CN110416706B - Calibration circuit for beam forming antennas and associated base station antennas - Google Patents

Abstract

The present disclosure relates to calibration circuits for beamforming antennas and associated base station antennas. The base station antenna includes a backplane and a plurality of radiating elements extending forward from the backplane. The antenna also includes a plurality of feed plates, and each of the feed plates has a respective set of one or more radiating elements mounted thereon. The antenna also includes a calibration port and a calibration circuit having a calibration combiner having an output coupled to the calibration port and a plurality of directional couplers coupled to the calibration combiner. At least a first portion of a first one of the first directional couplers is implemented on a first one of the feeder boards.

Description

Calibration circuitry for beamforming antennas and associated base station antennas

technical field

The present invention relates to cellular communication systems, and more particularly to cellular communication systems employing beamforming antennas.

Background technique

Cellular communication systems are used to provide wireless communications to fixed and mobile subscribers ("users" herein). In a typical cellular communication system, a geographic area is divided into a series of regions called "cells," and each cell is served by a base station. Each base station may include a baseband device, a radio device, and a base station antenna configured to provide two-way radio frequency ("RF") communication with users within the cell. Base station antennas are typically mounted on towers or other protruding structures.

Base station antennas are directional devices that can focus transmitted or received RF energy in a specific direction. The "gain" of a base station antenna in a given direction is a measure of the antenna's ability to concentrate RF energy in that direction. The radiation pattern (also called "antenna beam") generated by a base station antenna is the sum of the gain of the antenna in all different directions. The radiation pattern of a base station antenna is typically designed to serve a predefined coverage area, such as a cell or a portion of a cell (often referred to as a "sector"). A base station antenna is typically designed to have a minimum level of gain within its predefined coverage area, and a much lower level of gain outside the coverage area to reduce interference to neighboring cells or sectors. Typically, a base station antenna includes one or more phase-controlled arrays of radiating elements arranged in one or more vertical columns when the antenna is installed for use, where "vertical" means generally relative to the The direction perpendicular to the plane.

FIG. 1 is a schematic diagram of a conventional cellular base station 10 . Base station 10 includes several base station antennas 20 mounted on protruding structures 30, such as antenna towers. A baseband unit 40 may be mounted at the base of the tower 30 and a cable connection 42 may connect the baseband unit 40 to a remote radio head (not visible in FIG. 1 ) mounted behind each base station antenna 20 . Each base station antenna 20 may generate an antenna beam 50 (shown schematically in FIG. 1 ) that serves a 120° "sector" in the horizontal or "azimuth" plane. For example, each base station antenna 20 may be designed to have a half-power beamwidth of approximately 65°, which provides good coverage throughout a 120° sector.

Early base station antennas typically had fixed radiation patterns, which meant that once the base station antenna was installed, the radiation pattern of the base station antenna could not be changed unless a technician physically reconfigured the antenna. Today, the radiation pattern on many base station antennas can be changed electronically from a remote location by sending a control signal to the antenna, where the control signal modifies the amplitude and the magnitude of the RF energy sent/received through each radiating element of the array which changes the shape of the radiation pattern. /or phase. The most common variations in the radiation pattern are elevation or "dip" angles (i.e., angles relative to the horizontal plane to which the portion of the antenna beam with the highest gain points) and/or azimuth (the angle at which the portion of the antenna beam with the highest gain points). The angle in the horizontal plane to which the part points). A base station antenna that can have its downtilt and/or azimuth angle changed electronically from a remote location is often referred to as a Remote Electronic Tilt ("RET") antenna.

To increase capacity, some cellular base stations now employ beamforming radios and multiple columns of beamforming antennas. In some beamforming antennas, each column of radiating elements is coupled to a corresponding RF port of a radio. The radio can adjust the amplitude and phase of the subcomponents of the RF signal delivered to each RF port so that the columns of radiating elements work together to form a more focused, higher beam width in the azimuth and/or elevation plane. gain in the antenna beam. In some cases, these beamforming antennas may be used to form two or more static antenna beams, where each antenna beam has a smaller beamwidth in the azimuth plane. This approach can be used to perform so-called "sectorization", where a 120° sector can be divided into two, three, or even more smaller sub-sectors, and the beamforming antennas can be configured such that each Each sub-sector generates a single antenna beam. Beamforming antennas capable of forming narrow antenna beams, sometimes referred to as "pencil beams," which can be directed toward specific users or densely-grouped groups of users, can also be used. These antennas can generate different pencil beams on a slot-by-slot basis so that very high gain antenna beams can be electronically steered across a sector during different slots to provide coverage to users across the sector.

Unfortunately, the relative amplitude and phase imposed by the radio on the subcomponents of the RF signal passed to each column of beamforming antennas is due to the fact that the subcomponents of the RF signal are passed from the radio to the high power amplifier and then onto the base station antenna rather than being maintained. If the relative amplitude and phase change, the resulting antenna beam will typically exhibit lower antenna gain in desired directions and higher antenna gain in undesired directions, resulting in degraded performance. Differences in relative amplitude and phase may arise, for example, due to non-linearities in the amplifiers used to amplify the respective transmit and receive signals, length differences in cable connections between the different radio ports and the corresponding RF ports on the antenna, temperature variations, etc. Variety. While some causes of amplitude and phase variation may tend to be static (ie, they do not change over time), others may be dynamic and thus more difficult to compensate.

To reduce the effects of the aforementioned amplitude and phase variations, beamforming antennas may include calibration circuitry that samples each sub-component of the RF signal and passes these samples back to the radio. The calibration circuit may include a plurality of directional couplers and a calibration combiner, each directional coupler configured to tap from a respective one of the RF transmission paths extending between the RF port and the corresponding column of radiating elements An RF energy, calibration combiner is used to combine the RF energy tapped from each of these RF transmission paths. The output of the calibration combiner is coupled to a calibration port on the antenna, which in turn is coupled back to the radio. The radio may use samples of each subcomponent of the RF signal to determine relative amplitude and/or phase changes along each transmission path, and may then adjust the applied amplitude and phase weights to account for these changes.

Contents of the invention

According to some embodiments of the present invention, there is provided a base station antenna including a backplane and a plurality of radiating elements extending forward from the backplane. The antenna also includes a plurality of feed plates, and each of the feed plates has a respective set of one or more radiating elements mounted thereon. The antenna also includes a calibration port and a calibration circuit having a calibration combiner having an output coupled to the calibration port and a plurality of directional couplers coupled to the calibration combiner. At least a first portion of a first one of the first directional couplers is implemented on a first one of the feeder boards.

According to other embodiments of the present invention, there is provided a base station antenna comprising a backplane, a first plurality of radiating elements arranged to define a first column of radiating elements, and a second plurality of radiating elements arranged to define a second column of radiating elements. Multiple radiating elements. These antennas also include a first electromechanical phase shifter electrically coupled between the first RF port of the antenna and the first column of radiating elements, and a second electromechanical phase shifter electrically coupled between the second RF port of the antenna and the second column of radiating elements. A second electromechanical phase shifter. These antennas also include a calibration circuit comprising coupling along a first RF transmission path extending between the input of the first electromechanical phase shifter and a first of the radiating elements in the first column of radiating elements a first directional coupler, and a first directional coupler coupled along a second RF transmission path extending between the input of the second electromechanical phase shifter and the first radiating element in the radiating elements in the second column of radiating elements Two directional couplers.

According to a further embodiment of the present invention, there is provided a base station antenna comprising a backplane having a front surface and a rear surface, and a plurality of radiating elements extending forward from the backplane. These antennas also include a plurality of feed plates mounted in front of the backplane, wherein each feed plate has a respective set of one or more radiating elements of the plurality of radiating elements mounted on the feed plate. The antenna also includes calibration circuitry including a plurality of components mounted on the front of the backplane and at least one additional component mounted on the back of the backplane.

According to a further embodiment of the present invention there is provided a base station antenna comprising a backplane, a plurality of RF ports comprising at least a first RF port and a second RF port, a plurality of RF ports comprising at least a first radiating element and a second radiating element a radiating element, a plurality of power dividers including at least a first power divider and a second power divider, a calibration port and a calibration circuit, each radiating element extends forward from the backplane, the first power divider is coupled on the first between the RF port and the first radiating element, and the second power divider is coupled between the second RF port and the second radiating element. The calibration circuit includes a calibration combiner and a plurality of directional couplers, the calibration combiner having an output coupled to the calibration port, the plurality of directional couplers including at least a first directional coupler and a second directional coupler coupled to the calibration combiner coupler. The first directional coupler is implemented on a printed circuit board of the first power splitter.

Description of drawings

Figure 1 is a schematic diagram illustrating a conventional cellular base station with three base station antennas for providing coverage to three sectors in an azimuth plane.

2 is a schematic perspective view of a beamforming antenna with a radome removed, according to an embodiment of the present invention.

Fig. 3 is a schematic block diagram illustrating a base station antenna with a conventional calibration circuit.

Fig. 4 is a schematic block diagram illustrating a base station antenna implementing a calibration circuit on a feeder board of the antenna according to an embodiment of the present invention.

Fig. 5 is a schematic block diagram illustrating a base station antenna according to other embodiments of the present invention.

Fig. 6 is a schematic block diagram illustrating a base station antenna according to other embodiments of the present invention.

7 is a schematic diagram illustrating how the directional coupler included in the base station antenna of FIG. 6 can be formed by electromagnetically coupling the RF transmission line on the feed plate to the conductive structure on the underlying calibration circuit board through an opening in the antenna's back plate floor plan.

8 is a schematic front view of a calibration circuit board included in the base station antenna of FIG. 6, illustrating a calibration combiner circuit implemented on the calibration circuit board.

FIG. 9 is a schematic cross-sectional view illustrating another implementation of a directional coupler included in the base station antenna of FIG. 6 .

Fig. 10 is a schematic block diagram illustrating a base station antenna according to a further embodiment of the present invention.

11 is a front perspective view of a phase shifter assembly that may be included in the base station antenna of FIG. 10 .

12 is a schematic block diagram of a modified version of the phase shifter assembly of FIG. 11 that may be used in the base station antenna of FIG. 10 .

Fig. 13 is a schematic block diagram illustrating a base station antenna including a modified version of the calibration circuit included in the base station antenna of Figs. 6-8.

