 
     Referring first to  FIGS.  1 - 2   , the base station antenna assembly  100  includes the first base station antenna  200  and the second base station antenna  300 . The second base station antenna  300  is mounted on top of the first base station antenna  200  so that the two antennas  200 ,  300  are in a vertically stacked arrangement. The second base station antenna  300  may be in direct contact with the first base station antenna  200  or may be separated from the first base station antenna by a small gap such as a gap that is less than six inches, less than four inches, less two inches, less than one inch, or less than one-half of an inch in various embodiments. The first and second base station antennas  200 ,  300  may each have the same width (or at least approximately the same width). As a result, the two base station antennas  200 ,  300  may appear as a single antenna when viewed from the front. 
     The first base station antenna  200  includes a housing  210  that includes a radome  212 , a bottom end cap  214  and a top end cap  220 . The radome  212  may extend around the entire circumference of the first base station antenna  200  to form a tube or may have a front wall and a pair of side walls that connect to a backplate of an internal frame of the first base station antenna  200 . The bottom end cap  214  and/or the top end cap  220  may be formed integrally with the radome, although more typically that are separate elements that are mated with the radome  212 . One or more mounting brackets  216  may be provided on the rear side of the first base station antenna  200  which may be used to mount the antenna  200  on, for example, an antenna tower. A plurality of RF connector ports  260  are mounted in the bottom end cap  214  that may be used to connect radio ports to the first base station antenna  200 . An antenna assembly  230 , which will be discussed in further detail with reference to  FIG.  3   , is mounted within the housing  210 . The antenna assembly  230  may be slidably inserted into the housing  210  before the bottom end cap  214  is attached to the radome  212 . The first base station antenna  200  is typically mounted in a vertical configuration (i.e., its longitudinal axis may be generally perpendicular to a plane defined by the horizon) when the antenna  200  is mounted for normal operation. 
     The second base station antenna  300  includes a housing  310  that comprises a radome  312 , a top end cap  314  and a bottom end cap  320 . The radome  312  may extend around the entire circumference of the second base station antenna  300  to form a tube or may have a front wall and a pair of side walls that connect to a backplate of an internal frame of the second base station antenna  300 . Either the top end cap  314  or the bottom end cap  320  may, in some embodiments, be formed integrally with the radome  312 . An antenna assembly  330 , which will be discussed in further detail with reference to  FIG.  3   , is mounted within the housing  310 . The antenna assembly  330  may be slidably inserted into the housing  310  before the bottom end cap  320  is attached to the radome  312 . A radio  302  is mounted on the back surface of the second base station antenna  300 . The radio  302  may be a beamforming radio in some embodiments. A plurality of blind mate RF connector ports (not visible) may be provided on the back surface of the second base station antenna  300  that are configured to mate with corresponding blind mate RF connector ports (not shown) on the front surface of radio  302  when the radio  302  is mounted on the second base station antenna  300 . Suitable means for mounting the radio  302  on the second base station antenna  300  and for implementing the RF connections between the radio  302  and the second base station antenna  300  are disclosed in PCT Application Ser. No. PCT/US2019/054661, the entire content of which is incorporated herein by reference as if set forth in its entirety. Mounting brackets  316  may be used to mount the radio  302  and the second base station antenna  300  on an antenna tower or other mounting structure. The second base station antenna  300  is also mounted in a vertical configuration. 
       FIG.  3    is a front view of the antenna unit  100  with the radomes  212 ,  312  of the first and second base station antennas  200 ,  300  removed. 
     As shown in  FIG.  3   , the antenna assembly  230  of the first base station antenna  200  includes a main backplane  232  that includes a generally flat, metallic surface and optional sidewalls. The backplane  232  may serve as both a structural component for the antenna assembly  230  and as a ground plane and reflector for the radiating elements mounted thereon. Various mechanical and electronic components of the antenna  200  (not visible in  FIG.  3   ) such as phase shifters, remote electronic tilt units, mechanical linkages, controllers, diplexers, and the like, may be mounted behind the backplane  232 . As these components are conventional, further description thereof will be omitted. 
