Patent Publication Number: US-2023163486-A1

Title: Base station antennas having high directivity radiating elements with balanced feed networks

Description:
RELATED APPLICATION(S) 
     The present application claims priority to and the benefit of U.S. Provisional Application Serial No. 63/016,605, filed Apr. 28, 2020, and U.S. Provisional Application Serial No. 63/143,409, filed Jan. 29, 2021, the disclosures of which are hereby incorporated herein in their entireties. 
    
    
     BACKGROUND 
     The present invention generally relates to radio communications and, more particularly, to radiating elements for base station antennas used in cellular communications systems. 
     Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells” which are served by respective base stations. The base station may include one or more base station 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 base station is divided into “sectors.” In perhaps the most common configuration, a hexagonally shaped-cell is divided into three 120° sectors, and each sector is served by one or more base station antennas. Typically, the base station antennas are mounted on a tower or other raised structure, with the radiation patterns (also referred to as “antenna beams”) that are generated by the base station antennas directed outwardly. Base station antennas are often implemented as linear or planar phased arrays of radiating elements. 
     In order to accommodate the ever-increasing volume of cellular communications, cellular operators have added cellular service in a variety of new frequency bands. Cellular operators have applied a variety of approaches to support service in these new frequency bands, including deploying linear arrays of “wide-band” radiating elements that provide service in multiple frequency bands, and/or deploying multiband base station antennas that include multiple linear arrays (or planar arrays) of radiating elements that support service in different frequency bands. One very common multiband base station antenna design includes two linear arrays of “low-band” radiating elements that are used to provide service in some or all of the 694-960 MHz frequency band and four linear arrays of “high-band” radiating elements that are used to provide service in some or all of the 1427-2690 MHz frequency band. These linear arrays are mounted in side-by-side fashion. Unfortunately, implementing an antenna that includes all six of these linear arrays while maintaining the width of the antenna within acceptable limits and limiting undesirable interactions between the linear arrays may be difficult. 
     SUMMARY 
     Pursuant to embodiments of the present invention, radiating elements are provided that comprise a feed stalk and a first dipole arm, a second dipole arm, a third dipole arm and a fourth dipole arm that are each electrically coupled to the feed stalk. An outer segment of the first dipole arm and an outer segment of the second dipole arm are configured to together form a first radiating structure that radiates at a first polarization, and an outer segment of the third dipole arm and an outer segment of the fourth dipole arm are configured to together form a second radiating structure that radiates at the first polarization, and first and second inner portions of each of the first through fourth dipole arms are configured to together form a third radiating structure that radiates at the first polarization when a first RF signal is fed to the radiating element. 
     In some embodiments, the feed stalk may include a first RF transmission line, a second RF transmission line, a third RF transmission line, and a fourth RF transmission line. In some embodiments, at least a part of each of the first through RF transmission lines may comprise a respective stripline segment. 
     In some embodiments, a portion of the first dipole arm may extend adjacent to and in parallel to a portion of the second dipole arm to define a first slot, a portion of the second dipole arm may extend adjacent to and in parallel to a portion of the third dipole arm to define a second slot, a portion of the third dipole arm may extend adjacent to and in parallel to a portion of the fourth dipole arm to define a third slot, and a portion of the fourth dipole arm may extend adjacent to and in parallel to a portion of the first dipole arm to define a fourth slot. 
     In some embodiments, the first through fourth RF transmission lines, when excited, may be configured to apply voltage differentials across the respective first through fourth slots. 
     In some embodiments, the radiating element may be mounted on a reflector of a base station antenna, and the first and third dipole arms may be mounted to extend horizontally in front of the reflector and the second and fourth dipole arms may be mounted to extend vertically in front of the reflector when a longitudinal axis of the reflector extends in a vertical direction. The first and third slots may extend at an angle of about -45° with respect to the longitudinal axis of the reflector and the second and fourth slots may extend at an angle of about +45° respect to the longitudinal axis of the reflector. 
     In some embodiments, the first RF transmission line may extend directly behind the first slot, the second RF transmission line may extend directly behind the second slot, the third RF transmission line may extend directly behind the third slot, and the fourth RF transmission line may extend directly behind the fourth slot. 
     In some embodiments, a first conductor of the first RF transmission line may capacitively couple to the first dipole arm on a first side of the slot and the second conductor of the first RF transmission line may capacitively couple to a second side of the second dipole arm. 
     In some embodiments, each of the first through fourth RF transmission lines may partially cross behind a respective one of the first through fourth slots. 
     In some embodiments, each of the first through fourth RF transmission lines may partially cross behind a respective one of the first through fourth slots within a footprint of the feed stalk when the radiating element is viewed from the front. 
     Pursuant to further embodiments of the present invention, a radiating element is provided that comprises a first dipole arm, a second dipole arm, a third dipole arm and a fourth dipole arm arranged to form a cruciform shape, where first through fourth slots separate each of the first through fourth dipole arms from adjacent ones of the first through fourth dipole arms and a feed network that includes a first stripline segment, a second stripline segment, a third stripline segment, and a fourth stripline segment. Center conductors of the respective first through fourth stripline segments extend directly behind the respective first through fourth slots. 
     In some embodiments, the first through fourth dipole arms may be capacitively coupled to the center conductors of the respective first through fourth stripline segments, and the first through fourth dipole arms may also be capacitively coupled to ground. 
     In some embodiments, center conductors of the respective first through fourth stripline segments may capacitively couple to the respective first through fourth dipole arms along the inner half of the respective first through fourth slots. 
     In some embodiments, the radiating element may be mounted on a reflector of a base station antenna, and the first and third dipole arms may be mounted to extend horizontally in front of the reflector and the second and fourth dipole arms may be mounted to extend vertically in front of the reflector when a longitudinal axis of the reflector extends in a vertical direction. In such embodiments, the first and third slots may extend at an angle of about -45° with respect to the longitudinal axis of the reflector and the second and fourth slots may extend at an angle of about +45° respect to longitudinal axis of the reflector. 
     In some embodiments, the first through fourth dipole arms may each include first and second inner segments that together define the first through fourth slots, first and second outer segments that extend outwardly from distal ends of the respective first and second inner segments, and a third outer segment that connects distal ends of the first and second outer segments. In some embodiments, the first and second outer segments of each of the first through fourth dipole arms may extend in parallel to each other. In some embodiments, the third outer segments of each of the first through fourth dipole arms may extend at a 90° angle from the second outer segment. 
     In some embodiments, a base of each of the first through fourth dipole arms and a distal portion each of the first through fourth dipole arms may all lie in a common plane. 
     Pursuant to still further embodiments of the present invention, radiating elements are provided that comprise a first dipole arm, a second dipole arm, a third dipole arm and a fourth dipole arm and a feed stalk that includes a first RF transmission line that includes a first microstrip segment and a first stripline segment and a second RF transmission line that includes a second microstrip segment and a second stripline segment. 
     In some embodiments, these radiating element may further include a third RF transmission line that includes a third microstrip segment and a third stripline segment and a fourth RF transmission line that includes a fourth microstrip segment and a fourth stripline segment. 
     In some embodiments, the radiating element may be mounted to extend forwardly from a reflector of a base station antenna, and the first and second microstrip segments may be behind the reflector and the first and second stripline segments may be in front of the reflector. 
     In some embodiments, the radiating element may further include a first power divider having a first output that comprises the first microstrip segment and a second output that comprises the second microstrip segment. In some embodiments, the radiating element may also include a second power divider having a first output that comprises the third microstrip segment and a second output that comprises the fourth microstrip segment. 
     In some embodiments, a first coaxial cable may comprise the input to the first power divider. 
     In some embodiments, the feed stalk may include four sets of first and second parallel metal plates that form ground conductors of the first through fourth stripline segments. 
     In some embodiments, a first metal plate of each of the four sets of parallel metal plates may extend farther rearwardly than a second metal plate of each of the four sets of parallel metal plates. 
     In some embodiments, first through fourth metal pads may be provided at the front of the feed stalk that extend perpendicularly to the four sets of first and second parallel metal plates. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a side perspective view of a base station antenna according to embodiments of the present invention. 
         FIG.  1 B  is a schematic front view of the base station antenna of  FIG.  1 A  with the radome removed. 
         FIG.  2    is a perspective view of a low-band radiating element according to embodiments of the present invention that may be included in the base station antenna of  FIGS.  1 A- 1 B . 
         FIGS.  3 A and  3 B  are side perspective views of the feed stalk of the radiating element of  FIG.  2   . 
         FIGS.  3 C and  3 D  are side views of the feed stalk of the radiating element of  FIG.  2   . 
         FIG.  3 E  is a front view of the feed stalk of the radiating element of  FIG.  2   . 
         FIGS.  3 F and  3 G  are cut-away side views that show the feed lines of the feed stalk of the radiating element of  FIG.  2   . 
         FIGS.  4 A and  4 B  are a side view and a perspective view, respectively, of a rear portion of the feed stalk of the radiating element of  FIG.  2   . 
         FIG.  5 A  is a partially exploded perspective view of the radiating element of  FIG.  2    with three of the dipole arms removed. 
         FIG.  5 B  is a front perspective view of the radiating element of  FIG.  2   . 
         FIG.  5 C  is a front view of the four dipole arms of the radiating element of  FIG.  2   . 
         FIG.  5 D  is a schematic perspective view of an alternative implementation of one of the series capacitors implemented in the dipole arms of the radiating element of  FIG.  2   . 
         FIGS.  6 A and  6 B  are front views of the radiating element of  FIG.  2    that illustrates the direction of current flow on each dipole arm when the radiating element is excited to radiate RF energy having a +45° polarization and a -45° polarization, respectively. 
