Patent Publication Number: US-10326208-B2

Title: Spherical lens array based multi-beam antennae

Description:
This application is a continuation of co-pending U.S. Non-Provisional application Ser. No. 15/698,850, filed Sep. 8, 2017, which is a continuation of co-pending U.S. Non-Provisional application Ser. No. 15/289,531, filed Oct. 10, 2016, which is a continuation of U.S. Non-Provisional application Ser. No. 14/958,607, filed Dec. 3, 2015, which claims the benefit of U.S. Provisional Application No. 62/201,523 filed Aug. 5, 2015. This and all other referenced extrinsic materials are incorporated herein by reference in their entirety. Where a definition or use of a term in a reference that is incorporated by reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein is deemed to be controlling. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention is radio frequency antenna technology. 
     BACKGROUND 
     The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. 
     As the demand for transmission of high quality content across the cellular network increases, the need for better large-scale cellular antennae that support higher capacity rises. The commonly used sector antenna designs have several drawbacks. First, there is a limited number of ports allowed per sector. Second, sector antenna has marginal pattern and beam performance (e.g., poor isolation between beams in the case of multi-beam antennas, side lobes, etc.). 
     It has been proposed that using a spherical lens (e.g., a Luneburg lens, etc.) along with radio frequency transceivers can provide better result than traditional sector antenna. For example, U.S. Pat. No. 5,821,908 titled “Spherical Lens Antenna Having an Electronically Steerable Beam” issued to Sreenivas teaches an antenna system capable of producing independently steerable beams using a phased array antenna and a spherical lens. U.S. Pat. No. 7,605,768 titled “Multi-Beam Antenna” issued to Ebling et al. discloses a multi-beam antenna system using a spherical lens and an array of electromagnetic lens elements disposed around the surface of the lens. 
     However, these antenna systems are not suitable for base station antennae. Thus, there is still a need for effectively utilizing spherical lens in a base station antenna application. 
     All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. 
     SUMMARY OF THE INVENTION 
     In one aspect of the inventive subject matter, an antenna uses an array of spherical lens and mechanically movable elements along the surface of the spherical lens to provide cellular coverage for a narrow geographical area. In some embodiments, the antenna includes at least two spherical lens aligned along a virtual axis. The antenna also includes an element assembly for each spherical lens. Each element assembly has at least one track that curves along the contour of the exterior surface of the spherical lens and along which a radio frequency (RF) element can move. In some embodiment, the track allows the RF element to move in a direction that is parallel to the virtual axis. The antenna also includes a phase shifter that is configured to adjust a phase of the signals produced by the RF elements. The antenna includes a control mechanism that is connected to the phase shifter and the RF elements. The control mechanism is configured to enable a user to move the RF elements along their respective tracks, and automatically configure the phase shifter to modify a phase of the output signals from the elements based on the relative positions between the RF elements. 
     In some embodiments, the tracks also enable the RF elements to move in a direction that is perpendicular to the virtual axis. 
     Multiple RF elements can be placed on a single track. In these embodiments, the multiple RF elements on the same track can be moved independently of each other. In addition, the control mechanism is also programmed to coordinate multiple pairs (or groups) of RF elements and to configure a phase shifter to modify a phase of the output signals transmitted from the same pair (or group) of RF elements, so that the signals would be in-phase. 
     Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates an exemplary antenna system of some embodiments. 
         FIG. 1B  illustrates an exemplary control mechanism. 
         FIGS. 2A and 2B  illustrate the front and back perspectives, respectively, of a spherical lens. 
         FIG. 3  illustrates an alternative antenna system having two-dimensional tracks. 
         FIGS. 4A and 4B  illustrate the front and back perspectives, respectively, of a spherical lens having a two-dimensional track. 
         FIG. 5  illustrates an antenna that pairs opposite RF elements in the same group. 