     As is also shown in  FIG.  3   , the first base station antenna  200  includes portions of two linear arrays  240 - 1 ,  240 - 2  of low-band radiating elements  242  as well as four linear arrays  250 - 1  through  250 - 4  of mid-band radiating elements  252 . The low-band radiating elements  242  are mounted to extend forwardly from the backplane  232  and are mounted in two columns. Each low-band radiating element  242  is implemented as a slant +/−45° cross-dipole radiating element. The low-band radiating elements  242  may be configured to transmit and receive signals in a first frequency band such as, for example, the 617-960 MHz frequency range or a portion thereof (e.g., the 617-896 MHz frequency band, the 696-960 MHz frequency band, etc.). The mid-band radiating elements  252  may likewise be mounted to extend forwardly from the backplane  232  and are mounted in four columns to form the four linear arrays  250 - 1  through  250 - 4 . Linear arrays  250 - 1  and  250 - 4  extend along the respective side edges of the backplane  232  while linear arrays  250 - 2 ,  250 - 3  extend down the center of the backplane  232 . The mid-band radiating elements  252  may be configured to transmit and receive signals in a second frequency band. Such as, for example, the 1427-2690 MHz frequency range or a portion thereof (e.g., the 1710-2200 MHz frequency band, the 2300-2690 MHz frequency band, etc.). Low-band array  240 - 1  extends between mid-band arrays  250 - 1  and  250 - 2 , and low-band array  240 - 2  extends between mid-band arrays  250 - 3  and  250 - 4 , 
     As is further shown in  FIG.  3   , the antenna assembly  330  of the second base station antenna  300  includes a main backplane  332  that includes a generally flat, metallic surface and optional sidewalls. The backplane  332  may serve as both a structural component for the antenna assembly  330  and as a ground plane and reflector for the radiating elements mounted thereon. Various mechanical and electronic components of the second base station antenna  300  (not visible in  FIG.  3   ) such as phase shifters, remote electronic tilt units, mechanical linkages, controllers, diplexers, and the like, may be mounted behind the backplane  332 . 
     As is also shown in  FIG.  3   , the second base station antenna  300  includes the remaining portions of the two linear arrays  240 - 1 ,  240 - 2  of low-band radiating elements  242  as well as a planar, eight-column array  350  of high-band radiating elements  352 . The low-band radiating elements  242  are mounted to extend forwardly from the backplane  332  and are mounted in two columns. The low-band radiating elements  242  may be identical to the low-band radiating elements  242  included in the first base station antenna  200 , and hence further description thereof will be omitted. The high-band radiating elements  352  are mounted to extend forwardly from the backplane  332  and are arranged in eight columns to operate as a beamforming array. The high-band radiating elements  352  may be configured to transmit and receive signals in a third frequency band such as, for example, the 3300-4200 MHz frequency range or a portion thereof. 
     As can also be seen in  FIG.  3   , the low-band radiating elements  242  are mounted on feedboards  244 . For example, in linear array  240 - 1 , low-band radiating elements  242 - 1  and  242 - 2  are mounted on a first feedboard  244 - 1 , low-band radiating elements  242 - 3  and  242 - 4  are mounted on a second feedboard  244 - 2 , and low-band radiating element  242 - 5  is mounted on a third feedboard  244 - 3 . Each feedboard  244  couples an RF signal input thereto to the one or more radiating elements  242  that are mounted on the feedboard  244 . Thus, for example, feedboard  244 - 1  splits an RF signal input thereto into two sub-components and couples the two sub-components of the RF signal to the respective radiating elements  242 - 1 ,  242 - 2 . A feedboard  244  that only includes a single radiating element  242  may couple the entirety of the RF signals input thereto to the radiating element  242  mounted thereon. 
     As shown in  FIG.  3   , each linear array  240 - 1 ,  240 - 2  of low-band radiating elements  242  extends across or “spans” both the first base station antenna  200  and the second base station antenna  300 . The RF connector ports  260  that feed signals to the low-band linear arrays  240 - 1 ,  240 - 2  are mounted in the bottom end cap  214  of the first base station antenna  200 . In particular, first and second RF connector ports  260 - 1 ,  260 - 2  are provided that feed first and second RF signals to the respective +45° and −45° radiators of the cross-polarized low-band radiating elements  242  of linear array  240 - 1  (one RF connector port  260  for each polarization), and third and fourth RF connector ports  260 - 3 ,  260 - 4  are provided that feed first and second RF signals to the respective +45° and −45° radiators of the cross-polarized low-band radiating elements  242  of linear array  240 - 2  (again, one RF connector port  260  for each polarization). 
     While the radiating elements in each of the low-band linear arrays  240  and the mid-band linear arrays  250  are all aligned along respective vertical axes, it will be appreciated that the term “linear array” as used herein includes staggered linear arrays in which some of the radiating elements are staggered in the horizontal direction with respect to other of the radiating elements so that the radiating elements do not extend perfectly along a vertical axis. 
       FIG.  4    is a block diagram that schematically illustrates the feed network  270  for first polarization RF signals (e.g., +45° polarization RF signals) for low-band linear array  240 - 1 . It will be appreciated that identical feed networks may be used for the second polarization RF signals fed to linear array  240 - 1  and for the first and second polarization RF signals that are fed to linear array  240 - 2 . 