         FIG.  7 A  is a schematic exploded perspective view of a radiating element according to further embodiments of the present invention. 
         FIG.  7 B  is a perspective view of one of the four feed stalk members of the radiating element of  FIG.  7 A . 
         FIG.  7 C  is a front view of a stamped piece of sheet metal that may be bent to form one of the two feed stalk member configurations used in the radiating element of  FIG.  7 A . 
         FIG.  7 D  is a front view of another stamped piece of sheet metal that may be bent to form the other of the two feed stalk member configurations used in the radiating element of  FIG.  7 A . 
         FIG.  7 E  is an enlarged schematic view of the rear portion of the feed stalk of the radiating element of  FIG.  7 A  illustrating how coaxial feed cables may be coupled thereto. 
         FIG.  7 F  is a partial perspective view illustrating how a cruciform opening may be formed in the reflector to facilitate reworking solder joints after the radiating element of  FIG.  7 A  has been installed on a base station antenna. 
         FIG.  8    is a schematic perspective view of a modified version of the radiating element of  FIG.  7 A  that includes direct feeds and “split” feed stalks. 
         FIGS.  9 A- 9 D  are front views of the dipole arms of radiating elements according to four additional embodiments of the present invention. 
         FIG.  10 A  is a front view of the dipole arms of a radiating element according to another embodiment of the present invention. 
         FIG.  10 B  is a perspective view of one of the four feed stalks of a radiating element that includes the dipole arms shown in  FIG.  10 A . 
         FIGS.  11 A- 11 C  are front views of base station antennas that include two arrays of radiating elements according to embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Pursuant to embodiments of the present invention, dual-polarized, high directivity radiating elements are provided that include four dipole arms that are mounted on a feed stalk. The four dipole arms may be arranged in a cruciform shape and may be fed via four slots that are defined between adjacent dipole arms. These radiating elements may be inexpensive to manufacture, easy to assemble, and may be designed with cloaking features so that they are relatively invisible to other nearby radiating elements that operate in different frequency bands. In some embodiments, the radiating elements may be formed of stamped sheet metal and may be directly fed by pairs of feed cables without any need for a feed board printed circuit board. 
     In some embodiments, the radiating elements may include three separate radiating structures that each are configured to radiate at two different polarizations in response to appropriate RF feed signals. In some embodiments, an outer segment of the first dipole arm and an outer segment of the second dipole arm are configured to together form a first radiating structure that radiates at a first polarization, while an outer segment of the third dipole arm and an outer segment of the fourth dipole arm are configured to together form a second radiating structure that radiates at the first polarization. In addition, first inner portions of the first and third dipole arms and second inner portions of the second and fourth dipole arms are configured to together form a third radiating structure that radiates at the first polarization. The provision of three radiating structures may increase the directivity of the radiating element. 
     In some embodiments, the feed stalk may include first through fourth RF transmission lines that feed the respective first through fourth slots that are defined between the dipole arms. The first and third RF transmission lines may be coupled to a first coaxial feed cable through a first power divider, and the second and fourth RF transmission lines may be coupled to a second coaxial feed cable through a second power divider. The first and third RF transmission lines and the first power divider may be configured to split an RF signal injected from the first coaxial feed cable into two equal magnitude sub-components and to feed those sub-components to the first and third slots in-phase. Similarly, the second and fourth RF transmission lines and the second power divider may be configured to split an RF signal injected from the second coaxial feed cable into two equal magnitude sub-components and to feed those sub-components to the second and fourth slots in-phase. The dipole arms of the radiating element may be fed without the use of any balun. 
     In some embodiments, the feed stalk may include both stripline and microstrip RF transmission lines. For example, the feed stalk may include a first RF transmission line that includes a first microstrip segment and a first stripline segment, a second RF transmission line that includes a second microstrip segment and a second stripline segment, a third RF transmission line that includes a third microstrip segment and a third stripline segment and a fourth RF transmission line that includes a fourth microstrip segment and a fourth stripline segment. The stripline segments may extend forwardly from the reflector to a radiator unit of the radiating element. The microstrip segments may be positioned behind the reflector. The feed stalk may also include first and second power dividers. The power dividers may be implemented in the microstrip segments of the first through fourth RF transmission lines. In some embodiments, the first and third microstrip segments may comprise a first monolithic section of microstrip transmission line and the center conductor of the first coaxial feed cable may connect to the first monolithic section of microstrip transmission line to form the first power divider and to divide the first monolithic section of microstrip transmission line into the first and third microstrip segments. Similarly, the second and fourth microstrip segments may comprise a second monolithic section of microstrip transmission line and the center conductor of the second coaxial feed cable may connect to the second monolithic section of microstrip transmission line to form the second power divider and to divide the second monolithic section of microstrip transmission line into the second and fourth microstrip segments. 
     In some embodiments, the first through fourth stripline segments of the RF transmission lines may extend directly behind the respective first through fourth slots. The first through fourth stripline segments may capacitively couple to the respective first through fourth dipole arms. Center conductors of the respective first through fourth stripline transmission lines may capacitively couple to the respective first through fourth dipole arms along the inner half of the respective first through fourth slots (i.e., in the central portion of the radiating element). 
     In some embodiments, the dipole arms may be formed of stamped sheet metal, and plate capacitors may be implemented in the dipole arms. Additionally, one or more shunt inductor-capacitor (“L-C”) circuits may be coupled in series with the plate capacitors. The plate capacitor and the shunt L-C circuit may together for a band stop filter may allow RF signals in the operating frequency band of the radiating element to flow along the dipole arms while blocking RF signals in other frequency bands from flowing on the dipole arms. Such a design may be used to make the dipole arms substantially invisible to RF signals in the operating frequency band of other nearby radiating elements and/or may widen the impedance matching bandwidth of the radiating element. 
     Embodiments of the present invention will now be discussed in greater detail with reference to the accompanying figures. 
       FIGS.  1 A and  1 B  illustrate a base station antenna  10  according to certain embodiments of the present invention.  FIG.  1 A  is a schematic front perspective view of the base station antenna  10 , while  FIG.  1 B  is a front view of the antenna  10  with the radome thereof removed to illustrate the inner components of the antenna, 
     As shown in  FIG.  1 A , the base station antenna  10  is an elongated structure that extends along a longitudinal axis L. The base station antenna  10  may have a tubular shape with generally rectangular cross-section. The antenna  10  includes a radome  12  and a top end cap  14 , which may or may not be integral with the radome  12 . The antenna  10  also includes a bottom end cap  16  which includes a plurality of RF connectors  18  mounted therein that are used to pass RF signals to and from the arrays of radiating elements included in base station antenna  10 . The antenna  10  is typically mounted in a vertical configuration (i.e., the longitudinal axis L may be generally perpendicular to a plane defined by the horizon when the antenna  10  is mounted for normal operation). 
     As shown in  FIG.  1 B , the base station antenna  10  includes an antenna assembly  20  that may be slidably inserted into the radome  12 . The antenna assembly  20  includes a backplane  22  that includes a metallic surface that may serve as both a reflector  24  and as a ground plane for the radiating elements of the antenna  10 . Various mechanical and electronic components of the antenna (not shown) may be mounted behind the backplane  22  such as, for example, phase shifters, remote electronic tilt (“RET”) units, mechanical linkages, a controller, diplexers, and the like. 
     A plurality of dual-polarized low-band radiating elements  32  and a plurality of dual-polarized high-band radiating elements  42  are mounted to extend forwardly from the reflector  24 . As shown in  FIG.  1 B , the low-band radiating elements  32  are mounted in two vertical columns to form first and second linear arrays  30 - 1 ,  30 - 2  of low-band radiating elements  32 , and the high-band radiating elements  42  are mounted in four vertical columns to form firth through fourth linear arrays  40 - 1  through  40 - 4  of high-band radiating elements  42 . Note that herein when multiple like elements are provided, the elements may be identified by two-part reference numerals. The full reference numeral (e.g., linear array  40 - 2 ) may be used to refer to an individual element, while the first portion of the reference numeral (e.g., the linear arrays  40 ) may be used to refer to the elements collectively. Each linear array  30  of low-band radiating elements  32  may be positioned between two of the linear arrays  40  of high-band radiating elements  42 . Since dual-polarized radiating elements  32 ,  42  are used, each linear array  30 ,  40  may form a pair of antenna beams, namely a first antenna beam having a +45° polarization and a second antenna beam having a -45° polarization. 
     The low-band radiating elements  32  may be configured to transmit and receive RF signals in a first frequency band. In some embodiments, the first frequency band may comprise the 694-960 MHz frequency range or a portion thereof. The high-band radiating elements  42  may be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band may comprise the 1427-2690 MHz frequency range or a portion thereof. It will be appreciated that the number of linear arrays of radiating elements may be varied from what is shown in  FIG.  1 B , as may the number of radiating elements per linear array, the positions of the linear arrays, the operating frequency bands of the linear arrays, and/or the types of radiating elements included in the linear arrays. 
     As noted above, embodiments of the present invention provide low cost, high directivity radiating elements that may be used, for example, to implement each of the dual-polarized low-band radiating elements  32  shown in  FIG.  1 B .  FIG.  2    is a perspective view of a dual-polarized radiating element  100  that may be used to implement each of the dual-polarized low-band radiating elements  32  shown in  FIG.  1 B . 
     As shown in  FIG.  2   , the dual-polarized radiating element  100  includes a feed stalk  110  and a radiator unit  160 . The feed stalk includes a base  112  which may extend through and behind the reflector  24  of base station antenna  100  and a distal end  114  which is positioned forwardly of the reflector  24 . The feed stalk  110  may be mounted so that a longitudinal axis of the feed stalk  110  is perpendicular to the reflector  24 . The radiating element  100  is schematically depicted in  FIG.  2    as being in front of the reflector  24 , and it will be appreciated that in  FIG.  2    the radiating element  100  is not shown in its mounted position where the base  112  of the feed stalk  110  extends through an opening (not shown) in the reflector  24  so that the entire radiating element may be illustrated in the figure. 