         FIG. 6  illustrates another antenna that pairs opposite RF elements in the same group. 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the following discussion, numerous references will be made regarding servers, services, interfaces, engines, modules, clients, peers, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor (e.g., ASIC, FPGA, DSP, x86, ARM, ColdFire, GPU, multi-core processors, etc.) configured to execute software instructions stored on a computer readable tangible, non-transitory medium (e.g., hard drive, solid state drive, RAM, flash, ROM, etc.). For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions. One should further appreciate the disclosed computer-based algorithms, processes, methods, or other types of instruction sets can be embodied as a computer program product comprising a non-transitory, tangible computer readable media storing the instructions that cause a processor to execute the disclosed steps. The various servers, systems, databases, or interfaces can exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges can be conducted over a packet-switched network, a circuit-switched network, the Internet, LAN, WAN, VPN, or other type of network. 
     As used in the description herein and throughout the claims that follow, when a system, engine, or a module is described as configured to perform a set of functions, the meaning of “configured to” or “programmed to” is defined as one or more processors being programmed by a set of software instructions to perform the set of functions. 
     The following discussion provides example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed. 
     As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. 
     In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the inventive subject matter are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the inventive subject matter are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the inventive subject matter may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. 
     As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
     Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints and open-ended ranges should be interpreted to include only commercially practical values. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value within a range is incorporated into the specification as if it were individually recited herein. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. 
     All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the inventive subject matter and does not pose a limitation on the scope of the inventive subject matter otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the inventive subject matter. 
     Groupings of alternative elements or embodiments of the inventive subject matter disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims. 
     In one aspect of the inventive subject matter, an antenna uses an array of spherical lens and mechanically movable elements along the surface of the spherical lens to provide cellular coverage for a small, focused geographical area. In some embodiments, the antenna includes at least two spherical lens aligned along a virtual axis. The antenna also includes an element assembly for each spherical lens. Each element assembly has at least one track that curves along the contour of the exterior surface of the spherical lens and along which a radio frequency (RF) element can move. In some embodiment, the track allows the RF element to move in a direction that is parallel to the virtual axis. The antenna also includes a phase shifter that is configured to adjust a phase of the signals produced by the RF elements. The antenna includes a control mechanism that is connected to the phase shifter and the RF elements. The control mechanism is configured to enable a user to move the RF elements along their respective tracks, and automatically configure the phase shifter to modify a phase of the output signals from the elements based on the relative positions between the RF elements. 
       FIG. 1A  illustrates an antenna system  100  according to some embodiments of the inventive subject matter. In this example, the antenna system  100  includes two spherical lenses  105  and  110  that are aligned along a virtual axis  115  in a three-dimensional space. It is noted that although only two spherical lenses are shown in this example, more spherical lens can be aligned along the virtual axis  115  in the antenna system  100 . A spherical lens is a lens with a surface having a shape of (or substantially having a shape of) a sphere. As defined herein, a lens with a surface that substantially conform to the shape of a sphere means at least 50% (preferably at least 80%, and even more preferably at least 90%) of the surface area conforms to the shape of a sphere. Examples of spherical lenses include a spherical-shell lens, the Luneburg lens, etc. The spherical lens can include only one layer of dielectric material, or multiple layers of dielectric material. A conventional Luneburg lens is a spherically symmetric lens that has multiple layers inside the sphere with varying indices of refraction. 
     The antenna system  100  also includes an element assembly  120  associated with the spherical lens  105 , and an element assembly  125  associated with the spherical lens  110 . Each element assembly includes at least one track. In this example, the element assembly  120  includes a track  130  while the element assembly  125  includes a track  135 . As shown, each of the tracks  130  and  135  has a shape that substantially conforms to (curves along) the exterior surface of its associated spherical lens. The tracks  130  and  135  can vary in length and in dimensions. In this example, the tracks  130  and  135  are one-dimensional and oriented along the virtual axis  115 . In addition, each of the tracks  130  and  135  covers less than half of a circle created by the respective spherical lens. However, it is contemplated that the tracks  130  and  135  can have different orientation (e.g., oriented in perpendicular to the virtual axis  115 , etc.), can be two-dimensional (or multi-dimensional), and/or can cover smaller or larger portions of the surface areas of the spherical lenses  105  and  110  (e.g., covering a circumference of a circle created by the spherical lenses  105  and  110 , covering a hemispherical area of the spherical lenses  105  and  110 , etc.). 
