Patent Publication Number: US-2023155699-A1

Title: Methods of storing and retrieving active antenna unit calibration data and related active antenna modules and methods of calibrating same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63/280,301, filed Nov. 17, 2021, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention generally relates to base station antennas that include active antenna modules and, more particularly, to methods of calibrating such active antenna modules. 
     Cellular communications systems are well known in the art. In a typical cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells,” and each cell is served by a base station. The base station may include baseband equipment, radios and base station antennas that are configured to provide two-way radio frequency (“RF”) communications with subscribers that are positioned throughout the cell. A base station antenna includes one or more arrays of radiating elements, where each array is a directional device that can concentrate the RF energy that is transmitted or received in certain directions. The “gain” of an array of radiating elements in a given direction is a measure of the ability of the array to concentrate the RF energy in that direction. The radiation pattern that is generated by an array of radiating elements, which is also referred to as an “antenna beam,” is a compilation of the gain of the array across all different directions. Generally speaking, the more radiating elements included in the array, the greater the ability of the array to concentrate the RF energy that is transmitted or received in desired directions. 
     Base station antennas may include passive antenna arrays and/or active antenna modules. A passive antenna array refers to an array of radiating elements that is configured to generate static antenna beams that have a fixed shape (except for occasional changes to the electronic downtilt angle of the antenna beams) in response to RF signals received from an external radio. The antenna beams generated by a passive antenna array are typically designed to provide coverage to a desired area, such as a sector (e.g., a 120° sector in the azimuth plane) of a cell. In contrast, an active antenna module refers to the combination of a radio unit that includes a beamforming radio and an active antenna unit that includes a multi-column array of radiating elements. The radio unit and the active unit are configured so that together they perform active beamforming. In an active antenna module, the output ports of the beamforming radio are coupled to respective sub-groups of one or more of the radiating elements in the multi-column array of radiating elements. The beamforming radio adjusts the amplitudes and phases of the sub-components of an RF signal that are output at each port of the radio so that the groups of radiating elements work together to, for example, form more focused, higher gain antenna beams that have narrowed beamwidths in the azimuth and/or elevation planes. The electronic adjustment of the amplitudes and phases by the beamforming radio may also be used to “steer” the boresight pointing direction of each generated antenna beam in a desired direction. With active beamforming, the shape of the antenna beams generated by an active antenna module may be varied, for example, on a time slot-by-time slot basis. Active antenna modules may be used as standalone antennas or may be mounted on other antennas (e.g., antennas that include a plurality of passive antenna arrays). 
     Unfortunately, even small unintended variations in the relative amplitudes and phases of the sub-components of an RF signal that are transmitted through an active antenna module can dramatically affect the gain of the resultant antenna beam. Such unintended variations may arise due to static factors (such as small unintended variations in the lengths of the transmission paths between the radio ports and the radiating elements that result in phase variations) or due to dynamic factors (such as non-uniform temperature changes or non-linearities in the amplifiers that are used to amplify the respective transmitted and received signals). When such unintended variations in the relative amplitudes and phases of the sub-components of an RF signal are present, the resulting antenna beams will typically exhibit lower antenna gains in desired directions and higher antenna gains in undesired directions, resulting in degraded performance. 
     In order to reduce the impact of the above-discussed amplitude and phase variations, active antenna modules may include a calibration circuit that samples each sub-component of an RF signal and passes these samples back to the radio. The calibration circuit may comprise a plurality of directional couplers, each of which is configured to tap RF energy from a respective one of the RF transmission paths that extend, for example, between the input ports to an active antenna unit of an active antenna module and the groups of one or more radiating elements thereof, as well as a calibration combiner that is used to combine the RF energy tapped off of each of these RF transmission paths. The output of the calibration combiner is coupled to a calibration port of the active antenna unit, which in turn is coupled back to the radio. The radio may use the samples of each sub-component of the RF signal to determine the actual amplitude and phase of each of the sub-components of the RF signal that are transmitted along the respective RF transmission paths through the active antenna unit, and may then adjust the amplitude and phase weights that are applied in the radio to account for unintended variations from intended values for the amplitude and phase of each of the sub-components of the RF signal. Calibration circuitry may also be provided in the radio unit to detect and compensate for unintended changes in the relative amplitudes and phases of the sub-components of RF signals that are output at each port of the radio unit. 