FIG. 14 is a schematic exploded perspective view of a portion of the base station antenna of FIG. 13 .

Figure 15 is a schematic plan view illustrating how a calibration coupler may be implemented on a phase shifter printed circuit board and electromagnetically coupled to a calibration combiner circuit on the calibration circuit board.

Detailed ways

According to an embodiment of the present invention, a beamforming base station antenna with improved calibration circuitry is provided. The calibration circuit may include a plurality of directional couplers and a calibration combiner that combines outputs of the directional couplers. The calibration circuit can be implemented in a new way and at a new location within the antenna, which can provide improved performance and/or reduce the cost of the antenna.

Conventionally, the calibration circuitry for a beamforming antenna is located directly above the antenna's base plate, and an input cable is provided connecting each RF port on the antenna directly to the calibration circuit board on which the calibration circuitry is implemented. A base station antenna with this design can exhibit a high level of tolerance to the calibration circuitry, since the only variations in amplitude or phase within the antenna that will be generated along the calibration path are those that may be introduced in the input cable and/or calibration circuitry. The change. Beamforming base station antennas according to embodiments of the invention may have calibration circuitry located at least partially on the phase shifter printed circuit board, on the feeder board supporting the individual radiating elements, on the power divider printed circuit board, and/or on the duplexer printed circuit board. This new approach allows the calibration circuit to identify relative amplitude and/or phase variations that may be introduced within many antenna feed networks, which allows the radio to correct for such variations and provide improved antenna patterns. Additionally, moving the calibration circuitry to the phase shifter PCB, feeder board, power divider PCB, and/or duplexer PCB moves the calibration circuitry farther away from the RET actuator (typically located with the antenna port adjacent to the base of the antenna), which reduces the possibility of the DC motor included in the RET actuator introducing noise into the calibration circuit. Additionally, relocating the calibration circuitry can also reduce the number of components/circuitry located near the base of the antenna, which can allow for a reduction in the overall length of many antenna designs. Relocating the calibration circuitry can also reduce the number of cables (and associated solder joints) required in the antenna, which can both reduce cost and improve antenna performance. Also, even with a very short microstrip transmission line on the calibration board, the insertion loss added by the microstrip transmission line and the two cables to the microstrip PCB transition can be significant, e.g. about 0.4dB at 3.5GHz magnitude. By locating some or all of the calibration circuitry on the microstrip or other printed circuit board already present in the antenna, this insertion loss can be reduced or eliminated, resulting in improved gain performance. As cellular base stations move to higher frequency bands such as the 3.5GHz and 5GHz bands, it is especially important to improve the efficiency of base station antennas in terms of physical layout and insertion loss performance of next-generation calibration circuits.

In some embodiments of the invention, a monolithic feed plate comprising at least one radiating element from each column of radiating elements included in the antenna may be provided. Calibration circuitry can be fully implemented on this monolithic feeder board. With this design, calibration circuitry can be added to the antenna without increasing the number of connections (eg, solder points or connectors) along the RF signal path through the antenna compared to an antenna that does not include the calibration circuitry. In fact, the only additional connections required to include the calibration circuit are a pair of additional connections connecting the output of the calibration circuit to the calibration port on the antenna. In contrast, adding a calibration circuit board to a conventional antenna typically adds two connections per column of radiating elements, along with two additional connections for connecting the calibration circuit to the calibration port. These additional connections can increase the cost of manufacturing the antenna and are a potential source of passive intermodulation distortion that can degrade antenna performance.

In other embodiments, the calibration circuitry may be more distributed. For example, in one such embodiment, the radiating elements in each column of radiating elements may be mounted on one or more feed plates. One of the feed boards in each column may include a pair of directional couplers for extracting a small amount of energy from the corresponding radiators of the cross-polarized radiating elements mounted on the feed board, and a 2x1 combiner for for combining the two extracted RF signals. The output of the 2x1 combiner may then be coupled to another printed circuit board that includes an Nx1 combiner circuit that combines the outputs of the 2x1 combiner to provide the calibration signal. A connection such as a cable connection may be used to pass the calibration signal output by the Nx1 combiner to the calibration port of the antenna.

In still other embodiments, the first portion of each directional coupler of the calibration circuit can be implemented on one or more of the feed boards, and the second portion of each directional coupler can be implemented on the calibration circuit board superior. Electromagnetic coupling can be used to couple RF energy from the first section to the second section of each directional coupler. In these embodiments, the feed board may be located on the front side of the antenna's back plate, and the calibration circuit board may be located on the back side of the back plate. This approach may allow the use of a small feed board and may reduce the number of solder joints required to implement the calibration circuit.

In still other embodiments, the directional coupler of the calibration circuit may be implemented on the main printed circuit board of the phase shifter included in the antenna to enable remote electronic downtilt. For example, microstrip directional couplers can be implemented along the "input traces" on the main printed circuit board of each phase shifter (ie, the traces that connect the input cables to the power dividers of the phase shifters). Each directional coupler extracts a small amount of RF energy (which may be referred to as an "extracted calibration signal") which is then passed from the phase shifter's printed circuit board to a calibration combiner circuit which combines The extracted calibration signal received from each phase shifter. The output of the calibration combiner circuit can be coupled to the calibration port of the antenna. In an alternate embodiment, the directional couplers can still be implemented on the main PCB of each phase shifter, but after the input RF signal has been subdivided by the power divider circuitry on the phase shifter PCB . For example, a conventional phase shifter for a base station antenna typically divides the input signal into X subcomponents and then applies a variable phase shift to X-1 of these subcomponents. When using such a phase shifter, a directional coupler can be implemented along the transmission path for the non-phase-shifted sub-components of the input signal. As with the above embodiments, each extracted calibration signal can be passed from the phase shifter's printed circuit board to a calibration combiner circuit that combines the extracted calibration signals, and the combined calibration signal can then be passed to the antenna's calibration port .

In still further embodiments, the calibration circuitry may be at least partially implemented on other printed circuit boards within the base station antenna, such as a duplexer printed circuit board or a power divider printed circuit that secures the downtilt base station antenna. plate.

Aspects of the present invention will now be discussed in more detail with reference to FIGS. 2-14 , which illustrate example embodiments of base station antennas including calibration circuitry in accordance with the present invention.

FIG. 2 is a schematic perspective view of a beamforming antenna 100 that may be designed to include any calibration circuitry according to embodiments of the present invention. As shown in FIG. 2 , the beamforming antenna 100 has four rows 110 of dual polarized radiating elements 120 mounted on a planar backplane 102 . Each column 110 of radiating elements 120 has the same azimuth aiming pointing angle. The antenna 100 includes a total of eight RF ports 130, ie, two RF ports 130 for each column (one port for each polarization) and a ninth port 132 for calibration. A radome (not shown) is mounted over the radiating element 120 to provide environmental protection.

FIG. 3 is a schematic diagram illustrating a base station antenna 200 with a conventional calibration circuit. As shown in FIG. 3 , base station antenna 200 includes four columns 210 of dual polarized radiating elements 220 extending forward from backplane 202 . Base station antenna 200 also includes eight RF ports 230 and a calibration port 232 .

An RF signal may be coupled between the RF port 230 and the column 210 of radiating elements 220 . Since dual polarized radiating elements 220 are provided, two RF ports 230 are associated with each column 210, i.e. for the first polarized radiator 222 (e.g. -45° dipole) of the radiating elements 220 in the column 210. A first RF port 230 that feeds and a second RF port 230 that feeds a second polarized radiator 224 (eg, a +45° dipole) of the radiating elements 220 in the column 210 .

Eight input cables 240 , which may be implemented as eg coaxial cables, may be provided connecting each of the RF ports 230 to the calibration circuit board 250 . Typically, each input cable 240 is soldered to a corresponding fixture 252 on the calibration circuit board 250 to provide an electrical path between each input cable 240 and a corresponding RF transmission line 254 on the calibration circuit board 250 .

Each RF transmission line 254 may extend between a respective one of mounts 252 and a respective one of mounts 256 . Each mount 256 may receive a respective one of a plurality of jumper cables 272 extending between the calibration circuit board 250 and a plurality of electromechanical phase shifters 270, as will be discussed in further detail below.

Calibration circuitry 260 is provided on calibration printed circuit board 250 . Calibration circuit 260 may include, for example, a number of directional couplers 262 that may correspond to the number of RF ports 230 (eg, eight directional couplers in the example of FIG. 3 ) and calibration combiners 264 . Each directional coupler 262 may be used to extract a small amount of any RF signal passing along a corresponding one of the RF transmission lines 254 . In the depicted embodiment, each directional coupler 262 is implemented as a trace 263 extending generally parallel alongside a respective one of the RF transmission lines 254 . When an RF signal travels along one of the RF transmission lines 254 , a fraction of the RF energy will electromagnetically couple to the trace 263 such that the trace 263 and adjacent segments of the RF transmission line 254 together form the directional coupler 262 . Trace 263 may be referred to herein as a “tap port” of directional coupler 262 because a small portion of the RF signal traveling along RF transmission line 254 is tapped to trace 263 .

As can also be seen in FIG. 3, calibration combiner 264 is implemented using seven 2x1 combiners 266, which combine any RF signals present at the outputs of eight directional couplers 262 into a single RF signal. As shown, the traces 263 of each set of two adjacent directional couplers 262 are connected to the input of a respective one of the four 2x1 combiners 266 . The fifth 2x1 combiner 266 is used to combine the outputs of the first 2x1 combiner 266 and the second 2x1 combiner 266, and the sixth 2x1 combiner 266 is used to combine the outputs of the third 2x1 combiner 266 and the fourth 2x1 combiner 266 . The seventh 2x1 combiner 266 combines the outputs of the fifth 2x1 combiner 266 and the sixth 2x1 combiner 266 . Each 2x1 combiner 266 can be implemented using any conventional power coupler. For example, combiner 266 may be implemented using a Wilkinson power coupler. The output of the seventh 2x1 combiner 266 is connected to the calibration fixture 253 and a calibration cable 280 connects the calibration fixture 253 to the calibration port 232 on the antenna 200 .