     As shown in  FIG.  4   , RF connector port  260 - 1  of the first base station antenna  200  is connected (e.g., by a coaxial cable  272 ) to a phase shifter/power divider unit  274 . The phase shifter/power divider unit  274  splits the RF signal into five sub-components and applies a phase taper across those sub-components that is based on a setting of the phase shifter power/divider unit  274 , as is well known to those of ordinary skill in the art. The phase taper (if any) that is applied may be used to electronically change the elevation or “tilt” angle of the antenna beam formed by the first polarization radiators of the radiating elements  242  of linear array  240 - 1 . Three of the outputs of the phase shifter/power divider unit  274  are connected by coaxial feed cables  276  to the three feedboards  244  for linear array  240 - 1  that are included in the first base station antenna  200 . A total of five low-band radiating elements  242  are mounted on these three feedboards  244 , namely low-band radiating elements  240 - 1  and  240 - 2  are mounted on feedboard  244 - 1 , low-band radiating elements  240 - 3  and  240 - 4  are mounted on feedboard  244 - 2 , and low-band radiating element  240 - 5  is mounted on feedboard  244 - 3 . 
     As is further shown in  FIG.  4   , the remaining two outputs of phase shifter/power divider unit  274  are connected (either directly or indirectly) to coaxial jumper cables  280 . Each coaxial jumper cable  280  includes at least a cable  282  and an RF connector port  284  that is mounted on an end of the cable  282  that is opposite the phase shifter/power divider unit  274 . A pair of RF connector ports  360 - 1 ,  360 - 2  are provided on the second base station antenna  300  that are configured to mate with RF connector ports  284  provided on the coaxial jumper cables  280 . RF connector ports  360 - 1 ,  360 - 2  are connected by coaxial feed cables  362  to the two feedboards  244  for linear array  240 - 1  that are included in the second base station antenna  300 . A total of three low-band radiating elements  242  are mounted on these two feedboards  244 , namely low-band radiating elements  240 - 6  and  240 - 7  are mounted on feedboard  244 - 4 , and low-band radiating element  240 - 8  is mounted on feedboard  244 - 5 . 
     The first base station antenna  200  includes eight additional RF connector ports  260  that are connected to the mid-band linear arrays (two RF connector ports are connected to each linear array, one for each polarization) to pass RF signals between the mid-band linear arrays  250  and associated radios. These RF connector ports  260  and the feed networks connecting these RF connector ports  260  to the respective mid-band linear arrays  250  may be conventional, and hence further description thereof will be omitted here. Likewise, the second base station antenna  300  includes sixteen additional RF connector ports (not shown) that are connected to the high-band array  350  (two RF connector ports are connected to each column of the eight-column array, one for each polarization) to pass RF signals between the high-band array  350  and radio  302 . These RF connector ports and the feed networks connecting these RF connector ports to the respective arrays may have, for example, any of the designs shown in PCT Application Ser. No. PCT/US2019/054661, and hence further description thereof will be omitted here. 
     It will be appreciated that  FIGS.  1 - 4    illustrate one example of a base station antenna unit according to embodiments of the present invention, and that many modifications may be made thereto. For example, in other embodiments, the number of low-band, mid-band and high-band arrays may be varied from what is shown (including omitting certain types of arrays), as may the number of radiating elements included in each array. Likewise, different arrays may span the two base station antennas and/or the arrays may be arranged differently from what is shown. While the radiating elements are illustrated as being dual-polarized radiating elements in the depicted embodiment, it will be appreciated that in other embodiments some or all of the dual-polarized radiating elements may be replaced with single-polarized radiating elements. It will also be appreciated that while the radiating elements are illustrated as dipole radiating elements in the depicted embodiment, other types of radiating elements such as, for example, patch radiating elements may be used in other embodiments. 
     As discussed above, linear arrays  240 - 1 ,  240 - 2  span both the first and second base station antennas  200 ,  300 , and hence RF connections  110  are provided between the first and second base station antennas  200 ,  300  in the form of coaxial jumper cables  280  on the first base station antenna  200  and RF connector ports  360  on the second base station antenna  300 .  FIGS.  5 - 12    illustrate one example embodiment of these RF connections  110  and associated structures that protect these RF connections  110  from the elements. 
       FIGS.  5  and  6    are enlarged partial rear views of the antenna unit  100  that illustrate the interface between the first base station antenna  200  and the second base station antenna  300 . As shown in  FIGS.  5 - 6   , the second base station antenna  300  may be mounted directly on top of the first base station antenna  200 . The bottom end cap  320  of the second base station antenna  300  includes a plurality of connector ports  360  mounted therein. Each connector port  360  may extend along a respective longitudinal axis. In the depicted embodiment, all of these longitudinal axes extend in the vertical direction.  FIG.  7    is a perspective view of the bottom end cap  320  of the second base station antenna  300 . As can be seen, the bottom end cap  320  may have a conventional design and includes eight openings  322  that receive the respective RF connectors  360 . 