     An active antenna module can be provided as a single integrated unit or may alternatively be provided as two or more stackable units such as, for example, a radio unit that includes a radio and calibration circuitry and an antenna unit that includes a multi-column active antenna array (e.g., a massive multi-input-multi-output (mMIMO) array of radiating elements) and a filter network, and these units may stackably attach together. In some cases, a single entity may manufacture the entire active antenna module. In other cases, however, different entities may manufacture different components of the active antenna module. For example, in some cases a first entity may manufacture the radio unit and a second entity may manufacture the active antenna unit. 
     SUMMARY 
     Pursuant to embodiments of the present invention, methods of calibrating an active antenna module are provided. The active antenna module may include a radio unit and an active antenna unit. Information is read from an electronically readable data storage device that is mounted on the active antenna unit, and the radio unit is connected to the active antenna unit. A radio of the radio unit is calibrated using the information read from the electronically readable data storage device. 
     In some embodiments, the information read from the electronically readable data storage device may be calibration data for the active antenna unit. This calibration data may be stored in the radio unit. In some embodiments, the calibration data may be amplitude and phase data for each of a plurality of RF transmission paths through the active antenna unit. 
     In some embodiments, the information read from the electronically readable data storage device may be an address of a location where calibration data for the active antenna unit is electronically stored. In such embodiments, the calibration data may be downloaded from the location and stored in the radio unit. The calibration data may be amplitude and phase data for each of a plurality of RF transmission paths through the active antenna unit. 
     In some embodiments, the electronically readable data storage device may be mounted to the active antenna unit using an adhesive. In such embodiments, the electronically readable data storage device may be a barcode sticker or a QR code, and the adhesive may be an adhesive backing on the barcode or QR code sticker. In other embodiments, the electronically readable data storage device may be a near field communication tag. 
     In some embodiments, the electronically readable data storage device may be a barcode or a QR code, and reading information from the electronically readable data storage device may comprise scanning the barcode or the QR code. 
     In some embodiments, the radio unit may include an embedded scanner, and reading information from the electronically readable data storage device may comprise using the embedded scanner to read the information from the electronically readable data storage device. 
     Pursuant to further embodiments of the present invention, active antenna units are provided that comprise an active antenna array, a filter network coupled to the active antenna array, and an electronically readable data storage device mounted on the active antenna unit. Calibration data for the active antenna array or identification of a location where the calibration data for the active antenna array is electronically accessible is stored in the electronically readable data storage device. 
     In some embodiments, the calibration data for the active antenna array may be stored in the electronically readable data storage device. In other embodiments, an address of the location where the calibration data for the active antenna array is electronically accessible may be stored in the electronically readable data storage device. 
     In some embodiments, the calibration data may be amplitude and phase data for each of a plurality of RF transmission paths through the active antenna unit. 
     In some embodiments, the electronically readable data storage device may be mounted to the active antenna unit using an adhesive. 
     In some embodiments, the electronically readable data storage device may be a barcode sticker, and the adhesive may be an adhesive backing on the barcode sticker. In other embodiments, the electronically readable data storage device may be a QR code sticker, and the adhesive may be an adhesive backing on the QR code sticker. In still other embodiments, the electronically readable data storage device may be a near field communication tag. 
     In some embodiments, the active antenna unit may be provided in combination with a radio unit that includes an embedded scanner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic block diagram of an active antenna module according to embodiments of the present invention. 
         FIG.  1 B  is an exploded perspective view of an example implementation of the active antenna module of  FIG.  1 A . 
         FIG.  1 C  is an exploded rear view of a passive base station antenna with the active antenna module of  FIG.  1 B  mounted thereon. 
         FIG.  2 A  is a perspective view of an active antenna unit according to embodiments of the present invention. 