Each mount 256 on the calibration circuit board 250 houses a respective jumper cable 272 connecting the mount 256 to a respective one of the plurality of phase shifters 270 . The phase shifter 270 is configured to split the RF signal provided at its input port 274 into a plurality of sub-components and then apply an adjustable phase taper to the RF sub-components. The output of each phase shifter 270 is connected to the feed plate 212 of the corresponding column 210 of radiating elements to allow RF signals to pass between the phase shifter 270 and the feed plate 212 . Each column 210 has an associated first polarization phase shifter 270 and an associated second polarization phase shifter 270 . The first polarization phase shifter 270 for each column has a connection (via three corresponding phase cables 276) to a corresponding RF transmission line 214 provided on each of the three feed boards 212 in the column 210. Three output terminals. Each RF transmission line 214 passes through a corresponding splitter 216 so that the RF transmission line 214 can be connected to the first polarized radiator 222 of each of the two radiating elements 220 mounted on the feeder board 212 . In this way, each output terminal of the first polarization phase shifter 270 can be connected to the first polarization radiators 222 of the two radiating elements 220 on a corresponding one of the feed boards 212 . Similarly, the second polarization phase shifter 270 for each column 210 has a connection (via a corresponding phase cable 276) to a corresponding RF transmission line provided on each of the three feeder boards 212 in the column 210 215's three outputs. Each RF transmission line 215 passes through a corresponding splitter 217 so that the RF transmission line 215 can be connected to the second polarized radiator 224 of each of the two radiating elements 220 mounted on the feeder board 212 . In this way, each output terminal of the second polarization phase shifter 270 can be connected to the second polarization radiators 224 of the two radiating elements 220 on a corresponding one of the feed boards 212 .

As discussed above, the calibration circuit 260 is used to identify any undesired variations in the amplitude and/or phase of the RF signals input to the various RF ports 230 of the beamforming antenna 200 . In particular, calibration circuitry 260 extracts a small amount of each of the RF signals input to antenna 200, and then combines these extracted "calibration" signals and passes them back to the radio generating the RF signals. The radio may use this information to ensure that the amplitude and phase weights applied to the RF signals sent to the various columns 210 of radiating elements 220 provide optimized antenna beams.

The calibration circuit 260 in the base station antenna 200 may allow the use of a short input cable 240 because the calibration circuit board 250 may be located in close proximity to the RF port 230 . Furthermore, the calibration circuit 260 can easily pass the tolerance test since the short input cable 240 should exhibit little variation. However, the conventional calibration circuit design shown in FIG. 3 suffers from several disadvantages. First, this design positions the calibration circuit board 250 adjacent to the RF port 230 at the base of the antenna 200, which is also the traditional location for the RET actuator. The current trend for base station antennas is to include a large number of independently controlled phase shifters, and thus many antennas include six, twelve or even more independently controlled phase shifters, requiring a corresponding number of RET actuators. As a result, antenna designers typically need to position a large number of RET actuators near the base of the antenna, which often requires extending the length of the antenna. However, increasing the length of the antenna generally has negative consequences in terms of cost, weight and customer satisfaction.

Additionally, RET actuators typically include DC motors. When the motors are operating, they may generate noise that negatively affects the RF signal on the calibration circuit board, especially since the calibration circuit board is often implemented as an unshielded microstrip printed circuit board. Also, while conventional calibration circuits are good at identifying amplitude and phase variations that may occur for RF signals passing along each RF transmission path between the radio and the antenna, conventional calibration circuits are not sensitive to RF signals passing through the feed of the base station antenna. Little to no identification is made of the amplitude and phase changes that occur in the electrical network. So if there are such variations (e.g. temperature variations affecting relative phase due to part of the antenna being in sunlight and the rest in shade), then the amplitude and phase weights used to perform beamforming may not be ideal , resulting in degradation of the antenna pattern.

Finally, as shown in FIG. 3 , typically two cable connections per column are made to the calibration circuit board 250 and another two cable connections for the calibration cable 280 , resulting in eighteen additional connections in the antenna 200 point. Each connection point is usually made by soldering one end of the cable to the printed circuit board. However, these soldered connections are time consuming to implement and are a potential source of passive intermodulation distortion ("PIM"). Calibration circuit designs according to embodiments of the present invention may reduce the number of solder joints required and/or may overcome other disadvantages associated with conventional calibration circuit designs.

FIG. 4 is a schematic diagram illustrating a base station antenna 300 according to an embodiment of the present invention. As shown in FIG. 4 , base station antenna 300 includes four columns 310 of dual polarized radiating elements 320 . Each radiating element 320 may be mounted to extend forwardly from the backplane 302 . Any suitable radiating element may be used. In an example embodiment, each radiating element 320 may include a pair of stalks, such as two printed circuit boards extending forward from the backplane 302, having a pair of dipole radiators 322, 324 formed or mounted thereon. (Only dipole radiators 322, 324 are shown in FIG. 4). The circuit can be arranged in an "X" configuration, and the radiators 322, 324 can be arranged in a "crossed-dipole" arrangement, where the first radiator 322 is placed at an angle of -45° to the vertical axis, and the second radiator 324 Positioned at +45° to the vertical axis, the two radiators 322, 324 will radiate with orthogonal polarizations.

Backplane 302 may comprise a single structure or may comprise multiple structures attached together. Backplane 302 may include, for example, a reflector that acts as a ground plane for dual polarized radiating element 320 . Each column 310 of radiating elements 320 may be oriented generally vertically with respect to a horizontal plane when base station antenna 300 is installed for use. In the depicted embodiment, each column 310 includes a total of six radiating elements 320 . However, it will be appreciated that other numbers of radiating elements 320 may be included in each column 310 and that different numbers of columns 310 may be included in antenna 300 . The same is true for the embodiments of the invention discussed herein.

Base station antenna 300 includes eight RF ports 330 and a calibration port 332 . Each RF port 330 may be coupled to a corresponding port of a multi-port radio (not shown) via a jumper cable (not shown). The RF port 330 may eg be mounted in a substrate of the housing of the antenna 300 . RF signals are coupled between RF port 330 and column 310 of radiating elements 320 . Since dual polarized radiating elements 320 are provided, two RF ports 330 are associated with each column 310, i.e., to the first polarized radiator 322 (e.g., -45° dipole) of the radiating elements 320 in the column 310 A first RF port 330 feeds and a second RF port 330 feeds a second polarized radiator 324 (eg, a +45° dipole) of the radiating elements 320 in the column 310 .

Eight input cables 340 , which may comprise, for example, coaxial cables, are provided connecting each of the RF ports 330 to a respective one of the plurality of electromechanical phase shifters 370 . Each electromechanical phase shifter 370 is configured to split the RF signal provided at its input port 374 (using one or more power dividers such as directional couplers) into multiple subcomponents and apply an adjustable phase taper to Subcomponents. The amount of phase taper can be adjusted by mechanically changing the setting of the electromechanical phase shifter 370 . Since the calibration circuit board for the antenna 300 is not located on the electrical path between the RF port 330 and the corresponding phase shifter 370, the antenna 300 can be shortened compared to the antenna 200, as schematically shown in FIG. 4 .

The phase shifters 370 can be implemented, for example, using "wiper" phase shifters, each comprising a main printed circuit board and a "wiper" printed circuit that can rotate over the main printed circuit board. plate. The wiper phase shifter may divide the input RF signal received at the main printed circuit board into a plurality of subcomponents and then capacitively couple at least some of the subcomponents to the wiper printed circuit board. Further subdivision of the RF signal can be done on the wiper PCB. Subcomponents of the RF signal can be capacitively coupled from the wiper printed circuit board back to the main printed circuit board along a plurality of arcuate traces, each arc having a different diameter. Each end of each arcuate trace may be connected to a radiating element or a subgroup of radiating elements. By physically (mechanically) rotating the wiper PCB over the main PCB, the position at which subcomponents of the RF signal are capacitively coupled back to the main PCB can be changed, which in turn changes the slave phase for each subcomponent of the RF signal The length of the corresponding transmission path from the shifter to the associated radiating element. Variations in these path lengths result in phase changes in the corresponding subcomponents of the RF signal, and since the arcs have different radii, the phase changes along different paths will be different. Typically, by applying a positive phase shift of various magnitudes (e.g., +X°) to one or more subcomponents of the RF signal and by applying a negative phase shift of the same magnitude to one or more other subcomponents of the RF signal Phase taper is applied by shifting (for example, -X°). Additionally, the phase shifter 370 typically includes a transmission path that is not coupled to the wiper printed circuit board and therefore does not undergo an adjustable phase change. The wiper printed circuit board may be moved using an electromechanical actuator such as a DC motor connected to the wiper printed circuit board via a mechanical linkage.

Still referring to FIG. 4 , the radiating element 320 is mounted on a plurality of feeder boards 312 , 313 . In the exemplary embodiment shown in FIG. 4, each feed plate 312 has two radiating elements 320 mounted thereon. The two radiating elements 320 at the top of each column 310 are mounted on a feed board 312 and the two radiating elements 320 at the bottom of each column 310 are mounted on another feed board 312 . The feed plate 313 is a larger feed plate on which eight radiating elements 320 (ie, the middle two radiating elements 320 for each of the four columns 310 ) are mounted. The feed board 313 functions as both a feed board including an RF transmission line connected to the radiating element 320 mounted on the feed board 313 and as a calibration circuit board including the calibration circuit 360 . Eight phase cables 376 are provided which connect the first output of each phase shifter 370 to one of the feeder boards 312 at the top of the quad columns 310 (each feeder board 312 is connected by two phase cables 376 feed, each phase cable 376 for one of the two polarizations). Another eight phase cables 376 connect the second output of each phase shifter 370 to the feed board 313, and another set of eight phase cables 376 connect the third output of each phase shifter 370 to the One of the feeder boards 312 at the bottom of the column 310 . The three outputs of each first polarization phase shifter 370 are coupled to the first polarization radiators 322 of the six radiating elements in a corresponding column in column 310, and the three outputs of each second polarization phase shifter 370 End-coupled to the second polarizing radiators 324 of the six radiating elements in a corresponding one of the columns 310 . In some embodiments, the output of the phase shifter 370 connected to the feed board 313 may be the output of the phase shifter 370 not subject to an adjustable phase shift.