     Each of the element assemblies  120  and  125  also houses at least one RF element. An RF element can include an emitter, a receiver, or a transceiver. As shown, the element assembly  120  houses an RF element  140  on the track  130 , and the element assembly  125  houses an RF element  145  on the track  135 . In this example, each of the element assemblies  120  and  125  only includes one RF element, but it has been contemplated that each element assembly can house multiple RF elements on one or more tracks. 
     In some embodiments, each RF element (from RF elements  140  and  145 ) is configured to transmit an output signal (e.g., a radio frequency signal) in the form of a beam to the atmosphere through its corresponding spherical lens. The spherical lens allows the output RF signal to narrow so that the resultant beam can travel a farther distance. In addition, the RF elements  140  and  145  are configured to receive/detect incoming signals that have been focused by the spherical spheres  105  and  110 . 
     Each RF element (of the RF elements  140  and  145 ) is physically connected to (or alternatively, communicatively coupled with) a phase shifter for modifying a phase of the output RF signal. In this example, the RF element  140  is communicatively coupled to a phase shifter  150  and the RF element  145  is communicatively coupled to a phase shifter  155 . The phase shifters  150  and  155  are in turn physically connected to (or alternatively, communicatively coupled with) a control mechanism  160 . 
     In some embodiments, the control mechanism  160  includes a mechanical module configured to enable a user to mechanically move the RF elements  140  and  145  along the tracks  130  and  135 , respectively. The interface that allows the user to move the RF elements can be a mechanical rod or other physical trigger. It is noted that the mechanical rod can have a shape such as a cylinder, a flat piece of dielectric material, or any kind of elongated shapes. In some embodiments, the control mechanism  160  also includes an electronic device having at least one processor and memory that stores software instructions, that when executed by the processor, perform the functions and features of the control mechanism  160 . The electronic device of some embodiments is programmed to control the movement of the RF elements  140  and  145  along the tracks  130  and  135 , respectively. The electronic device can also provides a user interface (e.g., a graphical user interface displayed on a display device, etc.) that enables the user to control the movement of the RF elements  140  and  145 . The electronic device can in turn be connected to a motor that controls the mechanical module. Thus, the motor triggers the mechanical module upon receiving a signal from the electronic device. 
     For example, the control mechanism  160  can move the RF element  140  from position ‘a’ (indicated by dotted-line circle) to position ‘b’ (indicated by solid-line circle) along the track  130 , and move the RF element  145  from position ‘c’ (indicated by dotted-line circle) to position ‘d’ (indicated by solid-line circle) along the track  135 . By moving the RF elements to different positions, the antenna system  100  can dynamically change the geographical coverage area of the antenna  100 . It is also contemplated that by moving multiple RF elements and arranging them in different positions, the antenna system  100  can also dynamically change the coverage size, and capacity allocated to different geographical areas. As such, the antenna system  100 , via the control mechanism  160 , can be programmed to configure the RF elements to provide coverage at different geographical areas and different capacity (by having more or less RF elements covering the same geographical area) depending on demands at the time. 
     For example, as the control mechanism  160  moves the RF elements  140  and  145  from positions ‘a’ and ‘c’ to positions ‘b’ and ‘d,’ respectively, the antenna system  100  can change the geographical coverage area to an area that is closer to the antenna system  100 . It is also noted that having multiple spherical lenses with associated RF element allow the antenna system  100  to (1) provide multiple coverage areas and/or (2) increase the capacity within a coverage area. In this example, since both of the RF elements  140  and  145  associated with the spherical lenses  105  and  110  are directing resultant output signal beams at the same direction as indicated by arrows  165  and  170 , the antenna system  100  effectively has double the capacity for the coverage area when compared with an antenna system having only one spherical lens with one associated RF element. 