         FIG.  2 B  is a perspective view of a radio unit according to embodiments of the present invention. 
         FIG.  2 C  is a perspective view of the active antenna unit of  FIG.  2 A  mated with the radio unit of  FIG.  2 B . 
         FIG.  3 A  is a front view of a bar code that may be used to store active antenna unit calibration data according to embodiments of the present invention. 
         FIG.  3 B  is a front view of a QR code that may be used to store active antenna unit calibration data according to embodiments of the present invention. 
         FIG.  3 C  is a perspective view of a near field communication tag that may be used to store active antenna unit calibration data according to embodiments of the present invention. 
         FIG.  4    is a flow chart illustrating a method of calibrating an active antenna module according to embodiments of the present invention. 
         FIG.  5    is a schematic block diagram of an active antenna module according to further embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As described above, in some cases, a first entity may manufacture the active antenna unit of an active antenna module, while a second entity may manufacture the radio unit thereof. In many cases, the active antenna unit and the radio unit may each include a calibration port and calibration circuitry, so that the above-described calibration operations may occur to identify the relative amplitude and phase variations along each RF transmission path. However, in some cases, the calibration function will be built into the radio unit, and will be configured to only perform calibration along the transmission paths within the radio unit. As a result, neither the active antenna unit or the radio unit includes a calibration port, and instead the calibration data for the active antenna unit is provided separately to the entity manufacturing the radio unit and is then stored within the radio unit. For example, the calibration data may be sent by email to the entity that manufactures the radio unit or may be uploaded to a secure webpage and the entity manufacturing the radio unit may retrieve the information from the webpage based on the serial number of the active antenna unit. However, these traditional techniques for providing the calibration data to the entity manufacturing the radio unit may be cumbersome and time consuming, and provide opportunities for mistakes that can result in miscalibration of the active antenna module. 
     Pursuant to embodiments of the present invention, improved techniques are provided for a first entity manufacturing an active antenna unit to provide calibration data for the active antenna unit to a second entity that manufactures the radio unit that is deigned to work with the active antenna unit. According to these techniques, the calibration data may be stored in an electronically readable data storage device that is mounted on or within the active antenna unit, or identification information may be stored in the data storage device that can be used to access the calibration data. The electronically readable data storage device may comprise, for example, a barcode, a QR code, or a near field communication tag. The entity manufacturing the radio unit may read the calibration data directly from the data storage device, if it is stored therein, or may read the information that can be used to access the calibration data (e.g., a hyperlink to a specific internet address where the calibration is electronically stored) from the electronically readable data storage device to access the calibration data. The calibration data, whether read directly from the electronically readable data storage device or retrieved from another location based on information read from the electronically readable data storage device, may then be downloaded into a memory of the radio unit so that the calibration operations will take into account the differences in the RF transmission paths through the active antenna unit. 
     According to some embodiments of the present invention, methods of calibrating an active antenna module are provided. The active antenna module may include a radio unit and an active antenna unit. Information is read from an electronically readable data storage device that is mounted on the active antenna unit. The radio unit is connected to the active antenna unit. A radio of the radio unit is calibrated using the information read from the electronically readable data storage device. 
     The information read from the electronically readable data storage device may be calibration data for the active antenna unit or an address of a location where calibration data for the active antenna unit is electronically stored so that the calibration data may be retrieved from that location. Once obtained, the calibration data may be stored in the radio unit. In some embodiments, the calibration data may be amplitude and phase data for each of a plurality of RF transmission paths through the active antenna unit. In some embodiments, the electronically readable data storage device may be mounted to the active antenna unit using an adhesive. In such embodiments, the electronically readable data storage device may be a barcode sticker or a QR code, and the adhesive may be an adhesive backing on the barcode or QR code sticker. In other embodiments, the electronically readable data storage device may be a near field communication tag. 