The feed board 312 may be the same as the feed board 212 described above with respect to FIG. 3 . Specifically, each feed plate 312 may include a first RF transmission line 314 coupled to one of the outputs of a corresponding one of the first polarization phase shifters 370, and coupled to a second polarization phase shifter The second RF transmission line 315 at one of the outputs of a corresponding one of the second polarization phase shifters in the device 370. On each feeder board 312, a first RF transmission line 314 is coupled to a first splitter 316, and the output of the first splitter 316 is connected to one of the two radiating elements 320 mounted on the feeder board 312. A first polarized radiator 322 for each radiating element. Likewise, the second RF transmission line 315 is coupled to the second splitter 317, and the output of the second splitter 317 is connected to the second of each of the two radiating elements 320 mounted on the feeder board 312. polarizing radiator 324 .

For each pair of radiating elements 320 installed on the feeding board 313, the feeding board 313 also includes a first RF transmission line 314 and a second RF transmission line 315 and a first splitter 316 and a second splitter 317, which are connected with The feed plates 312 are connected in the same way, the only difference being that a single large feed plate 313 is provided for eight radiating elements 320 instead of four smaller feed plates 312 .

A calibration circuit 360 is also provided on the feed board 313 . Calibration circuit 360 may include, for example, a number of directional couplers 362 that may correspond to the number of RF ports 330 (eg, eight directional couplers 362 ) and a calibration combiner 364 . Each directional coupler 362 may be used to extract a small amount of any RF signal passing along a respective one of the RF transmission lines 314 , 315 . In the depicted embodiment, each directional coupler 362 is implemented as a trace 363 extending generally parallel alongside a respective one of the RF transmission lines 314 , 315 . When an RF signal travels along one of the RF transmission lines 314, 315, a fraction of the RF energy will electromagnetically couple to the trace 363 of the directional coupler 362 formed along the RF transmission line 314, 315. Trace 363 may be referred to herein as a “tap port” of directional coupler 362 because a small portion of the RF signal traveling along RF transmission lines 314 , 315 is tapped to trace 363 .

Calibration combiner 364 is implemented using seven 2x1 combiners 366 that combine any RF signals present at the outputs of eight directional couplers 362 into a single RF signal. Traces 363 of each set of two adjacent directional couplers 362 are connected to the inputs of four 2x1 combiners 366 as shown. The fifth 2x1 combiner 366 is used to combine the outputs of the first 2x1 combiner 366 and the second 2x1 combiner 366, and the sixth 2x1 combiner 366 is used to combine the outputs of the third 2x1 combiner 366 and the fourth 2x1 combiner 366 . The seventh 2x1 combiner 366 combines the outputs of the fifth 2x1 combiner 366 and the sixth 2x1 combiner 366 . Each combiner 366 may be implemented using any conventional power coupler. For example, combiner 366 may be implemented using a Wilkinson power coupler. The output of the seventh 2x1 combiner 366 is connected to the calibration fixture 353 and a calibration cable 380 connects the calibration fixture to the calibration port 332 on the antenna 300 .

Accordingly, the base station antenna 300 includes a backplane 302 and a plurality of radiating elements 320 extending forwardly from the backplane 302 . The antenna 300 also includes a plurality of feed plates 312, 313, and each of the feed plates 312, 313 has a respective set of one or more radiating elements 320 mounted thereon. The antenna 300 also includes a calibration port 332 and a calibration circuit 360. The calibration circuit 360 has a calibration combiner 364 and a plurality of directional couplers 362. The calibration combiner 364 has an output coupled to the calibration port 332. The plurality of directional couplers 362 are coupled to Calibration combiner 364 . At least a first part of the first directional couplers of the first directional couplers 362 is implemented on the feeder board 313 .

The radiating elements 320 are arranged to define a first column 310 of radiating elements 320 and a second column 310 of radiating elements 320 . The antenna 300 also includes a first electromechanical phase shifter 370 electrically coupled between the first RF port 330 of the antenna 300 and the first column 310 of radiating elements 320, and electrically coupled between the second RF port 330 of the antenna 300 and the radiating elements. The second electromechanical phase shifter 370 between the second column 310 of 320 . The calibration circuit 360 includes a first directional coupler coupled along a first RF transmission path extending between an input of a first electromechanical phase shifter 370 and a first of the radiating elements 320 in the first column 310 362 , and a second directional coupler 362 coupled along a second RF transmission path extending between the input of the second electromechanical phase shifter 370 and the first of the radiating elements 320 in the second column 310 .

The calibration circuit 360 is used to identify any undesired variations in the amplitude and/or phase of the RF signals input to the different RF ports 330 of the beamforming antenna 300 . In particular, calibration circuitry 360 couples a small number of RF signals input to antenna 300 through each RF port 330, and then combines these extracted "calibration" signals and passes them back to the radio generating the RF signals. When performing a calibration operation, the radio may send to each RF port 330 RF signals at different frequencies or RF signals each including a unique code, so that a receiver at the radio can distinguish the received calibration signals to determine each RF port 330. The relative amplitude and phase of each calibration signal. The radio may use this information to ensure that the amplitude and phase weights applied to the RF signals sent to the various columns 310 of radiating elements 320 provide optimized antenna beams.

Calibration circuit 360 may have several advantages over prior art calibration circuits. First, the calibration circuit board 313 is removed from the RF port 330 . This reduces the effect that the RET actuator may have on the calibration circuitry and also reduces the number of components located at the base of the antenna 300 . This can allow for shorter antennas. Furthermore, since the calibration circuit board is located on the feed board, the calibration circuit 360 can also identify amplitude and phase variations that occur in the feed network of the antenna 300, and thus the radio can adjust the amplitude and phase weights to correct for any such variations , allowing improved beamforming. Also, as can be seen by comparing FIGS. 2 and 3, antenna 300 includes eight fewer cables (i.e., jumper cable 272 of antenna 200 is not included in antenna 300), and thus sixteen fewer cables may be required in antenna 300. solder joints. Solder joints are time consuming to complete in fabrication and are a potential source of passive intermodulation distortion. Accordingly, base station antenna 300 is less expensive to manufacture and may provide improved performance compared to prior art base station antennas.

FIG. 5 is a schematic diagram illustrating a base station antenna 400 according to other embodiments of the present invention. As will be apparent from the description below, base station antenna 400 includes attributes of conventional base station antenna 200 as well as base station antenna 300 .

Base station antenna 400 includes four columns 410 of dual polarized radiating elements 420 having first radiators 422 and second radiators 424 . Radiating elements 420 are mounted on a plurality of feeder boards 412 , 413 . Each radiating element 420 extends forwardly from the backplane 402 . Base station antenna 400 also includes eight RF ports 430 and a calibration port 432 . Input cables 440 connect each RF port 430 to a respective one of a plurality of electromechanical phase shifters 470 , and phase cables 476 connect the outputs of the phase shifters 470 to feed boards 412 , 413 . Backplane 402, radiating element 420, RF port 430, calibration port 432, input cable 440, phase shifter 470, and phase cable 476 can be compared to backplane 302, radiating element 320, RF port 330, calibration port 332, input Cable 340, phase shifter 370, and phase cable 376 are identical, so further description thereof will be omitted here. Base station antenna 400 also includes calibration circuitry 460, which will be described in more detail below.

Each feed plate 412, 413 may have two radiating elements 420 mounted thereon. The feed board 412 may be the same as the feed board 312, and thus further description thereof will be omitted here. The feed board 413 in combination with the calibration circuit board 450 provides a different way of implementing a calibration circuit along the electrical path between the phase shifter and the radiating element of the base station antenna.

In particular, four small feed plates 413 are provided in the base station antenna 400 compared to the larger feed plates 313 included in the base station antenna 300 . Each feed plate 413 includes a first RF transmission line 414 coupled to one of the outputs of a corresponding one of the first polarization phase shifters 470, and a first RF transmission line 414 coupled to one of the outputs of the second polarization phase shifter 470. A second RF transmission line 415 corresponding to one of the output terminals of a second polarization phase shifter. The first RF transmission line 414 is coupled to a first splitter 416, and the output of the first splitter is connected to the first polarized radiator of each of the two radiating elements 420 mounted on the feeder board 413 422. Likewise, the second RF transmission line 415 is coupled to a second splitter 417, and the output of the second splitter 417 is connected to the second of each of the two radiating elements 420 mounted on the feeder board 413. polarizing radiator 424 .

Additionally, each feed board 413 includes a portion of a calibration circuit 460 . As in other embodiments discussed herein, the calibration circuit 460 may include eight directional couplers 462 for dividing the RF energy input from each RF port 430 of the antenna 400 into eight directional couplers 462 and a combiner circuit 464. Taking a fraction, combiner circuit 464 combines the tapped RF energy into a single composite RF signal. The directional coupler 462 may be implemented in the same manner as the directional coupler 362 described above, ie, as traces 463 running approximately parallel beside respective ones of the RF transmission lines 414 , 415 . As shown in FIG. 5 , each feeder board 413 includes two directional couplers among directional couplers 462 for tapping the radiating element 420 that is fed to each feeder board 413 A fraction of the RF energy of the corresponding first radiator 422 and second radiator 424 . In some embodiments, the output of the phase shifter 470 connected to the feed board 413 may be the output of the phase shifter 470 that is not subject to an adjustable phase shift. The directional coupler 462 may be the same as the directional coupler 362 described above, and thus further description thereof will be omitted. The tap ports of the two directional couplers 462 on each feed board 413 are input to a 2x1 combiner 466 formed on the feed board 413, which combines the two tapped RF signals into composite signal. The output of each "feed board" 2x1 combiner 466 may be coupled to the calibration circuit board 450 by a cable connection (or some other suitable transmission line structure).

The calibration circuit board 450 may include three additional 2x1 combiners 466 (or a single 4x1 combiner) that combine the outputs of the four 2x1 combiners 466 provided on the respective feeder boards 413 . Seven 2x1 combiners 466 may be arranged in the same manner as combiners 366 , except that 2x1 combiners 466 are distributed over multiple circuit boards 413 , 450 , and combiners 366 are all implemented on the same calibration circuit board 313 . 2x1 combiner 466 may be implemented in the same manner as combiner 366 (e.g., as a Wilkinson power combiner) and the output of the last 2x1 combiner 466 in the tree structure may be electrically connected to calibration port 432 via calibration cable 480 .