     However, it is noted that in an antenna system where multiple spherical lenses are aligned with each other along a virtual axis (e.g., the virtual axis  115 ), when multiple RF elements are transmitting output RF signals through the multiple spherical lenses at an angle that is not perpendicular to the virtual axis along which the spherical lenses are aligned, the signals from the different RF elements will be out of phase. In this example, it is shown from the dotted lines  175 - 185  that the output signals transmitted by the RF elements  140  and  145  at positions ‘b’ and ‘d,’ respectively, are out of phase. Dotted lines  175 - 185  are virtual lines that are perpendicular to the direction of the resultant output signal beams transmitted from RF elements  140  and  145  at positions ‘b’ and ‘d,’ respectively. As such, dotted lines  175 - 185  indicate positions of advancement for the resultant output beams. When the output signal beams are in phase, the output signal beams should have the same progression at each of the positions  175 - 185 . Assuming both RF elements  140  and  145  transmit the same output signal at the same time, without any phase adjustments, the output signal beams  165  and  170  would have the same phase at the time they leave the spherical lenses  105  and  110 , respectively. As shown, due to the directions the beams are transmitted with respect to how the spherical lenses  105  and  110  are aligned (i.e., the orientation of the virtual axis  115 ), the position  175  is equivalent to the edge of the spherical lens  105  for the signal beam  165 , but is equivalent to the center of the spherical lens  110  for the signal beam  170 . Similarly, the position  180  is away from the edge of the spherical lens  105  for a distance ‘e’ while the position  180  is equivalent to the edge of the spherical lens  110 . As such, in order to make the signal beams  165  and  170  in phase, the control mechanism  160  configures the phase shifters  150  and  155  to modify (or adjust) the phase of the output signal transmitted by either RF element  140  or  145 , or both output signals transmitted by RF elements  140  and  145 . In this example, the control mechanism  160  can adjust the phase of the output signal transmitted by RF element  145  by a value equivalent to the distance ‘e’ such that output signal beams  165  and  170  are in-phase. 
     In some embodiments, the control mechanism  160  is configured to automatically determine the phase modifications necessary to bring the output beams in-phase based on the positions of the RF elements. It is contemplated that a user can provide an input of a geographical areas to be covered by the antenna system  100  and the control mechanism  160  would automatically move the positions of the RF elements to cover the geographical areas and configure the phase shifters to ensure that the output beams from the RF elements are in phase based on the new positions of the RF elements. 
       FIG. 1B  illustrates an example of a control mechanism  102  attached to the element assembly  103  that is associated with the spherical lens  107 . The mechanical module  102  includes a housing  104 , within which a rod  106  is disposed. The rod  106  has teeth  108  configured to rotate a gear  112 . The gear can in turn control the movement of the RF element  109 . Under this setup, a person can manually adjust the position of the RF element  109  by moving the rod  106  up and down. It has been contemplated that the rod  106  can be extended to reach other element assemblies (for example, an element assembly and spherical lens that are stacked on top of the spherical lens  107 ). That way, the rod can effectively control the movement of RF elements associated with more than one spherical lens. 
     In some embodiments, a phase shifter can be implemented within the same mechanism  102 , by making at least a portion of the rod  106  using dielectric materials. When the rod includes dielectric materials, adjust the position of the rod  106  in this manner effectively modifies the phase of an output signal transmitted by the RF element  109 . It is noted that one can configure the position of the rod  106  and the gear  112  such that the position of the RF element  109  and the phase modification is in-sync. This way, one can simply provide a single input (moving the rod up or down by a distance) to adjust both the position of the RF element  109  and the phase of the output signal. 
     It is also contemplated that a electric device (not shown) can be connected to the end of the rod (not attached to the gear  112 ). The electric device can control the movement of the rod  106  based on an input electronic signal, thereby controlling the movement of the RF element  109  and the phase adjustment of the output signal. A computing device (not shown) can communicatively couple with the electric device to remotely control the RF element  109  and the phase of the output signal. 