       FIG.  8    is a perspective view of the top end cap  220  of the first base station antenna  200 . As shown in  FIG.  8   , the top end cap  220  may have a non-conventional design. In particular, top end cap  220  has a planar top surface  221  with a downwardly extending lip  222 . The planar top surface  221  is recessed to form a compartment  223  that is defined between a pair of side walls  224 , a front wall  225  and a floor  226 . The rear of the compartment  223  may be left open to allow access to the interior of the compartment  223 . A plurality of openings  227  are formed in the floor  226  of compartment  223 . Rubber seals  228  that each include an access hole  229  are mounted in the respective openings  227 .  FIG.  9    is an enlarged perspective view of one of the rubber seals  228 . As shown in  FIG.  9   . each rubber seal  228  includes a downwardly protruding column  228   c  that is received within one of the openings  227  in the floor  226  of the compartment  223  in the top end cap  220 . The top portion of rubber seal  228  takes the form of a raised lip  228   l  that raises the upper part of access hole  229  above the floor  226  of compartment  223 . As such, even if a small amount of water gains access to compartment  223  and pools on the floor  226 , the raised lip  228   l  may prevent the water from entering into the access hole  229 . 
     In some embodiments, the openings  227  in the floor  226  of compartment  223  may be angled with respect to the vertical. This angling may be useful when retractable jumper cables  280  are used, as the angle may help initiate the bending of the cables  282  that occurs when the cables  292  are retracted backwardly into the antenna  200 . 
     Referring to  FIGS.  5  and  10   , it can be seen that the cables  282  of the coaxial jumper cables  280  are routed through the rubber seals  228  in the respective openings  227  so that the RF connector ports  284  are external to the housing  210 . In some embodiments, the RF connector ports  284  may be mounted in a common moveable connector support  290  that includes mounting locations for each RF connector port  284 . In the depicted embodiment, the connector support  290  is implemented as a plastic plate that includes openings for each cable  282  and screw holes (not visible) that allow each RF connector port  284  to be mounted onto the connector support  290  via small screws. These mounting locations may be positioned so that each RF connector port  284  may be aligned with a respective one of the RF connector ports  360  in the bottom end cap  320  of the second base station antenna  300 . The RF connector ports  284  may be push-in connector ports that are configured to mate with the respective RF connector ports  360 . As shown in  FIG.  6   , the connector support  290  may be moved upwardly in order to mate each RF connector port  284  with a respective one of the RF connector ports  360  in order to implement the RF connections  110  between the first and second base station antennas  200 ,  300 . One or more latches (not shown) or other locking mechanisms may be included that hold the connector support  290  in place in the position shown in  FIG.  6   . The connector support  290  allows an installer to connect all eight RF connector ports  284  to the mating RF connector ports  360  in a single operation, and also ensures that each RF connector port  284  is connected to its corresponding RF connector port  360  (i.e., misconnections are prevented). 
     In some embodiments, the coaxial jumper cables may be retractable jumper cables so that the cables  280  may move with respect to the openings  227  in the floor  226  of compartment  223 . In embodiments where the jumper cables  280  are retractable jumper cables  280 , the cables  282  may be still be fixed to the housing  210  or other internal structures of the first base station antenna  200  to ensure that an installer cannot pull the cables  282  to far out of the antenna  200  such that the internal ends of one or more of the cables  282  are pulled loose from the structures that they are connected to. In many cases, the internal end of each jumper cable  280  may be soldered to an output port on a phase shifter  274 , and fixing the cables  282  internally so that force cannot be transferred to these solder joints may help maintain the integrity of the solder joints. 
     In other embodiments, the cables  280  may be fixed to the housing  210  so that a pre-selected length of each cable  282  extends through the openings  227  in the top end cap  220 . This pre-selected length may include sufficient slack so that the connector support  290  may be moved from the position shown in  FIG.  5    to the position shown in  FIG.  6   .  FIGS.  13  and  14    are enlarged partial rear views of a base station antenna unit  100 ′ that is similar to the base station antenna unit  100  except that the jumper cables  280  are non-retractable jumper cables. As shown in  FIG.  13   , when the RF connector ports  284  are in a disconnected state, slack loops  286  may appear in the cables  282 . As shown in  FIG.  14   , when the jumper cables  280  are fully extended so that the RF connector ports  284  thereof mate with the corresponding RF connector ports  360  on the second base station antenna  300 , the slack loops  286  may substantially disappear. 
     Referring to  FIGS.  11  and  12   , a cover  292  may be provided that forms a rear wall for the compartment  223 . The cover  292  may be a separate removable cover, a hinged cover, a sliding cover or the like. The cover  292  may protect the RF connections  110  from the elements and may also reduce or prevent the ingress of water into the compartment  223 . While not shown in the drawings, a seal such as a rubber gasket may also be provided between the bottom end cap  320  of the second base station antenna  300  and the top end cap  220  of the first base station antenna  200 . 