It is clear that the calibration circuit 460 is similar to the calibration circuit 360 described above, with the main difference being that the one large circuit board 313 included in the base station antenna 300 is replaced by four smaller feed boards 413 and Small calibration circuit board 450 . This approach eliminates the need for a large circuit board (which tends to be expensive) and allows feeder board 413 to be very similar to feeder board 412, which can simplify the design process. Furthermore, it should be noted that the feed boards (eg, feed boards 312, 313, 412, 413) are typically mounted on the front side of the antenna's backplane. Therefore, radiation emitted by the antenna's radiating element may be incident on the feed plate, potentially injecting noise into the calibration signal. In base station antenna 400 , calibration circuit board 450 may be mounted on the rear side of backplane 402 , where backplane 402 shields circuitry on the backplane from RF energy emitted by radiating element 420 . Thus, since a portion of the calibration circuit 460 is mounted behind the backplane 402, the calibration circuit 460 in the base station antenna 400 may have reduced susceptibility to such RF noise. However, the base station antenna 400 may include four more cable connections (and thus eight more solder joints) than the base station antenna 300 because the cable connections may be used to connect the four feed boards 413 The output of each 2x1 combiner 466 on the circuit board 450 is connected to the calibration circuit.

FIG. 6 is a schematic diagram illustrating a base station antenna 500 according to other embodiments of the present invention. Base station antenna 500 may combine some of the advantages provided in base station antenna 300 and base station antenna 400 described above. Therefore, the following description will focus on the differences between the base station antenna 500 and the above-mentioned base station antenna 300 and base station antenna 400 .

As shown in FIG. 6 , the base station antenna 500 includes four feeding boards 513 and a calibration circuit board 550 . In addition to the feed board 513 may be designed to facilitate coupling of RF energy from the RF transmission lines 514, 515 formed on the feed board to traces on the calibration circuit board 550 (or other structure) through openings in the backplane 502 Otherwise, the feed board 513 may be similar to the conventional feed board 212 .

7 is an enlarged schematic front view of one of the feed boards 513 and a portion of the backplane 502 and the calibration circuit board 550 positioned behind the feed board 513, which better illustrates the Design and operation of calibration circuit 560 included. FIG. 8 is a schematic front view illustrating a calibration circuit board 550 on which a calibration combiner circuit 564 is implemented. It should be noted that, in order to simplify the drawing, FIG. 6 does not illustrate the various circuit elements included on the calibration circuit board 550 , but these circuit elements are shown in FIG. 8 .

Referring to FIGS. 6-8 , the back plate 502 may have a pair of openings 504 behind each feed plate 513 . Calibration circuit board 550 is positioned behind backplane 502 . A pair of RF transmission lines 514, 515 provided on each feed plate 513 to carry the RF energy output from the phase shifter 570 to the respective first radiator 522 and second radiator 524 of the radiating element 520 may, for example, be included on the back Segment 518 extending from the backside of feeder plate 513 near opening 504 in plate 502 . The calibration circuit board 550 may include a conductive structure 552 such as, for example, a widened mesa of conductive pads immediately behind each opening 504 in the backplane 502 . Thus, RF energy present on one of the segments 518 may be electromagnetically coupled from the segment 518 to the corresponding conductive structure 552 through the opening 504 in the backplate 502 . Accordingly, it should be appreciated that each combination of segment 518 and conductive structure 552 forms a directional coupler 562 that taps a fraction of the RF energy flowing on a respective one of RF transmission lines 514 . Thus, in the embodiment of FIG. 6 , the directional coupler 562 of the calibration circuit 560 is implemented as an electromagnetic coupling between different circuit board structures.

As shown in FIG. 8 , a calibration combiner 564 is formed on the calibration circuit board 550 . The calibration combiner 564 is used to combine the outputs of the directional couplers 562 to provide a composite calibration signal that is routed to the calibration port 532 of the antenna 500 . As shown in FIG. 8 , the calibration circuit board 550 includes eight conductive structures (shown as conductive pads) 552 (see FIG. 7 ) that may be located directly behind each opening 504 in the backplane 502 . As mentioned above, each conductive structure 552 forms part of a respective one of the directional couplers 562 of the calibration circuit 560 . Conductive traces 554 connect each conductive structure 552 associated with a particular feed plate 513 (the location of feed plate 513 is shown using a dashed box in FIG. 8 ) to a corresponding 2x1 combiner 566 . The outputs of the four 2x1 combiners 566 connected to the conductive structure are connected to the inputs of two additional 2x1 combiners 566, and the outputs of the two additional 2x1 combiners 566 are coupled to the inputs of the final 2x1 combiner 566 terminal to form a three-level tree structure of 2x1 combiners 566 acting as 8x1 calibration combiners 564. The output of the final 2x1 combiner 566 is coupled to a mount 568 that can accommodate a calibration cable 580 .

Accordingly, the base station antenna 500 includes a backplane 502 having a front surface and a rear surface, and a plurality of radiating elements 520 extending forwardly from the backplane 502 . A plurality of feed boards 512, 513 are mounted on the front of the backplane 502, wherein each feed board 512, 513 has a respective set of one or more radiating elements 520 mounted thereon. The antenna 500 also includes a calibration circuit 560 that includes a plurality of components 516 mounted on the front of the backplane 502 and at least one additional component 552 , 566 mounted on the back of the backplane 502 .

Calibration circuit design for base station antenna 500 may have many advantages. First, this arrangement allows the calibration circuit board 550 to be implemented on the backside of the backplane 502 , so the backplane 502 shields the calibration circuit 560 from the RF energy emitted by the radiating element 520 . Additionally, all calibration combiners 566 may be implemented on the same circuit board 550 , so base station antenna 500 may have fewer cable connections than, for example, base station antenna 400 .

FIG. 9 is a schematic cross-sectional view illustrating another technique for implementing the directional coupler 562 included in the base station antenna 500 of FIG. 6 . In particular, FIG. 9 is a thin cross-section taken through the feed board 513, backplane 502, and calibration circuit board 550 of FIG. An alternate implementation of one of the directional couplers 562 in the antenna 500 .

In practice, the feed boards and calibration circuit boards included in base station antennas are usually formed using microstrip printed circuit boards, and in some cases implemented using stripline or other circuit boards. As is known to those skilled in the art, a microstrip printed circuit board is typically implemented with a conductive ground plane formed on its first major surface (eg, bottom surface), and a conductive ground plane formed on an opposite major surface (eg, top surface). Conductive patterns are formed on the dielectric substrate. The conductive pattern may include one or more traces defining RF transmission lines, and may also include conductive pads or other conductive structures forming circuit elements, input/output ports, and the like. The ground plane is typically formed as a continuous or near-continuous sheet of metal that substantially or completely covers the bottom surface of the dielectric substrate. Figure 9 illustrates a practical implementation of the directional coupler 562 of the base station antenna 500 when the feed board 513 and the calibration circuit board 550 are formed as microstrip printed circuit boards.

Referring to the schematic cross-sectional view of FIG. 9, it can be seen that the calibration circuit board 550 can be positioned immediately adjacent to and behind the backplane 502, while the feed board 513 can be positioned immediately adjacent to and behind the backplane 502. Front. Feed board 513 is a microstrip feed board that includes a dielectric substrate 590 with a ground plane 592 formed on its backside, and traces for RF transmission lines 514 are formed on the front surface of dielectric substrate 517 . As shown in FIG. 9 , an opening 594 is provided in the ground plane 592 behind the trace of the RF transmission line 514 . Calibration circuit board 550 is also implemented as a microstrip feed board, calibration circuit board 550 includes a dielectric substrate 557 with a ground plane 558 formed on its front surface, and conductive structures 552 are formed on the rear surface of dielectric substrate 557 . As further shown in FIG. 9 , an opening 559 is provided in the ground plane 558 in front of the conductive structure 552 . The openings 594 , 559 in the respective ground planes 592 , 558 of the feed board 513 and the calibration circuit board 550 are aligned with each other and further with the aforementioned opening 504 in the backplane 502 . Thus, when an RF signal is transmitted on the feed board RF transmission line 514, a small portion of the RF energy will pass through the opening 594 in the ground plane 592 of the feed board 513, through the opening 504 in the backplane 502, through the calibration circuit board Opening 559 in ground plane 558 of 550 is coupled to RF transmission line 554 on calibration circuit board 550 including and/or connected to conductive structure 552 . Thus, FIG. 9 illustrates a practical implementation of one of the directional couplers 562 included in the calibration circuit 560 of the base station antenna 500 . It will be appreciated that the cross-section of FIG. 9 is "thin" in the sense that it is taken through a small portion of the antenna and corresponds to one of the openings 504 in the backplane 502, so the backplane 502, feeder Portions of electrical board 513 and calibration circuit board 550 outside the area of opening 504 are shown to more clearly illustrate opening 504 and openings 594 , 559 in corresponding feed board ground plane 592 and calibration circuit board ground plane 558 .

In the example of FIG. 9 , directional coupler 562 is formed through a single opening 504 in backplane 502 (and corresponding openings 594, 559 in ground planes 592, 558). However, it will be appreciated that in other embodiments two or more sets of openings may be provided to improve the directionality of the directional coupler 562 .

Fig. 10 is a schematic diagram illustrating a base station antenna 600 according to a further embodiment of the present invention. Base station antenna 600 is similar to base station antenna 400 described above, but has at least two basic differences. First, in the base station antenna 600 , the directional coupler of the calibration circuit 660 is implemented in the phase shifter 670 instead of on the feeder board 413 as in the base station antenna 400 . Second, in the base station antenna 600 the combiner portion of the calibration circuit is fully implemented on a single calibration circuit board 650 . The following discussion will focus on these two aspects in which base station antenna 600 differs from base station antenna 400 .

As shown in FIG. 10 , the base station antenna 600 may include four rows 610 of dual-polarized radiating elements 620 having a first radiator 622 and a second radiator 624 mounted on a backplane 602 . Radiating element 620 may be mounted on feed board 612 . In this embodiment, all feed plates 612 may be identical. Base station antenna 600 also includes eight RF ports 630 and a calibration port 632 . Input cables 640 connect each RF port 630 to a corresponding one of a plurality of electromechanical phase shifters 670 , and phase cables 676 connect the outputs of the phase shifters 670 to the feed board 612 . Backplane 602, feed board 612, radiating element 620, RF port 630, calibration port 632, input cable 640, and phase cable 676 can be compared to backplane 402, feed board 412, radiating element 420, RF port 430, The calibration port 432, input cable 440, and phase cable 476 are identical, so further description thereof will be omitted here. Base station antenna 600 also includes calibration circuitry 660, which will be described in more detail below. Calibration circuit 660 includes calibration circuit board 650 described above and eight directional couplers 662 formed as part of corresponding eight phase shifters 670 .