     The radiator unit  160  includes first through fourth dipole arms  170 - 1  through 170-4 and a dielectric support  162 . Each dipole arm  170  may be formed of stamped sheet metal in some embodiments, although other implementations are possible (e.g., forming the dipole arms  170  on a printed circuit board). The dipole arms  170  are arranged to define a cruciform shape when the radiating element  100  is viewed from the front (which, in the orientation of  FIG.  2   , corresponds to being viewed from above). 
       FIGS.  3 A- 3 G  illustrate the design of the feed stalk  112  in greater detail. In particular,  FIGS.  3 A and  3 B  are side perspective views of the feed stalk  110 , and  FIGS.  3 C and  3 D  are side views of the feed stalk  110 .  FIG.  3 E  is a front view of the feed stalk  110 , and  FIGS.  3 F and  3 G  are cut-away side views that illustrate the feed lines  150 - 1 ,  150 - 2  that are disposed in the interior of the feed stalk  110 . 
     In the embodiment depicted in  FIGS.  3 A- 3 G , the feed stalk  110  includes a total of five metal pieces, namely three stalk members  120 - 1  through  120 - 3  and two feed lines  150 - 1 ,  150 - 2 . It will be appreciated, however, that more or fewer stalk members  120  and/or feed lines  150  may be included in other embodiments, as will be discussed in further detail below. In the depicted embodiment, the stalk members  120  may be die cast or machined parts. It will be appreciated, however, that stamped and bent sheet metal may be used to form the stalk members  120  in other embodiments. 
     Referring to  FIG.  3 A , the first stalk member  120 - 1  includes a first pair  122 - 1  of forwardly extending metal sheets  124 - 1 A,  124 - 1 B that are arranged perpendicular to each other. Sheets  124 - 1 A and  124 - 1 B are physically connected to each other, but it will be appreciated that two separate sheets could be used in other embodiments. A plate  128 - 1  having an opening  130 - 1  extends at a right angle from the rear portion of sheets  124 - 1 A,  124 - 1 B. The plate  128 - 1  may be used to mount the first stalk member  120 - 1  to the reflector  24  of base station antenna  100  using a bolt or rivet (not shown). The plate  128 - 1  may be connected to either or both of the sheets  124 - 1 A,  124 - 1 B. A plate  132 - 1  extends at a right angle from the forward portion of sheets  124 - 1 A,  124 - 1 B. The plate  132 - 1  may capacitively couple with a corresponding plate on a first of the dipole arms  170 - 1 , as will be discussed in greater detail below. The plate  132 - 1  may be connected to either or both of the sheets  124 - 1 A,  124 - 1 B. Openings  134 - 1 A,  134 - 1 B are provided near the forward end of sheets  124 - 1 A,  124 - 1 B, respectively. The openings  134 - 1 A,  134 - 1 B may receive respective rivets that are used to mount the feed lines  150 - 1 ,  150 - 2  within the interior of the feed stalk  110 . Finally, the outer central portion of each sheet  124 - 1 A,  124 - 1 B includes a respective recess  136 - 1 A,  136 - 1 B. The recesses  136 - 1 A,  136 - 1 B may be used ensure that the dielectric support  162  is mounted in the proper location on the feed stalk  110 . 
     Referring to  FIGS.  3 A- 3 C , the second stalk member  120 - 2  includes a second pair  122 - 2  of forwardly extending metal sheets  124 - 2 A,  124 - 2 B that are arranged perpendicular to each other. Sheets  124 - 2 A and  124 - 2 B are physically connected to each other, but need not be. A plate  128 - 2  having an opening  130 - 2  extends at a right angle from the rear portion of sheets  124 - 2 A,  124 - 2 B, and a plate  132 - 2  extends at a right angle from the forward portion of sheets  124 - 2 A,  124 - 2 B. The design and function of plates  128 - 2  and  132 - 2  may be the same as the design and function of plates  128 - 1  and  132 - 1 , and hence further description thereof will be omitted. Openings  134 - 2 A,  134 - 2 B and recesses  136 - 2 A,  136 - 2 B are provided in sheets  124 - 2 A,  124 - 2 B, respectively, which may be identical in design and function to the openings  134 - 1 A,  134 - 1 B and recesses  136 - 1 A,  136 - 1 B in sheets  124 - 1 A,  124 - 1 B, and hence further description thereof will be omitted. As best seen in  FIG.  3 C , sheet  124 - 2 A extends farther rearwardly than does sheet  124 - 2 A, so that sheet  124 - 2 A includes an extension  126 - 2  that extends rearwardly of plate  128 - 2 . As can best be seen in  FIGS.  3 C and  3 E , the extension  126 - 2  may also extend through an axis that bisects the feed stalk  110  when viewed from the front. 
     Referring to  FIGS.  3 A- 3 D , the third stalk member  120 - 3  includes a third pair  122 - 3  of forwardly extending metal sheets  124 - 3 A,  124 - 3 B and a fourth pair  122 - 4  of forwardly extending metal sheets  124 - 4 A,  124 - 4 B. Sheets  124 - 3 A,  124 - 3 B,  124 - 4 A and  124 - 4 B are all implemented as a single monolithic unit in the depicted embodiment, although embodiments of the present invention are not limited thereto. As shown in  FIG.  3 B , a plate  128 - 3  having an opening  130 - 3  extends at a right angle from the rear portion of sheets  124 - 3 A,  124 - 3 B, and a plate  132 - 3  extends at a right angle from the forward portion of sheets  124 - 3 A,  124 - 3 B. Similarly, a plate  128 - 4  having an opening (not visible in the figures) extends at a right angle from the rear portion of sheets  124 - 4 A,  124 - 4 B, and a plate  132 - 4  extends at a right angle from the forward portion of sheets  124 - 4 A,  124 - 4 B. The design and function of plates  128 - 3 ,  128 - 4 ,  132 - 3  and  132 - 4  may be the same as the design and function of plates  128 - 1  and  132 - 1 , and hence further description thereof will be omitted. Openings  134 - 3 A,  134 - 3 B;  134 - 4 A, 134-4B and recesses  136 - 3 A,  136 - 3 B;  136 - 4 A,  136 - 4 B are provided in sheets  124 - 3 A,  124 - 3 B;  124 - 4 A,  124 - 4 B, respectively, which may be identical in design and function to the openings  134 - 1 A,  134 - 1 B and recesses  136 - 1 A,  136 - 1 B in sheets  124 - 1 A,  124 - 1 B. 
     Sheets  124 - 3 A,  124 - 3 B,  124 - 4 A and  124 - 4 B each extend farther rearwardly than does sheet  124 - 2 A, so that sheets  124 - 3 A,  124 - 3 B extend rearwardly past plate  128 - 3 , and so that sheets  124 - 4 A,  124 - 4 B extend rearwardly past plate  128 - 4 . As best seen in  FIG.  3 D , sheets  124 - 3 A and  124 - 4 B each extend farther rearwardly than do sheets  124 - 3 B and  124 - 4 A, respectively, so that sheet  124 - 3 A includes an extension  126 - 3  that extends rearwardly of plate  128 - 3  and sheet  124 - 4 B includes an extension  126 - 4  that extends rearwardly of plate  128 - 4 . Extensions  126 - 3  and  126 - 4  are joined together through a connecting section  127  that is behind a channel  140 - 2  (which is discussed in further detail below). A first opening  129 - 1  is provided through connecting section  127 , and a dielectric gasket that includes an opening is positioned in the first opening  129 - 1 . Similarly, a second opening  129 - 2  is provided through extension  126 - 1 , and a dielectric gasket that includes an opening is positioned in the second opening  129 - 2 . 
     Each of the four pairs  122 - 1  through  122 - 4  of sheets  124  are positioned in one of four quadrants of a square when the feed stalk  110  is viewed from the front, as is best shown in  FIG.  3 E . Each pair  122  faces two other of the pairs  122  and is positioned diagonally with respect to the third pair  122 . The sheets  124  are spaced apart from one another, with each sheet  124  of a pair  122  being positioned parallel to sheets  124  of the two other facing pairs  122 . In particular, sheets  124 - 1 A and  124 - 4 B extend in parallel, sheets  124 - 1 B and  124 - 2 A extend in parallel, sheets  124 - 2 B and  124 - 3 A extend in parallel, and sheets  124 - 3 B and  124 - 4 A extend in parallel. 
     First and second channels  140 - 1 ,  140 - 2  bisect the feed stalk  110 . Channel 140-1 is perpendicular to channel  140 - 2 . The channel slot  140 - 1  is defined by parallel sheets 124-1B and  124 - 2 A and  124 - 3 B and  124 - 4 A, and the second channel  140 - 2  is defined by parallel sheets  124 - 1 A and  124 - 4 B and  124 - 2 B and  124 - 3 A. In the depicted embodiment, the channels  140 - 1 ,  140 - 2  extend the full length of the feed stalk  110  (although the lateral extensions  126  do cross the channels  140 ). 