     The above-described design of the RF connections  110  between the first and second base station antennas  200 ,  300  may have a number of advantages. First, the RF connector ports  360  extend downwardly from the bottom end cap  320  of the second base station antenna  300 . This design helps protect the second base station antenna  300  from water ingress through the RF connector ports  360  and may shield the RF connector ports  360  from rain. Second, by mounting the RF connector ports  284 ,  360  on the respective top and bottom end caps, the length of the RF connections  110  between the first and second base station antennas  200 ,  300  can be kept very short, which reduces the insertion losses along the RF connections. Since the array  350  operates at high frequencies, insertion losses can be quite high, and hence having short RF connections can provide a significant performance improvement (e.g., as much as a 2-3 dB improvement in insertion loss). Third, by mounting the RF connector ports  284  in a common connector support  290  and implementing the RF connector ports  284 ,  360  using push-in connectors, an installer can readily make all eight RF connections  110  in a single operation and can do so without misconnections. Fourth, the cover  292  may protect the RF connector ports  284 ,  360  and may shield the RF connections  110  from view. 
     It will be appreciated that the present invention may be modified in many different ways. For example, in some embodiments, the top end cap  220  of the first base station antenna  200  may be used instead (with appropriate modifications) as the bottom end cap of the second base station antenna  300 , and the bottom end cap  320  of the second base station antenna  300  may be used (with appropriate modifications) as the top end cap of the first base station antenna  200 . In such embodiments, the RF connector ports  360  would be mounted in the top end cap of the first base station antenna  200  and the coaxial jumper cables  280  would be mounted in the bottom end cap of the second base station antenna  300 . Such embodiments are fully within the scope of the present invention. 
     In some situations, it may be advantageous to have additional antenna arrays that extend between the first antenna and the second antenna of the base station antenna units according to embodiments of the present invention. As discussed above, in some example embodiments of the present invention, two low-band arrays  240 - 1 ,  240 - 2  span both the first and second antennas  200 ,  300 . For example, as shown in  FIGS.  3 - 4   , in one embodiment, four phase cable connections extend between the first and second antennas  200 ,  300  for low-band array  240 - 1 , namely a first phase cable connection for the +45° dipole radiators of radiating elements  242 - 6  and  242 - 7 , a second phase cable connection for the +45° dipole radiator of radiating element  242 - 8 , a third phase cable connection for the −45° dipole radiators of radiating elements  242 - 6  and  242 - 7 , and a fourth phase cable connection for the −45° dipole radiator of radiating element  242 - 8 . A phase cable connection refers to a connection between an output of a phase shifter/power divider and one or more radiating elements. Four additional phase cable connections similarly extend between the first and second antennas  200 ,  300  for low-band array  240 - 2 . Thus, a total of eight RF connections are provided between the first and second antennas  200 ,  300  in the base station antenna unit  100  of  FIGS.  3 - 4   . 
     Due to space constraints, it may be difficult to include substantially more than eight RF connections between the first and second antennas  200 ,  300  in some base station antenna designs. Reducing the number of RF connections between the first and second antennas  200 ,  300  may also be desirable as it reduces the chance for connection errors. However, applications exist where it would be beneficial to have additional arrays span the first and second antennas  200 ,  300  such as, for example, having some or all of the mid-band arrays  250 - 1  through  250 - 4  that are included in base station antenna unit  100  span both the first and second antennas  200 ,  300 . 
     Pursuant to further embodiments of the present invention, diplexers (note that the term “diplexer” is used broadly herein to encompass devices that filter/combine signals across two or more frequency bands, and hence encompasses, for example, triplexers) may be added to both the first and second antennas  200 ,  300  in order to allow the RF connections  110  that extend between the two antennas  200 ,  300  to carry, for example, both low-band and mid-band RF signals. In this way, the RF connections  110  may be used to pass both low-band and mid-band RF signals between the first and second antennas  200 ,  300 , thereby effectively doubling the number of actual RF transmission paths without increasing the number of RF connections  110 . 