11 is a perspective view of a dual rotary wiper phase shifter assembly 700 that can be used to implement two electromechanical phase shifters 670 (one for each of the two polarizations) included in the base station antenna 600 . A total of four such phase shifter assemblies 700 are included in the base station antenna 600 , ie one assembly 700 per column of radiating elements 620 . As shown in FIG. 11 , the dual rotary wiper phase shifter assembly 700 includes a first phase shifter 670 and a second phase shifter 670 arranged in back-to-back relationship. Both phase shifters 670 may be identical, so only the front phase shifter 670 will be described here.

As shown in FIG. 11 , the front phase shifter 670 includes a main (stationary) printed circuit board 710 and a rotatable wiper printed circuit board 720 rotatably mounted on the main printed circuit board 710 by a pivot pin 722 . The position of the wiper printed circuit board 720 above the main printed circuit board 710 is determined by the position of a mechanical linkage 704 (partially shown in FIG. 11 ) extending between the output member of the RET actuator and the phase shifter 700. control. As the position of the mechanical linkage 704 changes, the wiper printed circuit board 720 rotates over the main printed circuit board 710 in order to change the relative phase of the sub-components of the RF signal output by the phase shifter 670 .

The main printed circuit board 710 includes transmission line traces 712 , 714 , 716 , 718 . The transmission line traces 712, 714 are generally arcuate. A first arcuate transmission line trace 712 is arranged along the outer circumference of the main printed circuit board 710 , and a second arcuate transmission line trace 714 is concentrically disposed on a shorter radius, within the outer transmission line trace 712 . Transmission line trace 716 connects input pad 730 on main printed circuit board 710 to the input of directional coupler 750 implemented on main printed circuit board 710 . A first output 752 of the directional coupler 750 is connected to a pad (not shown) on the main printed circuit board 710 . A second output 754 of the directional coupler 750 is connected to the transmission line trace 718 . Transmission line trace 718 extends between directional coupler 750 and one of a plurality of output pads 740 disposed along the edge of main printed circuit board 710 .

The center conductor of the input cable 640 (see FIG. 10 ) of the base station antenna 600 may be soldered to the input pad 730 (and the ground conductor of the input cable may be soldered to the ground plane of the main printed circuit board 710 ). The RF signal can be passed from one RF port 630 (see FIG. 10 ) of the base station antenna 600 to the input pad 730 through the input cable 640 . The RF signal will travel along transmission line trace 716 to directional coupler 750 . The directional coupler 750 can be configured to unevenly divide the RF energy input thereto such that most of the RF energy (e.g., about 80%) is delivered to the first output 752 and the remainder of the input RF energy is delivered to the second output 752. Output 754. The RF energy delivered to the first output 752 is then capacitively coupled to a transmission line trace (not visible in FIG. 11 ) on the wiper printed circuit board 720 . Another directional coupler (not shown) may be placed along the transmission line trace on the wiper printed circuit board 720, which splits the RF energy delivered to the wiper printed circuit board 720 into two sub-components. These two subcomponents of the RF signal are capacitively coupled from the output of the directional coupler on the wiper printed circuit board 720 to corresponding transmission line traces 712, 714 on the main printed circuit board. The subcomponent of the RF signal coupled to the transmission line trace 714 can be split into two subcomponents, where the first subcomponent travels to the left along the transmission line trace 714 (from the vantage point of FIG. 11 ), while the second subcomponent travels along the transmission line Trace 714 goes to the right. Similarly, a subcomponent of an RF signal coupled to transmission line trace 712 can likewise be split into two subcomponents, where the first subcomponent travels to the left along transmission line trace 712 and the second subcomponent travels along transmission line trace 712 to the right. Each end of each transmission line trace 712 , 714 may be coupled to a corresponding output pad 740 . Thus, phase shifter 670 splits the RF signal input at pad 730 into five components, which are passed to five corresponding output pads 740 .

As the wiper printed circuit board 720 moves, the distance from the input pad 730 of the phase shifter 670 to four of the five output pads 740 (i.e., the output pads 740 connected to the arced transmission line traces 712, 714) The electrical path length will change. For example, when the wiper printed circuit board 720 moves to the left, it shortens the electrical path length from the input pad 730 to the output pad 740 (which is connected to the first radiating element 620) connected to the left side of the transmission line trace 712, The electrical length from input pad 730 to output pad 740 (which is connected to second radiating element 620 ) connected to the right of transmission line trace 712 is increased by a corresponding amount. These changes in path length result in a phase shift of the signal received at output pad 740 connected to transmission line trace 712 relative to, for example, output pad 740 connected to transmission line trace 718 .

As shown in FIG. 11 , the rotary wiper PCB 720 of the rear phase shifter 670 may be controlled by the same mechanical linkage 704 as the rotary wiper PCB 720 of the top phase shifter 670 . This arrangement is typically used when the column 610 of radiating elements 620 is a column 610 of dual polarized radiating elements 620, since the same phase shift is typically applied to RF signals transmitted on each of the two orthogonal polarizations. Thus, a single mechanical linkage 704 can be used to control the position of the wiper printed circuit board 720 on both phase shifters 670 .

The main printed circuit 710 further includes a directional coupler 662 for tapping a small portion of the RF signal input at the input pad 730 . Directional coupler 662 may be implemented, for example, as a microstrip trace extending along transmission line trace 716 or as any other suitable directional coupler design. A portion of the RF signal passing along transmission line trace 716 may electromagnetically couple to the trace of directional coupler 662 and pass to calibration pad 780 . In an example embodiment, approximately 3-6% of the RF energy may be coupled to the traces of the directional coupler 662 . One end of an RF transmission line (not shown), such as, for example, one end of a coaxial cable, may be connected to the calibration pad 780 . The other end of the coaxial cable may be connected to a calibration printed circuit board 650 (see FIG. 10 ).

Referring again to FIG. 10, the calibration printed circuit board 650 includes a combiner circuit 664 that combines the RF energy tapped from each phase shifter 670 into a single composite RF signal. Combiner circuit 664 is shown schematically as a block in FIG. 10 . Combiner circuit 664 may include, for example, seven 2x1 power combiners that combine the eight tapped signals into a single composite calibration signal. For example, seven 2x1 combiners may be arranged in the same manner as combiner 366 discussed above with reference to FIG. 4 and may be implemented in the same manner (eg, as a Wilkinson power combiner). The output of the last 2x1 combiner in the tree structure can be electrically connected to the calibration port 632 through the calibration cable 680, as shown in FIG. 10 .

The calibration circuit 660 is similar to the calibration circuit 460 described above, with the main difference that the calibration signal is tapped from the phase shifter 670 instead of the feed board. This approach may be advantageous because the phase shifter 670 is located on the back of the reflector 602, while the feed plate 612 is usually located on the front of the reflector 602, so if the directional coupler 662 is implemented as part of the phase shifter 670, It is then easier to connect the directional coupler to the calibration printed circuit board 650 . Additionally, by moving the directional coupler 662 from the feed board 612 to the main printed circuit board 710 of the phase shifter 670, the possibility of radiation emitted by the radiating element 620 of the base station antenna 600 introducing noise into the calibration signal can be reduced.

FIG. 12 is a perspective view of a phase shifter assembly 700 ′ that is a modified version of the phase shifter assembly 700 of FIG. 11 . According to other embodiments of the present invention, a phase shifter assembly 700' may be used instead of the phase shifter assembly 700 in the base station antenna. It can be seen that phase shifter assembly 700 ′ can be identical to phase shifter 700 , except that directional coupler 662 ′ included in base station antenna 700 ′ is formed on transmission line trace 718 rather than on transmission line trace 716 . This arrangement may be advantageous because the addition of a directional coupler to the calibration circuit 660 increases the insertion loss along the RF path. By positioning directional coupler 662' after directional coupler 750, the effect of insertion loss can be reduced. As noted above, only about 20% of the RF energy input to phase shifter 670 is delivered to transmission line trace 718 in a typical embodiment. Directional coupler 662 ′ may then extract approximately 5% of the RF energy delivered to transmission line trace 718 , for example. Thus, since directional coupler 662' is positioned after directional coupler 750, the insertion loss of directional coupler 662' only degrades each RF signal by about 20%, effectively reducing insertion loss by about 80%. Directional couplers 662' may be formed along the output traces of each phase shifter 670 that are not subject to variable phase shifts (ie, transmission line traces 718).

Although Figures 11 and 12 illustrate implementing the calibration coupler on the main printed circuit board of a rotary wiper arc phase shifter, it should be appreciated that some portions of the calibration circuitry can be implemented on the printed circuit board of any conventional phase shifter. On-board implementation, conventional phase shifters include, for example, trombone-type sliding dielectric phase shifters, phase shifters comprising multiple rotating wiper printed circuit boards, and the like. It should therefore be appreciated that the rotary wiper arc phase shifters depicted in Figures 11 and 12 are provided only as examples of possible implementations of the concepts according to the invention on a phase shifter circuit board.

FIG. 13 is a schematic diagram of a base station antenna 800 including a modified version of the calibration circuit included in the base station antenna 500 of FIGS. 6-8 . The base station antenna 800 combines the features of the base station antenna 400 in FIG. 5 and the base station antenna 500 in FIGS. 6-8 . In particular, base station antenna 800 implements four combiners 866 of calibration combiners on feeder board 813, as in base station antenna 400 of FIG. , as in the base station antenna 500 of FIGS. 6-8 . This arrangement reduces the number of slots needed in reflector 802 and allows a smaller calibration circuit board 850 to be used.

As shown in FIG. 13 , the base station antenna 800 includes four columns 810 of dual polarized radiating elements 820 having a first radiator 822 and a second radiator 824 mounted on a backplane 802 . Radiating element 820 may be mounted on feeder boards 812 and 813 . Base station antenna 800 also includes eight RF ports 830 and a calibration port 832 . An input cable 840 connects each RF port 830 to a corresponding one of the plurality of phase shifters 870 , and a phase cable 876 connects the output of the phase shifter 870 to the feed boards 812 , 813 . Backplane 802, feed board 812, radiating element 820, RF port 830, calibration port 832, input cable 840, and phase cable 876 can be compared to backplane 402, feed board 412, radiating element 420, RF port 430, The calibration port 432, input cable 440, and phase cable 476 are identical, so further description thereof will be omitted here.