     The feed lines  150 - 1 ,  150 - 2  are best illustrated in  FIGS.  3 F and  3 G . Each feed line  150  may comprise an elongated piece of stamped sheet metal that has a general U-shape. The “arms”  152 - 1 A,  152 - 1 B,  152 - 2 A,  152 - 2 B of each feed line  150  extend in the longitudinal direction of the feed stalk  110  (i.e., from front-to-rear). The forward end of each arm 152 includes a respective widened plate-like section  154  that includes a respective opening 156 therethrough. The plates  154  act as a mechanical support structure for a rivet or other fastener that may be used to control the gaps between the feed lines  150  and the sheets  124  that form the outer walls of the stripline structure with the feedlines sandwiched in between. The forward end of each arm  152  further includes a tab  158  that extends at a right angle from its associated plate  154 . The tabs  158  may be formed by bending the stamped sheet metal used to form the feed lines  150 . Each arm  152  includes a meandered section  160 . The meandered sections  160  may help ensure that the feed lines  150  have a proper input for impedance matching purposes without increasing the length of the feed stalk  110 . The rear end of each arm  152  connects to a base section  162  of the respective feed lines  150 . Each base section  162  may be a short generally C-shaped piece of metal that joins the two arms  152  of a respective feed line  150 . Each feed line  150  may comprise a monolithic piece of metal. Openings  163 - 1 ,  163 - 2  are provided in the base sections  162  of feed lines  150 - 1 ,  150 - 2 , respectively. As discussed below, center conductors of respective coaxial feed cables may be inserted through the openings  163 - 1 ,  163 - 2  and soldered in place to pass RF signals between the feed lines  150 - 1 ,  150 - 2  and other elements of a base station antenna. 
     Still referring to  FIGS.  3 F and  3 G , feed line  150 - 2  is longer than feed line  150 - 1 . Feed line  150 - 1  is positioned within the interior of feed line  150 - 2  and at a right angle to feed line  150 - 2 . As is shown best in  FIG.  3 E , feed line  150 - 1  is positioned in channel  140 - 1  and feed line  150 - 2  is positioned in channel  140 - 2 . 
     Referring to  FIGS.  4 A and  4 B  the plates  128 - 1  through  128 - 4  may be used to mount the feed stalk  110  so that it extends forwardly from a reflector  24  of base station antenna  10 . As best shown in  FIGS.  3 A and  3 E- 3 G , the metal sheets  124  and the arms  152  of feed lines  150  may form four stripline segments  164 - 1  through  164 - 4  that extend forwardly from the reflector  24  to the front end  114  of the feed stalk  110 . As is known to those of skill in the art, a stripline segment refers to a transmission line segment that includes a conductive trace that has a grounded metal sheets on opposed sides thereof, with a dielectric material interposed between the conductive trace and the respective grounded metal sheets. As shown in  FIG.  3 E , arm  152 - 1 B of feed line  150 - 1  extends between parallel sheets  124 - 1 B and  124 - 2 A to form a first stripline segment  164 - 1 , arm  152 - 2 B of feed line  150 - 2  extends between parallel sheets  124 - 2 B and  124 - 3 A to form a second stripline segment  164 - 2 , arm  152 - 1 A of feed line  150 - 1  extends between parallel sheets  124 - 3 B and  124 - 4 A to form a third stripline segment  164 - 3 , and arm  152 - 2 A of feed line  150 - 2  extends between parallel sheets  124 - 4 B and  124 - 1 A to form a fourth stripline segment  164 - 4 . 
     Dielectric rivets and spacers (not shown) are inserted through openings  134  in the metal sheets  124  and through the openings  156  in the feed lines  150  to assemble the feed stalk 110 and to maintain the arms  152  of the feed lines  150 - 1 ,  150 - 2  at the proper distance from the sheets  124  to maintain the proper impedance for the stripline segments  164 . Each stripline segment  164  is a so-called “air” stripline as the dielectric material that separates the feed lines from the grounded metal sheets is primarily air. 
     Referring again to  FIGS.  4 A- 4 B , first and second coaxial feed cables  168 - 1 ,  168 - 2  may be used to pass RF signals to and from the radiating element  100 . As shown in  FIG.  4 A , the outer conductor of the first coaxial feed cable  168 - 1  may be soldered or otherwise electrically connected to the laterally extending connecting section  127  that joins sheet  124 - 3 A to sheet  124 - 4 B. The center conductor of the first coaxial feed cable  168 - 1  may extend through the opening 129-1 in the laterally extending connecting section  127  and through the opening  163 - 1  in the base  162  of feed line  150 - 1 . The center conductor of the first coaxial feed cable  168 - 1  may be soldered to the base  162  of feed line  150 - 1 . The outer conductor of the second coaxial feed cable 168-2 may be soldered or otherwise electrically connected to the extension  126 - 1  of sheet  124 - 3 B. The center conductor of the second coaxial feed cable  168 - 2  may extend through the opening  129 - 2  in the extension  126 - 1  and through the opening  163 - 2  in the base  162  of feed line 150-2. The center conductor of the second coaxial feed cable  168 - 2  may be soldered to the base 162 of feed line  150 - 2 . The second coaxial feed cable  168 - 2  includes a 90° bend so that it runs parallel to the first coaxial feed cable  168 - 1 . The first and second coaxial feed cables  168 - 1 , 168-2 connect to the feed stalk  110  behind the reflector  24 . 
     As described above, the metal sheets  124  and the forward sections of the feed lines  150  form four stripline segments  164 - 1  through  164 - 4 . Similarly, the metal sheets  124  and the rearmost sections of the feed lines  150  form first through fourth microstrip segments 166-1 through  166 - 4  that are connected to the respective first through fourth stripline segments 164-1 through  164 - 4 . 
     Each microstrip segment  166  includes a conductive trace that is separated from a ground plane by an air dielectric. The conductive trace of the first microstrip segment  166 - 1  comprises the portion of the base section  162  of feed line  150 - 1  that extends from opening  163 - 1  to plate  128 - 1 , and the ground plane of the first microstrip segment  166 - 1  comprises the extension  126 - 2  of sheet  124 - 2 A. The conductive trace of the second microstrip segment  166 - 2  comprises the portion of the base section  162  of feed line  150 - 2  that extends from opening  163 - 2  to plate  128 - 2 , and the ground plane of the second microstrip segment  166 - 2  comprises the extension  126 - 3  of sheet  124 - 3 A. The conductive trace of the third microstrip segment  166 - 3  comprises the portion of the base section  162  of feed line  150 - 1  that extends from opening  163 - 1  to plate  128 - 3 , and the ground plane of the third microstrip segment  166 - 3  comprises the extension  126 - 1  of sheet  124 - 3 B. The conductive trace of the fourth microstrip segment  166 - 4  comprises the portion of the base section  162  of feed line  150 - 2  that extends from opening  163 - 2  to plate  128 - 4 , and the ground plane of the fourth microstrip segment  166 - 4  comprises the extension  126 - 4  of sheet  124 - 4 B. The first through fourth microstrip segments  166 - 1  through  166 - 4  are positioned behind the reflector  24 . By forming the portions of the RF transmission lines that are behind the reflector  24  as microstrip segments, it may be easier to physically and electrically connect the coaxial feed cables  168 - 1 ,  168 - 2  to the feed stalk  110 . 
     The connection of the center conductor of the first coaxial cable  168 - 1  to feed line  150 - 1  and the outer conductor of the first coaxial cable  168 - 1  to sheet  124 - 3 B forms a first power divider  169 - 1 . An RF signal input on the first coaxial cable  168 - 1  splits as it passes to feed line  150 - 1  and travels on the two arms  152  thereof. The connection of the center conductor of the second coaxial cable  168 - 2  to the feed line  150 - 2  and the outer conductor of the second coaxial cable  168 - 2  to sheets  124 - 3 A and  124 - 4 B forms a second power divider  169 - 2 . An RF signal input on the second coaxial cable  168 - 2  splits as it passes to feed line  150 - 2  and travels on the two arms  152  thereof. Typically, the first and second power dividers  169 - 1 ,  169 - 2  are designed to equally split RF signals input thereto. It will also be appreciated that the first and second power dividers  169 - 1 ,  169 - 2  will operate as power combiners for RF signals received by radiating element  100 . 
       FIGS.  5 A- 5 C  illustrate the radiator unit  160  of radiating element  100  in greater detail. In particular,  FIGS.  5 A and  5 B  are a partially exploded perspective view and a front perspective view of the radiating element  100 . Only one of the dipole arms is shown in the view of  FIG.  5 A .  FIG.  5 C  is a front view of the four dipole arms  170 - 1  through  170 - 4  of the radiating element  100 . 
     Each dipole arm  170  may have an identical design. As shown in  FIGS.  5 A- 5 C , each dipole arm  170  may be shaped generally in the form of an irregular pentagon, although other shapes may be used. In the depicted embodiment, each dipole arm  170  is shaped like a rectangle with an isosceles triangle attached to one side with the overlapping segments of the rectangle and the triangle omitted. Consequently, each dipole arm  170  includes five generally linear segments, namely first and second inner segments  172 ,  174  and first through third outer segments  176 ,  178 ,  180 . 
     Focusing on dipole arm  170 - 1 , the first inner segment  172  extends at an angle of +45° while the second inner segment  174  extends at an angle of -45°. The first and second inner segments  172 ,  174  each include a widened base and a narrowed distal end. The widened bases of the first and second inner segments  172 ,  174  together form a rectangular plate  175 . The distal end of the first inner segment  172  connects to a proximate end of the first outer segment  176 , and the distal end of the second inner segment  174  connects to a proximate end of the second outer segment  178 . The third outer segment  180  connects the distal end of the first outer segment  176  to the distal end of the second outer segment  178 . The first, second and third outer segments  176    174 ,  178  connect to each other at right angles to form three sides of the “rectangle” portion of the irregular pentagon shape formed by each dipole arm  170 , while the first and second inner segments  172 ,  174  form the two sides of the isosceles triangle that extends from the rectangle. Together, the four dipole arms  170  define a cruciform shape when viewed from the front. 