       FIG.  15 A  is a schematic front view of a base station antenna unit  400  according to embodiments of the present invention (with the radome removed) that includes such a design. As shown in  FIG.  15 A , the base station antenna unit  400  is similar to the base station antenna unit  100  that is discussed above with reference to  FIGS.  1 - 14   . In particular, the base station antenna unit  400  includes a first base station antenna  500  and a second base station antenna  600 . The antenna assembly of the first base station antenna  500  includes a backplane  232  that may serve at least as a ground plane and reflector for the radiating elements mounted thereon. The first base station antenna  500  also includes portions of two linear arrays  240 - 1 ,  240 - 2  of low-band radiating elements  242  that may be identical to the like-numbered arrays  240  of low-band radiating elements  242  that are included in base station antenna unit  100 , and hence further description thereof will be omitted. The low-band radiating elements  242  may be mounted on feed boards (not shown in  FIG.  15 A ) in the exact same manner as discussed above with reference to the feed boards  244  of  FIG.  3   . The first base station antenna  500  further includes portions of four linear arrays  550 - 1  through  550 - 4  of mid-band radiating elements  252 . The mid-band radiating elements  252  are mounted to extend forwardly from the backplane  232 . The mid-band linear arrays  550 - 1  through  550 - 4  are similar to the mid-band linear arrays  250 - 1  through  250 - 4  that are included in base station antenna unit  100 , discussed above, except that mid-band linear arrays  550 - 1  through  550 - 4  each include two additional mid-band radiating elements  252  that are included in the second base station antenna  600 . In other words, base station antenna unit  400  differs from base station antenna unit  100  in that the four linear arrays  550 - 1  through  550 - 4  of mid-band radiating elements  252  each span both the first and second antennas  500 ,  600  in base station antenna unit  400 . Otherwise, the four linear arrays  550 - 1  through  550 - 4  of mid-band radiating elements  252  may be identical to the four linear arrays  250 - 1  through  250 - 4  of mid-band radiating elements  252  discussed above with reference to base station antenna unit  100 . 
     The second base station antenna  600  includes a main backplane  332  that serves at least as a ground plane and reflector for the radiating elements mounted thereon. As is shown in  FIG.  15 A , the second base station antenna  600  includes the remaining portions of the two linear arrays  240 - 1 ,  240 - 2  of low-band radiating elements  242 , the remaining portions of the four linear arrays  550 - 1  through  550 - 4  of mid-band radiating elements  252 , and a planar, eight-column array  350  of high-band radiating elements  352 . The planar, eight-column array  350  of high-band radiating elements  352  may be identical to the like-numbered high-band array  350  included in base station antenna unit  100 , and hence further description thereof will be omitted. The eight-column array  350  of high-band radiating elements  352  is shown schematically as a box in  FIG.  15 A  in order to simplify the drawing. 
     Each low-band linear array  240 - 1 ,  240 - 2  of low-band radiating elements  242  extends across or “spans” both the first base station antenna  500  and the second base station antenna  600 , and each mid-band linear array  550 - 1  through  550 - 4  of mid-band radiating elements  252  likewise spans both the first base station antenna  500  and the second base station antenna  600 . A total of two mid-band radiating elements  252  of each linear array  550 - 1  through  550 - 4  are included in the second base station antenna  600 , and in each linear array  550  both radiating elements  252  are mounted on a common feed board  254  and are configured to both be fed by common feed signals. Accordingly, a total of eight RF connections are needed between the first base station antenna  500  and the second base station antenna  600  to pass RF signals to and from the mid-band radiating elements  252 , namely one RF connection for each of the four mid-band arrays  550  for each of two polarizations. 
     In base station antenna unit  400 , a total of eight RF connections  110  are provided between the first base station antenna  500  and the second base station antenna  600 , yet a total of sixteen RF connections are required (eight for the low-band arrays  240  and eight for the mid-band arrays  550 ). In order to implement sixteen RF connections over the eight physical RF connections  110 , pursuant to embodiments of the present invention, each RF connection is diplexed so that it may act as both a low-band RF transmission path and as a mid-band RF transmission path. This is shown in more detail with reference to  FIG.  15 B , which is a schematic block diagram depicting certain of the elements of the base station antenna unit  400 . 
     As shown in  FIG.  15 B , the phase shifters  574  for the low-band arrays  240 - 1 ,  240 - 2  and the phase shifters  576  for the mid-band arrays  550 - 1  through  550 - 4  are mounted in the first base station antenna  500 . While only one low-band phase shifter  574  and two mid-band phase shifters  576  are shown in  FIG.  15 B , it will be appreciated that a total of four low-band phase shifters  574  and eight mid-band phase shifters  576  may be provided, namely two phase shifters  574  (one for each polarization) for each low-band array  240  and two phase shifters  576  for each mid-band linear array  550 . 
     A first RF port  560 - 1  on the first base station antenna  500  is coupled to an input port of the low-band phase shifter  574 . The low-band phase shifter  574  may split RF signals input thereto into a plurality of sub-components, and may apply a phase taper to the sub-components in order to electrically change the elevation or “tilt” angle of the antenna beam generated by low-band linear array  240 - 1 , in a manner well understood by those of skill in the art. In the depicted embodiment, the low-band phase shifter  574  divides RF signals input thereto from the first RF port  560 - 1  into five sub-components that are output at the respective five outputs of the low-band phase shifter  574 . As shown in  FIG.  15 B , three of the outputs of low-band phase shifter  574  are coupled to low-band radiating elements  242  of the first low-band array  240 - 1  that are mounted in base station antenna  500 , in the exact same manner as is shown in  FIG.  4    above. As is further shown in  FIG.  15 B , the fourth output of low-band phase shifter  574  is connected to a first frequency selective port of a first diplexer  590 - 1  that is mounted in the first base station antenna  500  and the fifth output of low-band phase shifter  574  is connected to a first frequency selective port of a second diplexer  590 - 2  that is mounted in the first base station antenna  500 . 