     According to additional embodiments of the present invention, active antenna unit are provided that comprise an active antenna array, a filter network coupled to the active antenna array, and an electronically readable data storage device mounted on the active antenna unit. Calibration data for the active antenna array or identification of a location where the calibration data for the active antenna array is electronically accessible is stored in the electronically readable data storage device. The electronically readable data storage device may be a barcode, a QR code or an NFC tag in example embodiments, and the data storage device may be implemented as a sticker that is adhered to the active antenna unit. 
     Embodiments of the present invention will now be discussed in further detail with reference to the attached drawings. 
       FIG.  1 A  is a block diagram of an active antenna module  100 . As shown in  FIG.  1 A , the active antenna module  100  includes an active antenna unit  110  and a radio unit  140 . The active antenna unit  110  includes an active antenna array  120 , a filter network  130 , and an electronically readable data storage device  200 . The radio unit  140  includes calibration circuitry  150  and a radio  160 . Outputs of the radio  160  may be coupled to inputs of the filter network  130 , and outputs of the filter network  130  may be coupled to inputs of the active antenna array  120 . 
     The calibration circuitry  150  may be configured to measure the relative amplitudes and phases along at least portions of each RF transmission path in the active antenna module  100 . For example, if the active antenna module  100  is configured to operate as a 64 transmit/64 receive (64T/64R) massive MIMO active antenna, the calibration circuitry  150  may be used to determine the relative amplitudes and phases along at least portions each of the 64 RF transmission paths through the active antenna module  100 . Typically, it is necessary to determine the relative amplitudes and phases along each of the 64 transmission paths at a number of different frequencies throughout the operating frequency band for the active antenna module  100  as the relative amplitudes and phases may vary as a function of frequency. 
     In some active antenna modules, calibration circuitry may be provided in both the radio unit  140  and in the active antenna unit  110 . In such implementations, the radio unit  140  and the active antenna unit  110  may each include one or more calibration ports (not shown) so that calibration signals may be transmitted between the radio unit  140  and the active antenna unit  110 . When such calibration ports are provided, the radio  160  may generate calibration signals that are transmitted through both the radio  160  and the active antenna unit  110  that are used to measure the relative amplitudes and phases along each of the RF transmission paths. In such an arrangement, the calibration circuitry may dynamically calibrate the radio  160  based on changes in the relative amplitude and phases that may occur anywhere along the RF transmission paths (i.e., on portions of the RF transmission paths that are in the radio unit  140  as well as portions that are in the active antenna unit  110 ). 
     The unintended variation in the relative amplitude and phases that may occur along the portions of the RF transmission paths that are in the active antenna unit  110  may tend to be relatively static, as there are no active electronic elements along these portions of the RF transmission paths. While the radio  160  will still require calibration data for the portions of the RF transmission paths in the active antenna unit  110  as manufacturing tolerances will meaningfully impact the relative amplitude and phases, it is typically possible to measure the relative amplitude and phases along each RF transmission path through the active antenna unit  110  one time and to then store that calibration data in the radio unit  460 . This allows the calibration circuit  150  to perform dynamic calibration with respect to the portions of the RF transmission paths in the radio  160 , and to use the static calibration data provided for the portions of the RF transmission paths in the active antenna unit  110  each time calibration is performed. Such a design eliminates the need for calibration ports on the radio unit  140  and the active antenna unit  110 , and also eliminates the need for the calibration circuitry  150  to be partially implemented in the active antenna unit  110 . 
     When dynamic calibration is only performed within the radio  160  and static calibration data is used for the active antenna unit  110 , it is necessary to store the static calibration data for the active antenna unit  110  within the radio unit  140  (or in another location where the data is accessible by the radio  160 ). The techniques according to embodiments of the present invention provide new and improved ways for providing the calibration data to a manufacturer of the radio unit  140 . 
       FIG.  1 B  is an exploded perspective view of an example implementation of the active antenna module  100  of  FIG.  1 A . The active antenna module  100  of  FIG.  1 B  does not include calibration ports on either the active antenna unit  110  or the radio unit  140 . As such, some means for providing calibration data for the active antenna unit  110  is necessary so that such calibration data may be stored in the radio unit  140 . 