     As shown best in  FIG.  5 A , each dipole arm  170  may be formed of first and second pieces of stamped sheet metal  182 ,  184  that are bent into the shape shown in  FIGS.  5 A and  5 B . The first piece of stamped sheet metal  182  may comprise the first and second inner segments  172 ,  174  and a portion (here, about half) of the first and second outer segments  176 ,  178 . The second piece of stamped sheet metal  184  may comprise the third outer segment  180  and the remainder of the first and second outer segments  176 ,  178 . In an example embodiment, the dipole arms  170  may be formed from sheet metal that is, for example, 0.5-1.2 mm thick (e.g., 0.8 mm thick). The sheet metal may comprise, for example, aluminum or copper. 
     As shown best in  FIG.  5 C , slots  192  are formed between adjacent dipole arms 170. In particular, a first slot  192 - 1  is formed between the second inner segment  174  of dipole arm  170 - 1  and the first inner segment  172  of dipole arm  170 - 2 , a second slot  192 - 2  is formed between the second inner segment  174  of dipole arm  170 - 2  and the first inner segment  172  of dipole arm  170 - 3 , a third slot  192 - 3  is formed between the second inner segment  174  of dipole arm  170 - 3  and the first inner segment  172  of dipole arm  170 - 4 , and a fourth slot  192 - 4  is formed between the second inner segment  174  of dipole arm  170 - 4  and the first inner segment  172  of dipole arm  170 - 1 . 
     As shown in  FIG.  5 B , the two ends of the first piece of stamped sheet metal  182  are widened to form plates  186 , and the plates  186  are bent forwardly at an angle of 90° with respect to the remainder of the first piece of stamped sheet metal  182 . Likewise, the two ends of the second piece of stamped sheet metal  184  are widened to form plates  188 , and the plates  188  are bent forwardly at an angle of 90° with respect to the remainder of the second piece of stamped sheet metal  184 . Each plate  186  is positioned parallel to a corresponding plate  188  and spaced apart therefrom by a small gap so that each pair of plates  186 ,  188  forms a capacitor  190 . 
     The third outer segment  180  of each dipole arm  170  further includes a pair of meandered trace segments  193 , which are each implemented as U-shaped trace segment. The arms  194  of each U-shaped trace segment  193  may be narrower than other portions of the dipole arm  170  so that inductors are formed along the current path on each dipole arm  170 . Capacitive coupling may occur between the arms  194 , and hence each U-shaped trace segment  193  may form a shunt L-C circuit with the inductance value L determined by the length and width (and thickness) of the narrowed arms  194  and the capacitance value C determined by the gap between the arms  194  and the length and thickness of the arms  194 . The shunt L-C circuit formed by each U-shaped trace segment  193  is disposed in series with at least one of the capacitors  190 . Additional shunt L-C circuits  193  may be formed in the first inner segments  172  and the second inner segments  174  of each dipole arm  170 . 
     As explained in an article entitled Suppression of Cross-Band Scattering in Multiband Antenna Arrays by Hai-Han Sun, Can Ding, He Zhu and Bevan Jones, IEEE Transactions on Antennas and Propagation, Vol. 67, No. 4, April 2019, at 2379-2389, the above described arrangement of a shunt L-C circuit in series with a capacitor can be used to form a band stop filter along the dipole arm  170 . The band stop filter may be tuned to allow RF signals in the operating frequency range of radiating element  100  to pass along the dipole arms  170 , while blocking RF signals in other frequency bands, specifically including frequencies within the operating frequency range of radiating elements that operate in other frequency bands that are positioned nearby radiating element  100 . 
     While  FIGS.  5 A- 5 C  illustrate the plates  186 ,  188  that form the capacitors  190  as extending forwardly from radiating element  100 , embodiments of the present invention are not limited thereto. For example, as shown in  FIG.  5 D , in another embodiment plates  186 ′ may be formed at the distal ends of the first piece of stamped sheet metal  182  and plates  188 ′ may be formed at the distal ends of the second piece of stamped sheet metal  184 . One of the first or second pieces of stamped sheet metal  182 ,  184  may include a pair of 90° bends that allow the two plates  186 ′,  188 ′ to be arranged in parallel and spaced-apart arrangement to each other, with each plate  186 ′,  188 ′ extending parallel to a plane defined by the remainder of the dipole arm  170  to form a capacitor  190 ′. The design shown in  FIG.  5 D  may be advantageous because it may reduce the extent to which the radiating element  100  extends forwardly from the reflector. 
     The radiating element  100  may include capacitive connections between the feed stalk  110  and the dipole arms  170 . This may be advantageous as it may avoid the need for soldered connections, which may be labor intensive and which can increase manufacturing time and cost, and because the capacitive connections may avoid the passive intermodulation distortion issue that can arise with poor quality soldered connections (or soldered connections that are later subjected to stress). The ground connections between the feed stalk  110  and the dipole arms  170  may be achieved by capacitive connections that are formed between the plates  132  at the forward ends of the sheets  124  of feed stalk  110  (each of which are at ground potential) and the rectangular plates  175  that are provided at the base of each dipole arm  170 . A dielectric pad  194  may be interposed between the plates  132  and the plates  175  to act as the dielectric for these capacitive connections. 
     Capacitive connections may also be provided between the feed lines  150 - 1 ,  150 - 2  and the dipole arms  170 . In particular, the tabs  158  on each feed line  150  extend from the middle of a respective one of the channels  140 - 1 ,  140 - 2  to one side of the channel  140 , as is best shown in  FIGS.  3 A- 3 B . The dielectric pad  194  covers each tab  158  and separates it from the respective dipole arms  170 . When an RF signal is applied to the feed lines  150 , the tabs  158  generate a voltage differential across each slot  192  between adjacent dipole arms  170 , thereby exciting the dipole arms  170  to radiate. 
     As shown in  FIG.  5 A , the dielectric support  162  may comprise a unitary plastic support that includes four dipole arm supports  164  and a plurality of buttresses  166  that provide additional support to the dipole arm supports  164 . The dielectric support  162  may be mounted on the feed stalk  110 . The dielectric support  162  may be formed, for example, via injection molding. 
       FIG.  6 A  is a schematic front view of the dipole arms  170  of radiating element 100 that illustrates the direction of current flow on the dipole arms  170  in response to an RF signal being input to radiating element  100  from coaxial feed cable  168 - 1 . As shown in  FIG.  6 A , when radiating element  100  is excited by an RF signal provided by coaxial feed cable  168 - 1 , currents flow upwardly on the third outer segment  180  of dipole arm  170 - 1 , and flow to the right on the third outer segment  180  of dipole arm  170 - 2 . The third outer segments  180  of dipoles arms  170 - 1  and  170 - 2  together act as a first radiating structure, and applying superposition principles it can be seen that the currents flowing on these two outer segments  180  together emit radiation having a +45° polarization. Additionally, when radiating element  100  is excited by the RF signal provided by coaxial feed cable  168 - 1 , currents flow to upwardly on the third outer segment  180  of dipole arm  170 - 3 , and flow to the right on the third outer segment  180  of dipole arm  170 - 4 . The third outer segments  180  of dipoles arms  170 - 3  and  170 - 4  together act as a second radiating structure, and applying superposition principles it can be seen that the currents flowing on these two outer segments  180  together also emit radiation having a +45° polarization. As is further shown in  FIG.  6 A , currents flow from the bottom/left to the top/right on both the first internal segments  172  of dipole arms  170 - 1  and  170 - 3  and on the second internal segments 174 of dipole arms  170 - 2  and  170 - 4 . These internal segments  172 ,  174  form a third radiating structure that also emits radiation having a +45° polarization. 
       FIG.  6 B  is a schematic front view of the dipole arms  170  of radiating element 100 that illustrates the direction of current flow on the dipole arms  170  in response to an RF signal being input to radiating element  100  from coaxial feed cable  168 - 2 . As shown in  FIG.  6 B , when radiating element  100  is excited by an RF signal provided by coaxial feed cable  168 - 2 , currents flow upwardly on the third outer segment  180  of dipole arm  170 - 1 , and flow to the left on the third outer segment  180  of dipole arm  170 - 2 . The third outer segments  180  of dipoles arms  170 - 1  and  170 - 2  together act as a first radiating structure, and applying superposition principles it can be seen that the currents flowing on these two outer segments  180  together emit radiation having a -45° polarization. Additionally, when radiating element  100  is excited by the RF signal provided by coaxial feed cable  168 - 1 , currents flow to upwardly on the third outer segment  180  of dipole arm  170 - 3 , and flow to the left on the third outer segment  180  of dipole arm  170 - 4 . The third outer segments  180  of dipoles arms  170 - 3  and  170 - 4  together act as a second radiating structure, and applying superposition principles it can be seen that the currents flowing on these two outer segments  180  together also emit radiation having a -45° polarization. As is further shown in  FIG.  6 B , currents flow from the bottom/right to the top/left on both the first internal segments  172  of dipole arms  170 - 2  and  170 - 4  and on the second internal segments 174 of dipole arms  170 - 1  and  170 - 3 . These internal segments  172 ,  174  form a third radiating structure that also emits radiation having a -45° polarization. Since the radiating element  100  has three separate radiating structures for each polarization, it may exhibit higher directivity as compared to conventional radiating elements. 