     A second RF port  560 - 2  included on the first base station antenna  500  is coupled to an input port of the first mid-band phase shifter  576 - 1 . The first mid-band phase shifter  576 - 1  may split RF signals input thereto into a plurality of sub-components, and may apply a phase taper to the sub-components in order to electrically change the elevation or “tilt” angle of the antenna beam generated by mid-band linear array  550 - 1 . In the depicted embodiment, the first mid-band phase shifter  576 - 1  divides RF signals input thereto into seven sub-components that are output at the respective seven outputs of the phase shifter  576 - 1 . Six of the outputs may be coupled to the twelve mid-band radiating elements  252  in the first mid-band array  550 - 1  (each output feeds two mid-band radiating elements  252 ). The seventh output is connected to a second frequency selective port of the first diplexer  590 - 1 . 
     A third RF port  560 - 3  on the first base station antenna  500  is coupled to an input port of the second mid-band phase shifter  576 - 2 . The second mid-band phase shifter  576 - 2  may split RF signals input thereto into a plurality of sub-components, and may apply a phase taper to the sub-components in order to electrically change the elevation or “tilt” angle of the antenna beam generated by mid-band linear array  550 - 2 . In the depicted embodiment, the second mid-band phase shifter  576 - 2  divides RF signals input thereto into seven sub-components that are output at the respective seven outputs of the phase shifter  576 - 2 . Six of the outputs are coupled to the twelve mid-band radiating elements  252  in the second mid-band array  550 - 2  (each output feeds two mid-band radiating elements  252 ). The seventh output is connected to a second frequency selective port of the second diplexer  590 - 2 . 
     The common port of the first diplexer  590 - 1  is coupled to a first RF connector port  584 - 1  and the common port of the second diplexer  590 - 2  is coupled to a second RF connector port  584 - 2 . A first coaxial jumper cable (not shown) connects the first RF connector port  584 - 1  to a first RF connector port  360 - 1  on the second base station antenna  600 , and a second coaxial jumper cable (not shown) connects the second RF connector port  584 - 2  to a second RF connector port  360 - 2  on the second base station antenna  600 . The coaxial jumper cables may be any of the coaxial jumper cables disclosed herein, including the retractable coaxial jumper cables that include the connector ports  584  that are described, for example, with reference to  FIGS.  5 - 6   . The first RF connector port  360 - 1  on base station antenna  600  is coupled to the common port of a third diplexer  590 - 3 , and the second RF connector port  360 - 2  on base station antenna  600  is coupled to the common port of a fourth diplexer  590 - 4 . 
     A first frequency selective port on the third diplexer  590 - 3  is coupled to low-band radiating elements  242 - 6  and  242 - 7 , which are part of the first low-band array  240 - 1 , and which are mounted in the second base station antenna  600 . A second frequency selective port on the third diplexer  590 - 3  is coupled to the two mid-band radiating elements  252  that are part of the first mid-band array  550 - 1  that are mounted in the second base station antenna  600 . Similarly, a first frequency selective port on the fourth diplexer  590 - 4  is coupled to the remaining low-band radiating element  242 - 8  in the first low-band array, and a second frequency selective port on the fourth diplexer  590 - 4  is coupled to the two mid-band radiating elements  252  that are part of the second mid-band array  550 - 2  that are mounted in the second base station antenna  600 . 
     The first and third diplexers  590 - 1 ,  590 - 3  allow both a low-band RF signal and a mid-band RF signal to be simultaneously transmitted from the first base station antenna  500  to the second base station antenna  600  (or vice versa) through RF connection  510 - 1 . Similarly, the second and fourth diplexers  590 - 2 ,  590 - 4  allow both a low-band RF signal and a mid-band RF signal to be simultaneously transmitted from the first base station antenna  500  to the second base station antenna  600  (or vice versa) through a single RF connection  510 - 2 . Thus, the diplexers  590  allow the mid-band arrays  550  to span both antennas  500 ,  600  by sharing the RF connections  510  with the low-band arrays  240 . 
       FIG.  16 A  is a schematic front view of a base station antenna unit  400 ′ that is a modified version of the base station antenna unit  400  of  FIG.  15 A . The base station antenna unit  400 ′ is very similar to the base station antenna unit  400  of  FIG.  15 A , and hence the discussion below focuses on the differences between the two base station antenna units  400 ,  400 ′. 