     As shown in  FIG.  1 B , the radio unit  140  includes a housing  142  that provides environmental protection to the radio  160  and calibration circuitry  150 . The housing  142  may also include heat dissipation fins  144  or other heat dissipation structures that are used to vent heat generated by the radio  160  from the active antenna module  100 . The radio  160  is mounted within the housing  142 . In the depicted embodiment, the radio  160  comprises circuit elements (not visible in  FIG.  1 B ) that are mounted on a pair of printed circuit boards  162 . Electromagnetic shields  164  are mounted to cover the circuit elements of the radio  160 . RF outputs  166  extend through the electromagnetic shields  164 . The RF outputs  166  may comprise, for example, blind mate coaxial connectors, pogo pin connectors or the like. In the depicted embodiment, each half of the radio  160  includes two columns of RF output pins  166 , where each column has four group of five RF output pins  166 . Four of five the RF output pins  166  in each group may carry RF output signals from the radio  160 , while the fifth output pin  166  is a ground pin  166  that may carry a common electrical ground signal that is associated with all four RF output signals. 
     As is further shown in  FIG.  1 B , the active antenna unit  110  includes the active antenna array  120  and the filter network  130 . The filter network  130  is implemented as a bank of sixteen resonant cavity filter units  132 , where each filter unit  132  includes four separate resonant cavity filters  134 . Each resonant cavity filter  134  has an input  136  (not visible in  FIG.  1 B , but see  FIG.  2 A ) that is coupled to a respective one of the RF output pins  166  of the radio  160 , and each filter unit  134  further includes a ground connection (not shown) that connects to a respective one of the ground pins of the radio  160 . Each filter  134  also includes a filter output  138 . Each filter output  138  is coupled to the active antenna array  120 . The active antenna array  120  includes eight columns of dual-polarized radiating elements  122 . Each column includes a total of twelve radiating elements  122 , and includes three feed board printed circuit boards  124 , where three radiating elements  122  are mounted on each feed board  124  (only one of the feed boards  124  is shown in  FIG.  1 B  to simplify the figure). Each filter output  138  is coupled to a respective pair of feed boards  124  (where the pair of feed boards  124  are adjacent feed boards  124  in the same column) so that the RF signals output through the filter output  138  are coupled to the six radiating elements  122  that are mounted on the pair of feed boards  124 . Two filter outputs  138  are coupled to each pair of feed boards  124 , where the first filter output  138  feeds RF signals to first polarization radiators of the six radiating elements  122  (e.g., −45° dipole radiators) that are mounted on the pair of feed boards  124 , and the second filter output  138  feeds RF signals to second polarization radiators of the six radiating elements  122  (e.g., +45° dipole radiators). While not shown in  FIG.  1 B , the active antenna unit  110  may further include electromechanical phase shifters in some cases that may be used to adjust a downtilt angle of the antenna beams generated by the active antenna unit  110 . 
     The active antenna module  100  may be used as a stand alone antenna. However, in some cases the active antenna module  100  may be mounted on a passive base station antenna  10 , as is shown schematically in  FIG.  1 C , which is an exploded rear view of the passive base station antenna  10  with the active antenna module  100  mounted thereon. 
       FIGS.  2 A- 2 C  are perspective views of the active antenna module  100  of  FIG.  1 B  in various states of assembly. In particular,  FIG.  2 A  is a perspective view of the active antenna unit  110  in its assembled state,  FIG.  2 B  is a perspective view of the radio unit  140  in its assembled state, and  FIG.  2 C  is a perspective view of the active antenna unit  110  mated with the radio unit  140  to form the active antenna module  100 . 
     As shown in  FIG.  2 A , the active antenna unit  110  includes the radome  112  as well as a back plate  114  (which is not shown in  FIG.  1 B ). The radome  112  and the back plate  114  may together form a housing  116 . The active antenna array  120  and the filter network  130  are mounted within the housing  116 . The housing  116  may provide environmental protection to the active antenna array  120  and the filter network  130 . The input ports  136  for the filters  132  may extend through the back plate  114 . As shown in  FIGS.  2 B and  2 C , the radio unit  140  may have a similar size to the active antenna unit  110 . The back plate  114  of the active antenna unit  110  may be mated to the front surface of the radio unit  140  to form the active antenna module  100 . 