       FIGS.  7 A- 7 F  illustrate a dual-polarized radiating element  200  according to further embodiments of the present invention. In particular,  FIG.  7 A  is a schematic exploded perspective view of the radiating element  200 .  FIG.  7 B  is a perspective view of one of the four feed stalk members of the radiating element  200 , and  FIGS.  7 C and  7 D  are front views of stamped pieces of sheet metal that may be bent to form the two respective feed stalk member configurations used in the radiating element  200 .  FIG.  7 E  is an enlarged schematic view of the rear portion of the feed stalk of radiating element  200  illustrating how coaxial feed cables may be coupled thereto. Finally,  FIG.  7 F  is a partial perspective view illustrating how a cruciform opening may be formed in the reflector of a base station antenna that includes the radiating element  200  in order to facilitate reworking solder joints after the radiating element  200  has been installed on the reflector. The dual-polarized radiating element  200  may be used, for example, in place of the dual-polarized low-band radiating elements  32  shown in  FIG.  1 B . 
     As shown in  FIG.  7 A , the dual-polarized radiating element  200  includes a feed stalk  210  and a radiator unit  260 . The feed stalk includes a base which may be mounted to extend forwardly from the reflector  24  of base station antenna  100 , and a distal end which is positioned forwardly of the base. The radiator unit  260  is mounted on the distal (forward) end of the feed stalk  210 . The feed stalk  210  may be mounted so that a longitudinal axis thereof is perpendicular to the reflector  24 . 
     The radiator unit  260  includes first through fourth dipole arms  270 - 1  through  270 - 4  and a dielectric spacer  262 . Each dipole arm  270  may be formed of stamped sheet metal in some embodiments, although other implementations are possible (e.g., forming the dipole arms  270  on one or more printed circuit boards). The dipole arms  270  are arranged to define a cruciform shape when the radiating element  200  is viewed from the front (which, in the orientation of  FIG.  7 A , corresponds to being viewed from above). 
       FIGS.  7 A- 7 C  show the design of the feed stalk  210 . The feed stalk  210  includes a total of four metal pieces  214 - 1  through  214 - 4  that form four stalk members  220 - 1  through  220 - 4  and four feed lines  250 - 1  through  250 - 4 . In the depicted embodiment, the four metal pieces  214  may be formed by stamping and bending a piece of sheet metal.  FIG.  7 C  illustrates a first stamped piece of sheet metal  216  that may be used to form the first metal piece  214 - 1  (and an identical stamped piece of sheet metal  216  may be used to form the third metal piece  214 - 3 ).  FIG.  7 D  illustrates a second stamped piece of sheet metal  218  that may be used to form the second a metal piece  214 - 2  (and an identical stamped piece of sheet metal  218  may be used to form the fourth metal piece  214 - 4 ). It will be appreciated, however, that more or fewer stalk members  220  and/or feed lines  250  may be included in other embodiments. 
     Referring to  FIGS.  7 B and  7 C , the first stamped piece of sheet metal  216  may be used to form the first stalk member  220 - 1  and the first and third feed lines  250 - 1 ,  250 - 3 . The first stalk member  220 - 1  comprises a first pair of forwardly extending metal sheets  224 - 1 A,  224 - 1 B that are arranged perpendicular to each other. Sheets  224 - 1 A and  224 - 1 B are physically connected to each other, but it will be appreciated that two separate sheets could be used in other embodiments (see  FIG.  8    and discussion thereof below). A rear plate  228 - 1  having an opening 230-1 extends at a right angle from the rear portion of sheet  224 - 1 B. The plate  228 - 1  may be used to mount the first stalk member  220 - 1  to the reflector  24  of base station antenna  100  using a bolt or rivet (not shown). While the rear plate  228 - 1  is connected to sheet  224 - 1 B in the depicted embodiment, it will be appreciated that it could alternatively or additionally be connected to sheet  224 - 1 A in other embodiments. An opening  234 - 1 A is provided near the rear end of sheet  224 - 1 A, and an opening  234 - 1 B is provided near the rear end of sheet  224 - 1 B. The openings  234 - 1 A,  234 - 1 B may receive a coaxial cable (or a portion thereof) that connects to one of the feed lines  250 , as will be explained below. A first thin arm  226 - 1 A extends perpendicularly from the forward (distal) end of sheet  224 - 1 A, and a second thin arm  226 - 1 B extends perpendicularly from the forward (distal) end of sheet  224 - 1 B. The first and second arms  226 - 1 A,  226 - 1 B may extend perpendicularly to each other, as shown in  FIG.  7 B . A forward plate 232-1A extends from a distal end of the first arm  226 - 1 A, and a forward plate  232 - 1 B extends from a distal end of the second arm  226 - 1 B. The plates  232 - 1 A,  232 - 1 B may define angles of 45° with respect to the arms  226 - 1 A,  226 - 1 B from which they extend. Small tabs  233 - 1 A,  233 - 1 B may connect the plates  232 - 1 A,  232 - 1 B to the respective arms  226 - 1 A,  226 - 1 B. Each plate 232-1A,  232 - 1 B may be bent 90° with respect to the arm  226 - 1 A,  226 - 1 B from which it extends. The plates  232 - 1 A,  232 - 1 B may capacitively couple with corresponding plates on a first of the dipole arms  270 - 1 , as will be discussed in greater detail below. 
     The first feed line  250 - 1  is connected to the forward portion of metal sheet  224 - 1 B by a tab  252 - 1 . The first feed line  250 - 1  comprises a rectangular strip of metal that extends forwardly from a position that is slightly forward of the front surface of the reflector  24 . Starting with the first stamped piece of sheet metal  216  shown in  FIG.  7 C , the first feed line  250 - 1  is bent through an angle of 180° to extend parallel to metal sheet  224 - 1 B. The rear portion of the first feed line  250 - 1  includes an opening  263 - 1  that receives a center conductor of a first coaxial feed cable. A tab  236 - 1  extends outwardly from a central portion of the first feed line  250 - 1 . The tab 236-1 is part of the impedance matching circuit of the radiating element  200 . 
     The third feed line  250 - 3  may be essentially identical to the first feed line  250 - 1 . The third feed line  250 - 3  is connected to the forward portion of metal sheet  224 - 1 A by a tab  252 - 3 . The third feed line  250 - 3  comprises a rectangular strip of metal that extends forwardly from a position that is slightly forward of the front surface of the reflector  24 , and extends parallel to metal sheet  224 - 1 A. The rear portion of the third feed line  250 - 3  includes an opening  263 - 3  that receives a center conductor of a third coaxial feed cable. A tab  236 - 3  extends outwardly from a central portion of the third feed line  250 - 3 . 
     Another piece of metal that is shaped identically to the first stamped piece of sheet metal  216  shown in  FIG.  7 C  may be used to form the third stalk member  220 - 3  and the second and fourth feed lines  250 - 2 ,  250 - 4 . As the third stalk member  220 - 3  and the second and fourth feed lines  250 - 2 ,  250 - 4  may be identical to the above discussed first stalk member  220 - 1  and the first and third feed lines  250 - 1 ,  250 - 3 , further description thereof will be omitted. 
     Referring to  FIGS.  7 A and  7 D , the second stamped piece of sheet metal 218 may be used to form the second stalk member  220 - 2 . The second stalk member  220 - 2  includes a second pair of forwardly extending metal sheets  224 - 2 A,  224 - 2 B that are arranged perpendicular to each other. Sheets  224 - 2 A and  224 - 2 B are physically connected to each other, but it will be appreciated that two separate sheets could be used in other embodiments). A rear plate  228 - 2  having an opening  230 - 2  extends at a right angle from the rear portion of sheet  224 - 2 B. The rear plate  228 - 2  may be used to mount the second stalk member  220 - 2  to the reflector  24 . While the rear plate  228 - 2  is connected to sheet  224 - 2 B in the depicted embodiment, it will be appreciated that it could alternatively or additionally be connected to sheet  224 - 1 A in other embodiments. An opening  234 - 2 A is provided near the rear end of sheet  224 - 2 A, and an opening  234 - 2 B is provided near the rear end of sheet  224 - 2 B. The openings  234 - 2 A,  234 - 2 B may receive a coaxial cable (or a portion thereof) that connects to one of the feed lines  250 , as will be explained below. A first thin arm  226 - 2 A extends perpendicularly from the forward (distal) end of sheet  224 - 2 A, and a second thin arm  226 - 2 B extends perpendicularly from the forward (distal) end of sheet  224 - 2 B. The first and second arms  226 - 2 A,  226 - 2 B may extend perpendicularly to each other. A forward plate  232 - 2 A extends from a distal end of the first arm  226 - 2 A, and a forward plate  232 - 2 B extends from a distal end of the second arm  226 - 2 B. The plates  232 - 2 A, 232-2B may define angles of 45° with respect to the arms  226 - 2 A,  226 - 2 B from which they extend. Small tabs  233 - 2 A,  233 - 2 B may connect the plates  232 - 2 A,  232 - 2 B to the respective arms  226 - 2 A,  226 - 2 B. Each plate  232 - 2 A,  232 - 2 B may be bent 90° with respect to the arm  226 - 2 A,  226 - 2 B from which it extends. The plates  232 - 2 A,  232 - 2 B may capacitively couple with corresponding plates on a first of the dipole arms  270 - 2 . 
     Another piece of metal that is shaped identically to the stamped piece of sheet metal  218  shown in  FIG.  7 D  may be used to form the fourth stalk member  220 - 4 . As the fourth stalk member  220 - 4  may be identical to the above discussed second stalk member  220 - 2 , further description thereof will be omitted. 
     As shown in  FIG.  7 A , each of the four feed stalk members  220 - 1  through  220 - 4  is positioned in a respective one of the four quadrants of a square when the feed stalk  210  is viewed from the front. Each feed stalk members  220  faces two other feed stalk members  220  and is positioned diagonally with respect to the remaining feed stalk member  220 . The feed stalk members  220  are spaced apart from one another, with each feed stalk member  220  being positioned parallel to a sheet  224  of a facing feed stalk member  220 . 