       FIGS. 2A and 2B  illustrate the spherical lens  105  and the element assembly  120  from different perspectives. Specifically,  FIG. 2A  illustrates the spherical lens  105  from a front perspective, in which the element assembly  120  (including the track  130  and the RF element  140 ) appear to be behind the spherical lens  105 . In this figure, the signals emitting from the RF element  140  are directed outward from the page.  FIG. 2B  illustrates the spherical lens  105  from a back perspective, in which the element assembly  120  (including the track  130  and the RF element  140 ) appear to be behind the spherical lens  105 . In this figure, the signals emitting from the RF element  140  are directed into the page. 
       FIG. 3  illustrates an antenna  300  of some embodiments in which the tracks associated with the spherical lens is two dimensional and each track associated with a spherical lens includes two RF elements. The antenna  300  is similar to the antenna  100  of  FIG. 1 . As shown, the antenna  300  has two spherical lenses  305  and  310  aligned along a virtual axis  315  in a three-dimensional space. The spherical lens  305  has an associated element assembly  320 , and the spherical lens  310  has an associated element assembly  325 . The element assembly  320  has a track  330 , and similarly, the element assembly  325  has a track  335 . The tracks  330  and  335  are two dimensional. 
     In addition, each of the tracks  325  and  335  includes two RF elements. As shown, the track  325  has RF elements  340  and  345 , and the track  335  has RF elements  350  and  355 . The two dimensional tracks  330  and  335  allows the RF elements  340 - 355  to move in a two dimensional field in their respective tracks. In some embodiments, the antenna  300  creates groups of RF elements, where each group consists of one RF element from each element assembly. In this example, the antenna  300  has two groups of RF elements. The first group of RF elements includes the RF element  340  of the element assembly  320  and the RF element  350  of the element assembly  325 . The second group of RF elements includes the RF element  345  of the element assembly  320  and the RF element  355  of the element assembly  325 . The antenna  300  provides a control mechanism and phase shifter for each group of RF elements. In this example, the antenna  300  provides a control mechanism and phase shifter  360  (all in one assembly) for the first group of RF elements and a control mechanism and phase shifter  365  for the second group of RF elements. The control mechanism and phase shifters are configured to modify the positions of the RF elements within the group and to modify the phase of the output signals transmitted by the RF elements in the group such that the output signals coming out for the respective spherical lens  305  and  310  are in-phase. 
       FIGS. 4A and 4B  illustrates the spherical lens  305  and its element assembly  320  from different perspectives. Specifically,  FIG. 4A  illustrates the spherical lens  305  from a front perspective, in which the element assembly  320  (including the track  330  and the RF elements  340  and  345 ) appear to be behind the spherical lens  305 . In this figure, the signals emitting from the RF element  340  and  345  are directed outward from the page. As shown, the RF elements  340  and  345  can move up and down (parallel to the virtual axis  315 ) or sideways (perpendicular to the virtual axis  315 ), as shown by the arrows near the RF element  340 . 
       FIG. 4B  illustrates the spherical lens  305  from a back perspective, in which the element assembly  320  (including the track  330  and the RF elements  340  and  345 ) appear to be behind the spherical lens  305 . In this figure, the signals emitting from the RF elements  340  and  345  are directed into the page. It is contemplated that more than two RF elements can be installed in the same element assembly, and different patterns (e.g., 3×3, 4×3, 4×4, etc.) of RF element arrangements can be formed on the element assembly. 
     Referring back to  FIG. 3 , it is noted that the RF elements that are in substantially identical positions with respect to their respective spherical lens are grouped together. For example, the RF element  340  is paired with the RF element  350  because their positions relative to their respective associated spherical lenses  305  and  310  are substantially similar. Similarly, the RF element  345  is paired with the RF element  355  because their positions relative to their respective associated spherical lenses  305  and  310  are substantially similar. It is contemplated that the manner in which RF elements are paired can affect the vertical footprint of the resultant beam (also known as polarized coincident radiation pattern) generated by the RF elements. As defined herein, the vertical footprint of an RF element means the coverage area of the RF element on a dimension that is parallel to the axis along which the spherical lenses are aligned. For practical purposes, the goal is to maximize the overlapping areas (also known as the corss polarized coincident radiation patterns) of the different resultant beams generated by multiple RF elements. 