     As can be seen by comparing  FIGS.  15 A and  16 A , the base station antenna unit  400 ′ differs from base station antenna unit  400  in that only two of the mid-band arrays  550  span the first and second base station antennas  500 ′,  600 ′, whereas all four mid-band arrays  550  span the first and second base station antennas  500 ,  600  in base station antenna unit  400 . Additionally, in the mid-band linear arrays  550 ′ that are included in base station antenna unit  400 ′, four mid-band radiating elements  252  are mounted in the second base station antenna  600 ′ for mid-band linear arrays  550 ′- 1  and  550 ′- 4  , as opposed to only two mid-band radiating elements  252  as is the case in base station antenna unit  400 . Each pair of mid-band radiating elements  252  in the second base station antenna  600 ′ are fed by a first of the RF connections  510  for first polarization signals and by a second of the of the RF connections  510  for second polarization signals. Thus, a total of eight RF connections are required between the first base station antenna  500 ′ and the second base station antenna  600 ′ for the mid-band linear arrays  550 . As with the embodiment of  FIGS.  15 A- 15 B , this is achieved by using diplexed connections  510 ′ that carry both low-band and mid-band RF signals. Finally, base station antenna unit  400 ′ includes a four column high-band array  350 ′ as opposed to the eight column high-band array  350  included in base station antenna unit  400  in order to make room for the additional mid-band radiating elements  252  that extend closer to the top of the base station antenna unit  400 ′ in the second base station antenna  600 ′. 
       FIG.  16 B  is a schematic block diagram illustrating the diplexed connections  510 ′ that may be used to pass low-band and mid-band RF signals (for one of the two polarizations) to the low-band radiating elements  242  and to the mid-band radiating elements  252  of linear arrays  240 - 1  and  550 ′- 1  that are mounted in the second base station antenna  600 ′ of the base station antenna unit  400 ′ of  FIG.  16 A . The circuit shown in  FIG.  16 B  would be replicated in base station antenna unit  400 ′ in order to support linear arrays  240 - 2  and  550 ′- 4  and these two circuits would then be replicated again to support the second polarization for each linear array  240 - 1 ,  240 - 2 ,  550 ′- 1 ,  550 ′- 4 . As can be seen, the circuit of  FIG.  16 B  is similar to the circuit of  FIG.  15 B , except that in the circuit of  FIG.  16 B  only one mid-band phase shifter  576  feeds the diplexers  590  since low-band linear array  240 - 1  and mid-band linear array  550 ′- 1  share the same two diplexers  590 - 1 ,  590 - 2  to pass two RF signals each to the second base station antenna  600 ′. 
     It should be noted that the 617-960 MHz low-band frequency band and the 1427- 2690  MHz mid-band frequency band are fairly widely separated in frequency, and hence relatively low cost, microstrip printed circuit board based diplexers may be used in some embodiments to implement the diplexers  590  while still providing acceptable isolation, return loss and insertion loss performance. 
       FIG.  17    is a schematic front view of a base station antenna unit  700  according to embodiments of the present invention that includes a first base station antenna  800  and a second base station antenna  900 . As shown in  FIG.  17   , the base station antenna unit  700  includes first and second arrays  240 - 1 ,  240 - 2  of low-band radiating elements  242 , first and second arrays  550 - 1 ,  550 - 2  of mid-band radiating elements  252 , an eight column array  350 - 1  of high-band radiating elements  352 , and a four column array  350 - 2  of high-band radiating elements  352 . The low-band linear arrays  240  and the mid-band linear arrays  550  each span both the first and second base station antennas  800 ,  900 . The low-band linear arrays  240 - 1 ,  240 - 2  and the mid-band linear arrays  550 - 1 ,  550 - 2  may be identical to the low-band linear arrays  240 - 1 ,  240 - 2  and the mid-band linear arrays  550 - 1 ,  550 - 4  that are included in base station antenna unit  400 , and hence further description thereof will be omitted. Similarly, the high-band linear array  350 - 1  may be identical to the high-band linear arrays  350  included in base station antenna unit  400 , and hence further description thereof will also be omitted. Thus, the primary difference between base station antenna unit  400  and base station antenna  700  is that two of the mid-band linear arrays  550 - 2 ,  550 - 3  included in base station antenna unit  400  are replaced in base station antenna unit  700  with the high-band linear array  350 - 2 . The high-band linear array  350 - 2  may, for example, be a Citizens Band Radio Service array that is configured to operate in the 3550-3700 MHz frequency band in some embodiments. 
     Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (i.e., “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.). 
     Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof. 
     Aspects and elements of all of the embodiments disclosed above can be combined in any way and/or combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.