As further shown in FIG. 13 , the base station antenna 800 includes a calibration circuit board 850 mounted under four feeder boards 813 with a backplane 802 between them. The feed boards 813 may be similar to the feed boards 513 of the base station antenna 500, except that each feed board 813 may also include a combiner 866 thereon, the combiner 866 combining the signals from the two RF transmission lines 814, 815. The RF energy tapped by directional coupler 862 is combined. The output of each combiner 866 is electromagnetically coupled to a trace (or other structure) on the calibration circuit board 850 through a corresponding opening 806 in the backplane 802 . FIG. 14 is a schematic exploded perspective view of a portion of the base station antenna of FIG. 13 further illustrating the design and operation of the calibration circuit 860 included in the base station antenna 800 . In particular, FIG. 14 illustrates a portion of one of the feed boards 813 and portions of the reflector 802 and the calibration circuit board 850 behind the feed board 813 .

14, the feed board 813 includes a pair of feed points 882, and each feed point 882 receives the center conductor of a corresponding phase cable 876 (the outer conductor of each phase cable 876 can be welded to the feeder board 813 on the ground plane formed on the backside of the ). Each feed point 882 is connected to a respective RF transmission line 884 connecting the feed point 882 to a respective pad 886 . The radiating element 820 is mounted on the pad 886 such that the first feed point 886 is electrically connected to the first radiator 822 via the first RF transmission line 884 and the first pad 886, and the second feed point 886 is electrically connected to the first radiator 822 via the second RF transmission line. 884 and the second pad 886 are electrically connected to the second radiator 824 . The first and second directional couplers 862 are provided in the form of respective transmission line traces 863 extending parallel to the first and second RF transmission lines 884 from the respective first and second RF transmission lines 863. Two transmission lines 884 tap RF energy. A first end of each RF transmission line trace 863 is terminated to a resistor 888, and a second end of each RF transmission line 863 is coupled to an input of a power combiner 866 (eg, a Wilkinson power combiner). The output 868 of the power combiner 866 is routed over an opening 890 in the ground plane on the back of the feed board 813 . The backplane 802 has an opening 806 therein behind an opening 890 in the ground plane of the feed plate 813 . Calibration circuit board 850 is positioned behind backplane 802 . Calibration circuit board 850 may include conductive structures 852 such as, for example, conductive pads directly behind opening 806 in backplane 802 . RF energy present at output 868 of power combiner 866 may thus be electromagnetically coupled to conductive structure 852 through opening 806 in backplane 802 . The arrangement shown in FIG. 14 exists relative to each of the four feed boards 813 such that RF energy is coupled to four separate conductive structures 852 on the calibration circuit board 850 . First to third 2x1 directional couplers (not shown) may be provided on the calibration circuit board 850 . The four conductive structures 852 on the calibration circuit board 850 can be coupled to respective inputs of the first and second 2x1 directional couplers, and the outputs of the first and second 2x1 directional couplers can be coupled to a third 2x1 directional coupler to combine the four calibration signals that are electromagnetically coupled from the four respective feed boards 813 to the conductive structures 852 on the calibration circuit board 850 . The output of the third 2×1 directional coupler may be coupled to a fixture that receives a calibration cable 880 .

It should be appreciated that the directional coupler of the calibration circuit may also be located on other printed circuit boards included in the base station antenna. For example, some base station antennas include a duplexer that is used to combine RF signals traveling along a transmit path so that the combined signal can be transmitted through a so-called "broadband" radiating element, and the duplexer is used to separate the received RF signals in different frequency bands are received so that the received signals can be passed to the appropriate receivers. In some cases, these duplexers are implemented on printed circuit boards. In other embodiments of the present invention, the directional coupler of the calibration circuit may be implemented on the diplexer printed circuit board instead of the feeder printed circuit board or the phase shifter printed circuit board. The duplexer may be located at any conventional location along the RF path, including between the RF port and the phase shifter or between the phase shifter and the radiating element. The combiner circuit can be implemented on a separate calibration circuit board, partly on a diplexer printed circuit board and a calibration circuit board, or in a common implemented on a printed circuit board.

As another example, some base station antennas are designed with fixed downtilt (or no downtilt), rather than variable downtilt that can be adjusted using electromechanical phase shifters. These fixed-tilt antennas usually have a power splitter printed circuit board for splitting the RF signal to be transmitted into multiple sub-RF components. These power splitter printed circuit boards perform the power splitting function (as described above) performed by the electromechanical phase shifters included in the base station antennas according to various embodiments of the present invention, without implementing variable phase delays. It should be appreciated that directional couplers may also be included in such antennas in the same manner as directional couplers implemented on the main printed circuit board of the phase shifters in the base station antennas discussed above with reference to FIGS. 10-12. The power divider is implemented on a printed circuit board.

FIG. 15 is a schematic plan view of a portion of a base station antenna 900 including four phase shifters 910 mounted on a metal support plate 912 . FIG. 15 shows how a calibration coupler 940 may be formed, for example, on the main printed circuit board 920 of each phase shifter 910, the calibration coupler 940 electromagnetically extracts the calibration signals, and passes these extracted calibration signals to a circuit comprising a calibration combiner. The calibration circuit board 950 of the circuit.

As shown in FIG. 15 , each phase shifter 910 may include a main printed circuit board 920 and a wiper printed circuit board 930 . Each phase shifter 910 may be identical to one of the phase shifters 670 shown in FIG. 12 except for how the calibration coupler is implemented. As shown in FIG. 15, the main printed circuit board 920 of each phase shifter 910 includes an input RF transmission line 922 (which may be the same as the input RF transmission line 716 of the phase shifter 670 of FIG. 12) and an output RF transmission line 924 (which may be Same as output RF transmission line 718 of phase shifter 670 of FIG. 12). A calibration coupler 940 is implemented along the output RF transmission line 924 of each phase shifter 910 using electromagnetic coupling through openings in the metal plate in a manner similar to that shown in FIG. 14 . In particular, as shown in FIG. 15 , a calibration coupler 940 may be formed on each phase shifter 910 by forming an opening 942 in the ground plane of each main printed circuit board 920, for example below the corresponding output RF transmission line 924. . A calibration circuit board 950 may be installed under the phase shifter 910 and under the metal plate 912 . Corresponding openings are formed in the metal plate 912 below the corresponding openings 942 in the ground plane of the main printed circuit board 920 of the corresponding phase shifters 910 (not shown separately in FIG. opening 942). Conductive pads 944 may be formed on calibration circuit board 950 directly below corresponding openings 914 in metal plate 912 . RF energy delivered along each output transmission line 924 may be electromagnetically coupled to conductive pad 944 through a corresponding opening 942 in ground plane, through a corresponding opening in metal plate 912 . In other words, the combination of the opening 942 in the ground plane, the opening in the metal plate 912, and the conductive pad 944 can be used to implement a calibration coupler 940 that couples RF energy from the corresponding output transmission line 924 to the conductive pad 940. Electrical pad 944.

As further shown in FIG. 15, calibration circuit board 950 may include calibration combiners 952-1 through 952-3. Calibration combiner 952-1 may be coupled by RF transmission line 954 to first pair of conductive pads 944 to combine the calibration signals coupled to those pads 944, while calibration combiner 952-2 may similarly be coupled by RF transmission line 954 to the first pair of conductive pads 944. Two pairs of conductive pads 944 are used to combine the calibration signals coupled to those pads 944 . An additional RF transmission line 954 may be provided on the calibration circuit board 950 for coupling the outputs of the calibration combiners 952-1 and 952-2 to a third calibration combiner 952-3 which outputs a combined calibration signal. Thus, FIG. 15 illustrates how the electromagnetic coupling techniques discussed above with reference to, for example, FIGS. 7-9 and 13-14 can also be used to couple a base station antenna with calibration circuitry from a phase shifter printed circuit board.

In the example embodiment described above, each antenna includes four columns of dual polarized radiating elements, where each feed plate (except feed plate 313 which includes eight radiating elements) provides two radiating elements, for a total of six columns per column. a radiating element. However, it will be appreciated that other numbers of columns and/or radiating elements may be included in the antenna according to embodiments of the invention, and that the number of radiating elements per feed plate may vary (e.g., typically including one radiating element or three radiating elements), and different feeder boards may have different numbers of radiating elements. Accordingly, it will be appreciated that the above-described embodiments are exemplary in nature and are not intended to limit the scope of the invention, but simply illustrate that the calibration circuit may follow the electrical path connecting the phase shifter to the radiating element There are several different example ways in which antennas can be implemented to provide lower cost and/or improved performance.

The present invention has been described above with reference to the accompanying drawings. The invention is not limited to the illustrated embodiments; rather, these embodiments are intended to fully and completely disclose the invention to those skilled in the art. In the drawings, like numerals refer to like elements throughout. Thicknesses and dimensions of some elements may not be to scale.

For ease of description, spatially relative terms may be used herein, such as "under", "beneath", "below", "above", "on", "top" , "bottom", etc., to describe the relationship between one element or feature and one or more other elements or features, as shown in the figure. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Well-known functions or constructions may not be described in detail for brevity and/or clarity. As used herein, the expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be appreciated that features exemplified with one of the above example embodiments may be incorporated into any other example embodiment. Accordingly, it will be appreciated that the disclosed embodiments may be combined in any manner to provide many additional embodiments.

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.