     As such, in another aspect of the inventive subject matter, an antenna having an array of spherical lenses pairs opposite RF elements that are associated with different spherical lenses to cover substantially overlapping geographical areas. In some embodiments, each spherical lens in the array of spherical lenses has a virtual axis that is parallel with other virtual axes associated with the other spherical lenses in the array. One of the paired RF elements is placed on one side of the virtual axis associated with a first spherical lens and the other one of the paired RF elements is placed on the opposite side of the virtual axis associated with a second spherical lens. In some embodiments, the antenna also includes a control mechanism programmed to configure the paired RF elements to provide output signals to and/or receive input signals from substantially overlapping geographical areas. 
       FIG. 5  illustrates an example of such an antenna  500  of some embodiments. The antenna  500  includes an array of spherical lens (including spherical lenses  505  and  510 ) that is aligned along an axis  515 . Although the antenna  500  in this example is shown to include only two spherical lenses in the array of spherical lenses, it has been contemplated that the antenna  500  can include more spherical lenses that are aligned along the axis  515  as desired. 
     Each spherical lens also includes an RF element arrangement axis that is parallel to one another. In this example, the spherical lens  505  has an RF element arrangement axis  540  and the spherical lens  510  has an RF element arrangement axis  545 . Preferably, the RF element arrangement axes  540  and  545  are perpendicular to the virtual axis  515  along which the spherical lenses  505  and  510  are aligned, as shown in this example. However, it has been contemplated that the RF element arrangement axes can be in any orientation, as long as they are parallel with each other. 
     As shown, each spherical lens in the array has associated RF elements. In this example, the spherical lens  505  has two associated RF elements  520  and  525 , and the spherical lens  510  has two associated RF elements  530  and  535 . The RF elements associated with each spherical lens are placed along the surface of the spherical lens, on different sides of the RF element arrangement axis. As shown, the RF element  520  is placed on top of (on one side of) the RF element arrangement axis  540  and the RF element  525  is placed on the bottom of (on the other side of) the RF element arrangement axis  540 . Similarly, the RF element  530  is placed on top of (on one side of) the RF element arrangement axis  545  and the RF element  525  is placed on the bottom of (on the other side of) the RF element arrangement axis  545 . 
     The antenna  500  also includes control mechanisms  550  and  555  for coordinating groups of RF elements. As mentioned before, it has been contemplated that pairing opposite RF elements that are associated with different spherical lens (i.e., pairing RF elements that are on opposite sides of the RF element arrangement axis) provides the optimal overlapping vertical footprints. Thus, the control mechanism  550  is communicatively coupled with the RF element  520  (which is placed on top of the RF element arrangement axis  540 ) and the RF element  535  (which is placed on the bottom of the RF element arrangement axis  545 ) to coordinate the RF elements  520  and  535  to provide signal coverage of substantially the same geographical area. Similarly, the control mechanism  555  is communicatively coupled with the RF element  525  (which is placed on the bottom of the RF element arrangement axis  540 ) and the RF element  530  (which is placed on top of the RF element arrangement axis  545 ) to coordinate the RF elements  525  and  530  to provide signal coverage of substantially the same geographical area. In some embodiments, the control mechanisms  550  and  555  also include phase shifters configured to modify the phase of the signals being outputted by their associated RF elements. Thus, this embodiment has an antenna assembly that includes a control mechanism but does not include phase shifters. Without phase shifters, the design and operation of the antenna assembly is simplified, but may have signals from output antennas that are slightly out-of phase. 