     First and second channels  240 - 1 ,  240 - 2  bisect the feed stalk  210 . Channel  240 - 1  is perpendicular to channel  240 - 2 . The first channel  240 - 1  is defined by parallel sheets  224 - 1 B and  224 - 2 A and  224 - 3 B and  224 - 4 A, and the second channel  240 - 2  is defined by parallel sheets  224 - 1 A and  224 - 4 B and  224 - 2 B and  224 - 3 A. The channels  240 - 1 ,  240 - 2  extend the full length of the feed stalk  210 . 
     The metal sheets  224  and the feed lines  250  may form four forwardly extending stripline transmission lines  264 . Feed line  250 - 1  extends between parallel sheets  224 - 1 B and  224 - 2 A to form the first stripline transmission line  264 , feed line  250 - 2  extends between parallel sheets  224 - 2 B and  224 - 3 A to form a second stripline transmission line  264 , feed line  250 - 3  extends between parallel sheets  224 - 3 B and  224 - 4 A to form a third stripline transmission line  264 , and feed line  250 - 4  extends between parallel sheets  224 - 4 B and  224 - 1 A to form a fourth stripline transmission line  264 . Dielectric rivets or spacers (not shown) may be used to maintain the feed lines  250  at the proper distance from the metal sheets  224  to maintain the proper impedance for the stripline transmission lines  264 . 
     Referring to  FIG.  7 E , first through fourth coaxial feed cables  268 - 1  through  268 - 2  may be used to pass RF signals to and from the radiating element  200 . The outer conductor of the each coaxial feed cable  268  may be soldered or otherwise electrically connected a respective one of the metal sheets  224  adjacent the respective openings  234  in the sheets  224 . The center conductor of each coaxial feed cable  268  may extend through an opening  234  in a sheet  224  and through the opening  263  in a feed stalk  250 . The center conductor of each coaxial feed cable  268  may be soldered to a respective one of the feed lines  250  around the opening  263 . The coaxial feed cables  268  may extend through one or more openings in the reflector  24  to connect to the feed stalk  210 . 
     Referring again to  FIG.  7 A , the radiator unit  260  includes four dipole arms  270 - 1  through  270 - 4 . Each dipole arm  270  may have an identical design, and may be shaped generally in the form of an irregular pentagon. Each dipole arm  270  includes five generally linear segments, namely first and second inner segments  272 ,  274  and first through third outer segments  276 ,  278 ,  280 . 
     In the depicted embodiment, each dipole arm  270  is a planar dipole arm (e.g., a stamped sheet metal dipole arm), although embodiments of the present invention are not limited thereto. For example, in other embodiments, the dipole arms may have downward and/or upward extensions that may allow maintaining a desired physical length for each dipole arm while increasing the distance between dipole arms of adjacent radiating elements. In the depicted embodiment, each dipole arm  270  includes a first inner segment  272  that extends at an angle of +45° and a second inner segment  274  extends at an angle of -45°. The first and second inner segments  272 ,  274  are each narrow segments that have widened distal ends. The first outer segment  276  and the second outer segment  278  are each formed as plates (e.g., rectangular plates) that connect to the distal ends of the first inner segment  272  and the second inner segment 274, respectively. The third outer segment  280  connects the distal end of the first outer segment 276 to the distal end of the second outer segment  278 , and is formed as a narrow metal segment. The first, second and third outer segments  274 ,  276 ,  278  connect to each other at right angles to form three sides of the “rectangle” portion of the irregular pentagon shape formed by each dipole arm  270 , while the first and second inner segments  272 ,  274  form the two sides of the isosceles triangle that extends from the rectangle. Together, the four dipole arms  270  define a cruciform shape when viewed from the front. 
     The dipole arms  270  are arranged so that slots  290  are formed between adjacent dipole arms  270 . In particular, a first slot  290 - 1  is formed between the second inner segment  274  of dipole arm  270 - 1  and the first inner segment  272  of dipole arm  270 - 2 , a second slot  290 - 2  is formed between the second inner segment  274  of dipole arm  270 - 2  and the first inner segment  272  of dipole arm  270 - 3 , a third slot  290 - 3  is formed between the second inner segment  274  of dipole arm  270 - 3  and the first inner segment  272  of dipole arm  270 - 4 , and a fourth slot  290 - 4  is formed between the second inner segment  274  of dipole arm  270 - 4  and the first inner segment  272  of dipole arm  270 - 1 . 
     The radiating element  200  may include capacitive connections between the feed stalk  210  and the dipole arms  270 . The transfer of energy between the feed stalk  210  and the dipole arms  270  may be achieved by capacitive connections that are formed between the plates  232  of feed stalk  210  (each of which is at ground potential) and the plate-like first and second outer segments  274 ,  276  of each dipole arm  270 . A dielectric pad (not shown) may be interposed between the plates  232  and the first and second outer segments  274 ,  276  of each dipole arm  270 . The forward end of each feed stalk  250  is located within a respective one of the slots  290 . When an RF signal is applied to one of the feed lines  250 , the RF energy radiated from the forward end of the feed line  250  generates a voltage differential across its corresponding slot  290 , thereby exciting the dipole arms  270  on either side of the slot  290  to radiate. 
     As shown in  FIG.  7 A , the dielectric spacer  262  may comprise a unitary plastic support that maintains the spacing between adjacent stalk members  220  at a desired distance. The spacer  262  further includes grooves  264  that receive the inner segments  272 ,  274  of the dipole arms  270 . While not shown, additional features may be provided on the spacer  262  that allow the dipole arms  270  to snap in place within the spacer  262 . 
     The radiating element  200  is similar to the radiating element  100  discussed above, except that the capacitive connections between the dipole arms  170  and grounded metal sheets  124  are positioned in the center of radiating element  100 , whereas these connections are at outer portions of the dipole arms  270  in radiating element  270 . The current flow on the dipole arms  270  is the same as shown with respect to radiating element  100  with reference to  FIGS.  6 A and  6 B , and hence further description thereof will be omitted here. 
       FIG.  7 F  is an enlarged perspective view of a bottom portion of the feed stalk 210 when the radiating element  200  is mounted on a reflector  24  of a base station antenna. As shown, an opening  26  may be formed in the reflector  24 . The opening  26  may facilitate forming and/or reworking soldered connections between the coaxial feed cables  268  and the sheets 224 and feed lines  250 . In the depicted embodiment, the opening  26  has a cruciform shape, although other shapes may be used. 
       FIG.  8    is a schematic partial perspective view of a radiating element  300  that is a modified version of the radiating element  200  of  FIG.  7 A . The radiating element  300  differs from the radiating element  200  primarily in that (1) the radiating element  300  includes a “direct” as opposed to a capacitive feed and (2) the radiating element  300  includes “split” feed stalks. 
     As can be seen by comparing  FIGS.  7 A and  8   , the four stalk members  220 - 1  through  220 - 4  (that each comprise an integral pair of forwardly extending metal sheets  224 *A,  224 *B) and four feed lines  250 - 1  through  250 - 4  are replaced in radiating element  300  with four non-integral pairs of forwardly extending metal sheets  324 -*A,  324 *B (the “*” is a wildcard character that represents an integer having a value of 1, 2, 3 or 4). In other words, the feed stalk  310  of radiating element  300  (1) omits the four feed lines  250 - 1  through  250 - 4  of radiating element  200  and (2) uses separate pieces to implement the two metal sheets  324 -* A,  324 -*B of each stalk member  320  instead of using a single bent piece of metal as in radiating element  200 . Because the feed lines  250  are omitted in radiating element  300 , each coaxial feed cable  368  (only the center conductors of the coaxial feed cables  368  are shown in  FIG.  8   ) connects to a forward portion of a first metal sheet  324 -*A of a respective one of the pairs. In particular, the outer conductor of the coaxial feed cable  368  may be soldered to the first metal sheet  324 -*A of the pair, and the center conductor of the coaxial feed cable  368  extends through the first metal sheet  324 -*A of the pair and is electrically connected (e.g., soldered) to the second metal sheet  324 -*B of an adjacent pair, as shown in  FIG.  8   . Thus, in the embodiment of  FIG.  8   , the center conductor of each coaxial feed cable  368  transmits the RF signal directly across a respective one of the slots  390 , thereby generating the voltage differential across the slot  390  to excite the dipole arms  370 . 
     Each coaxial feed cable  368  may extend forwardly from the reflector  24  and may be attached by clips or other fasteners to one of the metal sheets  324  of a pair. The end portion of each coaxial feed cable  368  may be bent 90° and the end of the cable jacket, the outer conductor and the dielectric spacer of each coaxial feed cable  368  may be removed in a fashion well known in the art so that the outer conductor of each coaxial feed cable  368  may be soldered to the other metal sheet  324  of the pair and so that the center conductor of the coaxial feed cable 368 may extend through the opening  334 - 1 A and into the opening  334 - 1 B in a metal sheet 324 of an adjacent pair. 
     It will also be appreciated that the radiating elements according to embodiments of the present invention may have a wide variety of dipole arm designs.  FIGS.  9 A- 9 D  are front views of the dipole arms of radiating elements according to four additional embodiments of the present invention. It will be appreciated that the feed stalk designs for these radiating elements may be similar to the feed stalk  210  of radiating element  200  or to the feed stalk  310  of radiating element  300 , with the primary difference being that the inner and outer segments of each dipole arm may be modified to conform to the shape of the dipole arm and to capacitively couple with one or more widened sections of the dipole arm. 