Claims (23)

1. A base station antenna, comprising: Backplane; a plurality of radiating elements, the plurality of radiating elements including at least a first radiating element and a second radiating element, each radiating element extending forwardly from the backplate; a plurality of feed boards comprising at least a first feed board and a second feed board, wherein each feed board has a respective set of one or more radiating elements mounted thereon; Calibration port; and A calibration circuit, the calibration circuit comprising: a calibration combiner having an output coupled to the calibration port; and a plurality of directional couplers, the plurality of directional couplers comprising at least a first directional coupler and a second directional coupler coupled to the calibration combination device, wherein at least a first portion of said first directional coupler is implemented on said first feeder board, Wherein the first radiating element is mounted on the first feed plate and includes a dual-polarized radiating element, the dual-polarized radiating element includes a first radiator radiating with a first polarization and a second radiator of second polarized radiation, and wherein the first directional coupler is coupled to the first radiator and the second directional coupler is coupled to the second radiator, Wherein the first directional coupler and the second directional coupler are fully implemented on the first feed board, and the first feed board further includes a a combiner of the tap port and the tap port of the second directional coupler, wherein the combiner comprises a portion of the calibration combiner, and Wherein another part of the calibration combiner is located on a calibration circuit board separate from the first feed board. 2. The base station antenna of claim 1 , wherein the first radiating element is in a first column of the plurality of columns, and the second radiating element is in the same column as the second of the plurality of columns. in a second horizontally spaced column, and wherein the first directional coupler is configured to couple radio frequency energy from a transmission line connected to the first radiating element, and the second directional coupler is configured to for coupling radio frequency energy from a transmission line connected to said second radiating element. 3. A base station antenna, comprising: Backplane; a plurality of radiating elements, the plurality of radiating elements including at least a first radiating element and a second radiating element, each radiating element extending forwardly from the backplate; a plurality of feed boards comprising at least a first feed board and a second feed board, wherein each feed board has a respective set of one or more radiating elements mounted thereon; Calibration port; and A calibration circuit, the calibration circuit comprising: a calibration combiner having an output coupled to the calibration port; and a plurality of directional couplers, the plurality of directional couplers comprising at least a first directional coupler and a second directional coupler coupled to the calibration combination device, wherein at least a first portion of said first directional coupler is implemented on said first feeder board, a first radio frequency port; and a first electromechanical phase shifter coupled between the first radio frequency port and the first radiating element, wherein the first directional coupler is configured to couple radio frequency energy from a first transmission path extending from the first output of the first electromechanical phase shifter to the first radiating element, Wherein the radiating elements are arranged in a plurality of columns. 4. The base station antenna of claim 3, wherein said first output of said first electromechanical phase shifter comprises an output that is not subject to an adjustable phase shift. 5. A base station antenna, comprising: Backplane; a first plurality of radiating elements arranged to define a first column of radiating elements; a second plurality of radiating elements arranged to define a second column of radiating elements; a first radio frequency port; the second radio frequency port; a first electromechanical phase shifter electrically coupled between the first radio frequency port and the first column of radiating elements; a second electromechanical phase shifter electrically coupled between the second radio frequency port and the second column of radiating elements; and A calibration circuit, the calibration circuit comprising: a first directional coupler coupled along between the input of the first electromechanical phase shifter and a first one of the radiating elements in the first column of radiating elements A first radio frequency transmission path coupling extending between; and a second directional coupler extending along between the input of the second electromechanical phase shifter and a first one of the radiating elements in the second column of radiating elements The second RF transmission path coupling, wherein the calibration circuit further includes a combiner configured to combine radio frequency energy present at the tap port of the first directional coupler with a tap port of the second directional coupler Combining radio frequency energy on , wherein the output of the combiner is coupled to the calibration port of the base station antenna, wherein said first of the radiating elements in said first column of radiating elements is mounted to extend forwardly from a first feed plate and said ones of radiating elements in said second column of radiating elements A first radiating element is mounted to extend forwardly from a second feeder plate, and wherein a first directional coupler is at least partially implemented on said first feeder plate, and said second directional coupler is at least partially implemented on said first feeder plate Realized on the second feeder board. 6. The base station antenna of claim 5, wherein said first of the radiating elements in said first column of radiating elements is a dual polarized radiating element comprising a A first radiator of the first radio frequency transmission path and radiating with a first polarization and a second radiator coupled to the third radio frequency transmission path and of radiating with a second polarization different from said first polarization. 7. The base station antenna of claim 5, wherein the combiner is implemented on a calibration circuit board. 8. The base station antenna as claimed in claim 5, wherein said first feed board and said second feed board are mounted on the front of said back board, and said calibration circuit board is mounted on the front of said back board later. 9. The base station antenna of claim 5, wherein said first of the radiating elements in said first column of radiating elements is mounted to extend forwardly from a first feed plate, and wherein said The first directional coupler comprises a first part being part of said first feed board and a second part being part of a calibration circuit board. 10. The base station antenna of claim 9, wherein the first feed board is on a first side of the backplane, and the calibration circuit board is on an opposite side of the backplane to the first side second side. 11. A base station antenna, comprising: Backplane; a first plurality of radiating elements arranged to define a first column of radiating elements; a second plurality of radiating elements arranged to define a second column of radiating elements; a plurality of feed boards, wherein each feed board has a respective set of one or more radiating elements mounted thereon; a first radio frequency port; the second radio frequency port; a first electromechanical phase shifter electrically coupled between the first radio frequency port and the first column of radiating elements; a second electromechanical phase shifter electrically coupled between the second radio frequency port and the second column of radiating elements; and A calibration circuit, the calibration circuit comprising: a first directional coupler coupled along between the input of the first electromechanical phase shifter and a first one of the radiating elements in the first column of radiating elements A first radio frequency transmission path coupling extending between; and a second directional coupler extending along between the input of the second electromechanical phase shifter and a first one of the radiating elements in the second column of radiating elements The second RF transmission path coupling, The first directional coupler is implemented on a printed circuit board of the first electromechanical phase shifter. 12. The base station antenna of claim 11 , wherein said first directional coupler is implemented along an input radio frequency transmission line on a printed circuit board of said first electromechanical phase shifter, said input radio frequency transmission line connecting said The input port of the first electromechanical phase shifter is connected to a power divider included on the printed circuit board of the first electromechanical phase shifter. 13. The base station antenna as claimed in claim 11 , wherein said first directional coupler is implemented along a radio frequency transmission line, said radio frequency transmission line is connected to a power divider on a printed circuit board of said first electromechanical phase shifter extending between the output ports of the first electromechanical phase shifter. 14. The base station antenna of claim 13, wherein the radio frequency transmission line extending between the power splitters on the printed circuit board of the first electromechanical phase shifter has a fixed length. 15. A base station antenna, comprising: Backplane; a first plurality of radiating elements arranged to define a first column of radiating elements; a second plurality of radiating elements arranged to define a second column of radiating elements; a plurality of feed boards, wherein each feed board has a respective set of one or more radiating elements mounted thereon; a first radio frequency port; the second radio frequency port; a first electromechanical phase shifter electrically coupled between the first radio frequency port and the first column of radiating elements; a second electromechanical phase shifter electrically coupled between the second radio frequency port and the second column of radiating elements; and A calibration circuit, the calibration circuit comprising: a first directional coupler coupled along between the input of the first electromechanical phase shifter and a first one of the radiating elements in the first column of radiating elements A first radio frequency transmission path coupling extending between; and a second directional coupler extending along between the input of the second electromechanical phase shifter and a first one of the radiating elements in the second column of radiating elements The second radio frequency transmission path coupling; and A duplexer printed circuit board, the duplexer printed circuit board including at least one duplexer, wherein the first directional coupler is implemented on the duplexer printed circuit board. 16. A base station antenna, comprising: a backplane having a front surface and a rear surface; a plurality of radiating elements extending forward from the backplane; a plurality of feed boards mounted on the front of the backplane, each feed board having a respective set of one or more radiating elements of the plurality of radiating elements mounted on the feed board; a calibration circuit comprising a plurality of components mounted on the front of the backplane and at least one additional component mounted on the back of the backplane, Wherein the plurality of components includes first portions of a corresponding plurality of directional couplers. 17. The base station antenna of claim 16, wherein the at least one additional component comprises at least a portion of a calibration combiner. 18. The base station antenna of claim 16, wherein the plurality of components comprises a plurality of directional couplers. 19. The base station antenna of claim 18, wherein the plurality of components further comprises a plurality of 2x1 combiners. 20. The base station antenna of claim 16, wherein the calibration circuit is mounted on a calibration circuit board, and wherein the second portion of each of the directional couplers is implemented on the calibration circuit board . 21. The base station antenna of claim 16, wherein the backplane includes an opening, and wherein the calibration circuit includes a directional coupler configured to electromagnetically couple radio frequency energy through the opening. 22. A base station antenna, comprising: Backplane; a plurality of radio frequency ports including at least a first radio frequency port and a second radio frequency port; a plurality of radiating elements, the plurality of radiating elements including at least a first radiating element and a second radiating element, each of the radiating elements extending forwardly from the backplate; a plurality of power dividers, including at least a first power divider and a second power divider, the first power divider is coupled between the first radio frequency port and the first radiating element, and the first two power splitters coupled between the second radio frequency port and the second radiating element; Calibration port; and A calibration circuit, the calibration circuit comprising: a calibration combiner having an output coupled to the calibration port; and a plurality of directional couplers, the plurality of directional couplers comprising at least a first directional coupler and a second directional coupler coupled to the calibration combination device, wherein said first directional coupler is implemented on a printed circuit board of said first power divider, wherein said second directional coupler is implemented on a printed circuit board of said second power divider, wherein said first power divider is part of a first phase shifter and said second power divider is part of a second phase shifter, Wherein the first phase shifter includes an input radio frequency transmission line, the first power divider and a plurality of output radio frequency transmission lines, and wherein the first directional coupler is implemented along the input radio frequency transmission line. 23. A base station antenna, comprising: Backplane; a plurality of radio frequency ports including at least a first radio frequency port and a second radio frequency port; a plurality of radiating elements, the plurality of radiating elements including at least a first radiating element and a second radiating element, each of the radiating elements extending forwardly from the backplate; a plurality of power dividers, including at least a first power divider and a second power divider, the first power divider is coupled between the first radio frequency port and the first radiating element, and the first two power splitters coupled between the second radio frequency port and the second radiating element; Calibration port; and A calibration circuit, the calibration circuit comprising: a calibration combiner having an output coupled to the calibration port; and a plurality of directional couplers, the plurality of directional couplers comprising at least a first directional coupler and a second directional coupler coupled to the calibration combination device, wherein said first directional coupler is implemented on a printed circuit board of said first power divider, wherein said second directional coupler is implemented on a printed circuit board of said second power splitter, wherein the first power divider is part of a first phase shifter and the second power divider is part of a second phase shifter, and wherein the first phase shifter includes an input radio frequency transmission line, the first power divider and a plurality of output radio frequency transmission lines, and wherein the first directional coupler is along one of the output radio frequency transmission lines It is achieved that said one output radio frequency transmission line has a fixed length that is not affected by variable phase shift.

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