     As discussed above, pursuant to embodiments of the present invention, the active antenna unit  110  may include an electronically readable data storage device  200  mounted thereon. The electronically readable data storage device  200  may be mounted on an exterior surface of the housing  116  of active antenna unit  100  in some embodiments, although in other cases it may be mounted within the housing  116 . In some embodiments, the electronically readable data storage device  200  may have calibration data for the active antenna unit  110  stored therein. The calibration data may comprise, for example, amplitude and phase data for each of the sixty-four RF transmission paths through the active antenna unit  110 . As noted above, such amplitude and phase data may be provided for multiple frequencies within the operating frequency band of the active antenna module  100 . The electronically readable data storage device may also include additional information such as, for example, the amplitude and phase weights that will generate certain antenna patterns such as various service beam patterns. The calibration data and other information may be encoded in a specific format in order to minimize the amount of memory required to store the calibration data and other information. 
     While in some embodiments, the calibration data (and any additional information) may be stored in the electronically readable data storage device  200 . However, depending upon the storage capacity of the electronically readable data storage device  200  and the amount of calibration data that must be stored, it may not be possible to fit all of the calibration data within the electronically readable data storage device  200 . In this situation, one solution is to mount multiple electronically readable data storage devices  200  on the active antenna unit  110 , storing a portion of the data in each data storage device. Another solution is to store an identifier in the electronically readable data storage device  200  that at least in part identifies a location where the calibration data is stored. For example, in some embodiments, the identifier may comprise an internet address or a hyperlink that identifies where the calibration data may be accessed. 
       FIGS.  3 A- 3 C  are front views of examples of electronically readable data storage devices according to embodiments of the present invention. As shown in  FIG.  3 A , in some embodiments, the electronically readable data storage device  200  may be implemented as a barcode  200 A. The barcode  200 A may comprise a substrate such as a piece of paper that has a one-dimensional barcode  200 A printed thereon. The one-dimensional barcode comprises a series of bars and spaces of varying width. Several of the bars and spaces on either end of the series of bars and spaces may act as start and stop characters, while the bars and spaces in between the start and stop characters may be used to store data. The barcode may also include one or more bars/spaces that serve as an error detection code (e.g., as a parity bit). The barcode  200 A may be read using a special type of optical scanner known as a barcode reader, that can read the stored data from the barcode  200 A. As described above, the stored data may comprise calibration data for an active antenna unit  110  or an identifier that at least in part identifies where such calibration data is stored. 
     As shown in  FIG.  3 B , in other embodiments, the electronically readable data storage device  200  may be implemented as a QR code  200 B. The QR code  200 B may comprise a substrate such as a piece of paper that has a two-dimensional barcode printed thereon. One-dimensional barcodes such as barcode  200 A typically can store less than one hundred characters of data, and hence their data storage capacity is typically insufficient for storing all of the calibration data. For example, the calibration data may comprise relative amplitude and phase values for sixty-four RF transmission paths, for multiple different frequencies (e.g., ten frequencies). Each amplitude and phase value may comprise, for example, about five characters, meaning that the calibration data in this example may require over six thousand characters. QR codes are two-dimensional structures that can store much larger amounts of data, such as about fifteen hundred characters. Thus, in many cases (and particularly for active antenna arrays having sixteen or thirty-two transmission paths, one or a small number (e.g., two to four) QR codes  200 B may be sufficient to store the calibration data. 
     As shown in  FIG.  3 C , in still other embodiments, the electronically readable data storage device  200  may comprise a near field communication (“NFC”) tag  200 C. NFC tags are passive data storage devices that can store relatively large amounts of data (e.g., between about one thousand and fifteen thousand characters). An NFC scanner can read data from the NFC tag  200 C via inductive coupling. The NFC tag  200 C may comprise an electronic circuit that includes a memory, a radio and an antenna. Each of these components may be formed on a substrate, which can comprise paper or plastic having an adhesive backing so that the NFC tag  200 C may be adhered to another surface (e.g., the housing  116  of the active antenna unit  110 ). 