     In addition to the requirement that the grouped RF elements have to be on different sides of the RF element arrangement axis, it is preferable that the distance between the RF elements and the RF element arrangement axis are substantially the same (less than 10%, and more preferably less than 5% deviation). Thus, in this example, the distance between the RF element  520  and the axis  540  is substantially the same as the distance between the RF element  535  and the axis  545 . Similarly, the distance between the RF element  525  and the axis  540  is substantially the same as the distance between the RF element  530  and the axis  545 . 
     While the RF elements  520 - 535  are shown to be placed at fixed locations in this figure, in some other embodiments, the antenna  500  can also includes tracks that enable the RF elements to move to different positions along the surface of their respective spherical lenses. In these embodiments, the control mechanisms  550  and  555  are configured to coordinate their associated RF elements and phase shifters to send out synchronized signals to a covered geographical area. 
     In the example illustrated in  FIG. 5 , the RF element arrangement axes are arranged to be perpendicular to the axis along which the spherical lenses are aligned. As mentioned above, the RF element arrangement axes can be oriented in different ways.  FIG. 6  illustrates an antenna  600  having RF elements placed on different sides of RF element arrangement axes that are not perpendicular to the virtual axis along which the spherical lenses are aligned. The antenna  600  is almost identical to the antenna  500 . The antenna  600  has an array of spherical lens (including spherical lenses  605  and  610 ) that is aligned along an axis  615 . Although the antenna  600  in this example is shown to include only two spherical lenses in the array of spherical lenses, it has been contemplated that the antenna  600  can include more spherical lenses that are aligned along the axis  615  as desired. 
     Each spherical lens also includes an RF element arrangement axis that is parallel to one another. In this example, the spherical lens  605  has an RF element arrangement axis  640  and the spherical lens  610  has an RF element arrangement axis  645 . As shown, the RF element arrangement axes  640  and  645  are not perpendicular to the virtual axis  615 . By having the RF element arrangement axes in different orientations, the antenna  600  can be adjusted to cover different geographical areas (closer to the antenna, farther away from the antenna, etc.). 
     As shown, each spherical lens in the array has associated RF elements. In this example, the spherical lens  605  has two associated RF elements  620  and  625 , and the spherical lens  610  has two associated RF elements  630  and  635 . The RF elements associated with each spherical lens are placed along the surface of the spherical lens, on different sides of the RF element arrangement axis. As shown, the RF element  620  is placed on top of (on one side of) the RF element arrangement axis  640  and the RF element  625  is placed on the bottom of (on the other side of) the RF element arrangement axis  640 . Similarly, the RF element  630  is placed on top of (on one side of) the RF element arrangement axis  645  and the RF element  625  is placed on the bottom of (on the other side of) the RF element arrangement axis  645 . 
     The antenna  600  also includes control mechanisms  650  and  655  for coordinating groups of RF elements. The control mechanisms  650  and  655  are configured to pair opposite RF elements that are associated with different spherical lens (i.e., pairing RF elements that are on opposite sides of the RF element arrangement axis). Thus, the control mechanism  650  is communicatively coupled with the RF element  620  (which is placed on top of the RF element arrangement axis  640 ) and the RF element  635  (which is placed on the bottom of the RF element arrangement axis  645 ) to coordinate the RF elements  620  and  635  to provide signal coverage of substantially the same geographical area. Similarly, the control mechanism  655  is communicatively coupled with the RF element  625  (which is placed on the bottom of the RF element arrangement axis  640 ) and the RF element  630  (which is placed on top of the RF element arrangement axis  645 ) to coordinate the RF elements  625  and  630  to provide signal coverage of substantially the same geographical area. In some embodiments, the control mechanisms  650  and  655  also include phase shifters configured to modify the phase of the signals being outputted by their associated RF elements. 
     State of art antennas currently used for wireless broadband networks provide two cross polarized coincident radiation patterns commonly referred to as ports of the antenna. There is a growing demand from the wireless operator community for four coincident radiation patterns with good de-correlation of radio signals present on each port. Current approach for four coincident radiation patterns is to deploy redundant cross polarized antenna solutions. The method described above for pairing opposite RF elements provides a novel approach in achieving four predominantly coincident radiation patterns (two for each RF element). 
     It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.