     Referring to  FIG.  9 A , a radiating element  400 A includes four dipole arms  470 A- 1  through  470 A- 4 . Each dipole arm  470 A is planar and includes a first and second inner segments  472 A,  474 A, and first through third outer segments  476 A,  478 A,  480 A. The five segments of each dipole arm  470 A extend from the center of the radiating element  400 A at the same angles as the corresponding five segments of each dipole arm  270  of radiating element  200  and likewise form an irregular pentagon shape. The dipole arms  470 A differ, however, in that all but the third outer segment  480 A of each dipole arm  470 A are formed as plate-like structures, and the lengths of the first and second inner segments  472 A,  474 A are reduced while the lengths of the first and second outer segments  476 A,  478 A are increased so that the dipole arms  470 A are skinnier (i.e., have a larger aspect ratio) as compared to the dipole arms  270  of radiating element  200 . 
     The radiating element  400 A may have the same size as the radiating element  200  of  FIG.  7 A . For example, radiating elements  200  and  400 A, when viewed from the front, will both have a width and a height of 172 mm each (i.e., the length of each dipole radiator, which comprises two collinear dipole arms, is 172 mm). The radiating element  400 A will exhibit less directivity than the radiating element  200  of  FIG.  7 A  since the current distribution on the dipole arms  470 A of radiating element  400 A is more concentrated in the center of radiating element  400 A, making the overall aperture of radiating element  400 A smaller as compared to radiating element  200  which has the currents spreading more towards the corners of an imaginary square surrounding the overall aperture of the radiating element  200 . 
     Referring to  FIG.  9 B , a radiating element  400 B includes four dipole arms  470 B- 1  through  470 B- 4 . Each dipole arm  470 B may again be a planar structure and may be very similar to the dipole arms  470 A discussed above, with the only difference being that the first and second inner segments  472 B,  474 B and the third outer segment  480 B are shorter segments. As a result of these differences, the first and second outer segments  476 B,  478 B of radiating element  400 B are positioned closer together than the corresponding first and second outer segments  476 A,  478 A of radiating element  400 A. Antennas that include two linear arrays formed using radiating elements  400 B may have improved (narrower) azimuth beamwidth performance and reduced coupling between adjacent linear arrays as compared to an antenna that includes two linear arrays formed using radiating elements  400 A. 
     Referring to  FIG.  9 C , a radiating element  400 C includes four dipole arms  470 C- 1  through  470 C- 4  that each include first and second inner segments  472 C,  474 C and a third outer segment  480 C that together form a triangular shape as opposed to the irregular pentagon shapes of the dipole arms  270 ,  470 A and  470 B discussed above. In the depicted embodiment, the ground connections capacitively couple to the dipole arms at the pads that are provided at the distal ends of the first and second inner segments  472 C,  474 C, and the center conductor connections capacitively couple to the dipole arms  470 C at the pads that are provided at the base ends of the first and second inner segments  472 C,  474 C of the dipole arms  470 C. 
     Referring to  FIG.  9 D , a radiating element  400 D includes four dipole arms  470 D- 1  through  470 D- 4  that each include a plurality of segments that form a “V” shape as opposed to the irregular pentagon shapes of the dipole arms  270 ,  470 A and  470 B discussed above. In the depicted embodiment, the ground connections capacitively couple to the dipole arms at the pads located at the top portions of the V-shape, and the center conductor connections capacitively couple to the dipole arms at the vertex of each V-shaped dipole arm  470 D. 
       FIG.  10 A  is a front view of the dipole arms  570  of a radiating element  500  according to another embodiment of the present invention.  FIG.  10 B  is a perspective view of one of the four feed stalk members  520 - 1  of radiating element  500 . 
     As shown in  FIG.  10 A , each dipole arm  570  may have a generally rectangular shape. Each dipole arm  570  further includes a pair of ground pads  571 ,  573  and a signal pad  575  that serve as locations where the grounded sheets and feed line of the feed stalk members  520  capacitively couple to the dipole arms  570 . Referring to  FIG.  10 B , the feed stalk  510  for radiating element includes four feed stalk member  520 - 1  through  520 - 4 , one of which is shown in  FIG.  10 B . Each feed stalk member  520  may be identical to the corresponding feed stalk members  220  that are discussed above with reference to  FIGS.  7 A- 7 D , except that the shape of the distal end of the feed stalk members  220 ,  520  differ to conform to the shapes of the respective dipole arms  270 ,  570  mounted thereon, as shown in  FIGS.  7 A and  10 B . 
     The radiating elements according to embodiments of the present invention that are discussed above with reference to  FIGS.  7 A- 10 B  each include a feed stalk and a radiator unit having first through fourth dipole arms that are each electrically coupled to the feed stalk. An outer segment of the first dipole arm and an outer segment of the second dipole arm are configured to together form a first radiating structure that radiates at a first polarization, and an outer segment of the third dipole arm and an outer segment of the fourth dipole arm are configured to together form a second radiating structure that radiates at the first polarization, and first and second inner portions of each of the first through fourth dipole arms are configured to together form a third radiating structure that radiates at the first polarization when a first RF signal is fed to the radiating element. The four dipole arms may be arranged to form a cruciform shape. The feed stalks may include first through fourth RF transmission lines or, alternatively, coaxial cables may be connected to the feed stalks that feed the dipole arms without the need for separate RF transmission lines on the feed stalk. 
     In each of these radiating elements, a portion of the first dipole arm extends adjacent to and in parallel to a portion of the second dipole arm to define a first slot, a portion of the second dipole arm extends adjacent to and in parallel to a portion of the third dipole arm to define a second slot, a portion of the third dipole arm extends adjacent to and in parallel to a portion of the fourth dipole arm to define a third slot, and a portion of the fourth dipole arm extends adjacent to and in parallel to a portion of the first dipole arm to define a fourth slot. The RF transmission lines (or coaxial cables), when excited, are configured to apply voltage differentials across the respective first through fourth slots. 
     In each of these radiating elements, the first and third dipole arms may be mounted to extend horizontally in front of a reflector of a base station antenna, and the second and fourth dipole arms are mounted to extend vertically in front of the reflector when a longitudinal axis of the reflector extends in a vertical direction. When mounted in this fashion, the first and third slots will extend at an angle of about -45° with respect to the longitudinal axis of the reflector and the second and fourth slots will extend at an angle of about +45° respect to the longitudinal axis of the reflector. 
     The above described radiating elements may be used in base station antennas. In example embodiments, base station antennas may be provided that include two linear arrays of any of the above-described radiating elements.  FIGS.  11 A- 11 C  are front views of base station antennas that include two arrays of radiating elements according to embodiments of the present invention. 
     Referring to  FIG.  11 A , a base station antenna  600 A includes first and second linear arrays  610 - 1 ,  610 - 2  of radiating elements. Each linear array  610  comprises a column of radiating elements  500 , where each radiating element  500  in an array  610  is aligned along a vertical axis. The linear arrays  610  may extend along either side of the base station antenna  600 A. The radiating elements  500  may be configured to transmit and receive RF signals in some or all of the 617-960 MHz frequency band. The base station antenna  600 A may be relatively wide due to the large footprint of each radiating element  500  (e.g., each radiating element may have a width and a height of 172 mm) and due to the separation between the two linear arrays  610 - 1 ,  610 - 2 , which reduces cross-coupling between the two linear arrays  610 - 1 ,  610 - 2 . 
     In an effort to reduce the width of the base station antenna  600 A, the length of each dipole arm  570  of the radiating elements  500  may be kept as small as possible. As a result, the azimuth beamwidth of the antenna beams generated by the linear arrays  610  may be somewhat large, particularly at the lower end of the 617-960 MHz operating frequency band. This may result in reduced directivity within a sector served by the base station antenna  600  and may also result in increased interference with adjoining sectors. 
       FIG.  11 B  depicts a base station antenna  600 B that is a variant of base station antenna  600 A of  FIG.  11 A . As shown in  FIG.  11 B , the azimuth beamwidth of each linear array  610  may be reduced by horizontally offsetting one or more of the radiating elements  500  in the array from other of the radiating elements  500  in the linear array  610 . In the depicted embodiment, the top radiating element  500  in linear array  610 - 1  is moved inwardly toward the center of the antenna  600 B so that it is horizontally offset with respect to the other two radiating elements  500  in linear array  610 - 1 . Since the radiating elements  500  in linear array  610 - 1  are no longer aligned along a vertical axis, the azimuth beamwidth of the antenna beams formed by linear array  610 - 1  may be narrowed. Likewise, the top radiating element  500  in linear array  610 - 2  is moved inwardly toward the center of the antenna  600 B so that it is horizontally offset with respect to the other two radiating elements  500  in linear array  610 - 2 . This acts to narrow the azimuth beamwidth of the antenna beams formed by linear array  610 - 2 . As is further shown in  FIG.  11 B , the top radiating element  500  in linear array  610 - 1  may be moved downward slightly from the position of the corresponding radiating element  500  in the base station antenna  600 A of  FIG.  11 A , and the top radiating element  500  in linear array  610 - 2  may be moved upward slightly from the position of the corresponding radiating element  500  in the base station antenna  600 A of  FIG.  11 A . This increase the physical distance between the top two radiating elements  500  of base station antenna  600 B, thereby reducing coupling between the two linear arrays  610 - 1 ,  610 - 2 . 
       FIG.  11 C  is a schematic front view of a base station antenna  600 C according to further embodiments of the present invention. Base station antenna  600 C again includes first and second linear arrays  610 - 1 ,  610 - 2  of radiating elements  500 . As shown in  FIG.  11 C , the coupling between the two linear arrays  610 - 1 ,  610 - 2  may be reduced by vertically offsetting the radiating elements  500  in the first linear array  610 - 1  from the radiating elements  500  in the adjacent second linear array  610 - 2 . 
     The cross-dipole radiating elements according to embodiments of the present invention may be inexpensive to manufacture and simple to assemble. 
     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.