       FIG.  4    is a flow chart illustrating a method of calibrating an active antenna module according to embodiments of the present invention. As shown in  FIG.  4   , information may be read from an electronically readable data storage device that is mounted on an active antenna unit (Block  400 ). The information that is read from the electronically readable data storage device may comprise, for example, calibration data for the active antenna unit or an address of a location where the calibration data is electronically stored and can be accessed. The information may include additional data such as, for example, optimized amplitude and phase weights for achieving certain antenna patterns. In some embodiments, the information may, for example, be manually read by having a technician use a scanner to read the information from the electronically readable data storage device. In other embodiments, the radio unit of the active antenna module may include an embedded scanner that automatically reads the information from the electronically readable data storage device. 
     As is further shown in  FIG.  4   , the active antenna unit and the radio unit may be mated together to form the active antenna module (Block  410 ). This may be done before or after the calibration data or other information is read from the electronically readable data storage device. If the information stored in the electronically readable data storage device is an address of a location where the calibration data is electronically stored, the calibration data may be accessed from that location. The calibration data may then be stored in the radio unit (Block  420 ). The radio may be calibrated using the information read from the electronically readable data storage device (Block  430 ). 
     Referring to  FIG.  5   , pursuant to further embodiments of the present invention, active antenna modules  300  are provided which include an active antenna unit  310  and a radio unit  340 . The active antenna unit  310  may be identical to the active antenna unit  110  discussed above and hence further description thereof will be omitted here. The radio unit  340  may be similar to the radio unit  140  discussed above, but may further comprise an embedded scanner  370  that is capable of reading the information stored in the electronically readable data storage device  200  that is mounted on active antenna unit  310 . For example, if the electronically readable data storage device  200  is a barcode  200 A or a QR code  200 B, the embedded scanner  370  may comprise an optical scanner. If the electronically readable data storage device  200  is an NFC tag  200 C, the embedded scanner  370  may comprise an NFC reader. The embedded scanner  370  may be mounted in a location where it will be directly adjacent the electronically readable data storage device  200  when the active antenna unit  310  and the radio unit  340  are mated to form the active antenna module  300 . The radio unit  340  may be configured so that the embedded scanner  370  is automatically activated to read the information from any nearby electronically readable data storage device  200  if, for example, certain predetermined conditions are met (e.g., each time the radio  360  is powered on or when the radio  360  is powered on if calibration data has not already been stored in the radio unit  340 ). 
     Having an embedded scanner  370  in the radio unit  340  may be particularly useful in situations where field replacement of part of the active antenna module  300  is required. For example, there may be situations where a wireless operator may wish to replace the active antenna unit  310  of an active antenna module  300  that is already in use in a cellular network. To do so, it would be necessary to remove the entire active antenna module  300  from its mounting location (which is often high on an antenna tower), return the active antenna module  300  to the factory, replace the active antenna unit  310 , download calibration data for the active antenna unit  310  into the radio unit  340 , reassemble the active antenna module  300  and then mount the active antenna module  300  back on the antenna tower. This will often require multiple tower climbs, providing cranes at the antenna tower on multiple locations, both of which can be very expensive. However, if the radio unit  340  has an embedded scanner  370 , the old active antenna unit  310  can be replaced by the new active antenna unit  310  during a single tower climb, and when the active antenna module  300  is turned on the embedded scanner  370  may be used to read the calibration data for the new active antenna unit  310  from the data storage device  200  mounted thereon. Thus, providing an embedded scanner  370  may simplify field replacement of parts of an active antenna module  300 . 
     In the example embodiments discussed above, the filter network is shown as being part of the active antenna unit. It will be appreciated, however, that in other embodiments, the filters may be built into the radio unit, and the active antenna unit may only contain the active antenna array. The techniques described above work equally well with such active antenna modules. In this case, the calibration data may comprise amplitude and phase data for the RF transmission paths through the active antenna array. 
     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.