Low-cost metal cavity phase shifter assembly with detachable front cover and metal shell

Abstract

A cavity phase shifter includes: a metal housing extending along a longitudinal axis, the metal housing having a first sidewall and a second sidewall connected by a first rear wall to define a first cavity having an open front; and a metal cover positioned in front of the open front portion of the first cavity.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to communication systems, and in particular to base station antennas for cellular communication systems. BACKGROUND

[0002] Cellular communication systems are well known in the art. In a cellular communication system, a geographical area is divided into a series of areas called "cells" which are served by a corresponding base station. Each base station can comprise one or more base station antennas configured to provide bi-directional radio frequency ("RF") communication with mobile users within the cell served by the base station. Typically, the base station antennas are mounted on a tower, with a radiation pattern (also referred to herein as an "antenna beam") generated by the outwardly pointing base station antenna.

[0003] A common base station configuration is a three-sector configuration, in which a cell is divided into three 120° sectors in the azimuth (horizontal) plane. A separate base station antenna provides coverage (service) for each sector. Typically, each base station antenna will comprise a plurality of vertically extending columns of radiating elements, for example operating using second generation ("2G"), third generation ("3G") or fourth generation ("4G") cellular network protocols. These vertically extending columns of radiating elements are commonly referred to as "linear arrays", and the radiating elements in a linear array are all coupled to the same feed network so that each radiating element will transmit a sub-component of the same RF signal. It will be appreciated that these vertically extending columns of radiating elements can be straight columns, or can be columns in which some of the radiating elements are horizontally staggered or have two radiating elements horizontally aligned, as a way of narrowing the beam width of the antenna beam generated in the azimuth (horizontal) plane. In this document, the term "linear array" is used broadly to encompass all of the above configurations. Most modern base station antennas comprise "low-band" linear arrays of radiating elements supporting service in some or all of the 617-960 MHz frequency band, and "mid-band" linear arrays of radiating elements supporting service in some or all of the 1427-2690 MHz frequency band. These linear arrays are typically formed using dual-polarized radiating elements, which allow each linear array to be connected to a pair of radio ports so that the linear array can transmit and receive RF signals simultaneously at two orthogonal polarizations (i.e. generate an antenna beam at each orthogonal polarization).

[0004] An RF signal, transmitted by one of the linear arrays described above, is generated in a wireless device and output via a radio port connected to the base station antenna (e.g., by a coaxial cable). The base station antenna divides the RF signal into multiple sub-components, and each sub-component is fed to a corresponding subset of radiating elements in the linear array (e.g., one to three radiating elements). The sub-components of the RF signal are transmitted through the radiating elements in their respective subsets to generate coverage of a substantially fixed area (e.g., 120 km of a cell). 0 The antenna beam of a sector. Typically, these linear arrays will have remote electronic tilt (“RET”) capability, which allows cellular operators to electronically change the pointing angle (called “downtilt”) of the generated antenna beam in the elevation (vertical) plane to change the size of the sector served by the linear array. Because the antenna beam generated by the above-mentioned 2G / 3G / 4G linear arrays is a static antenna beam whose shape changes only due to the adjustment of the antenna beam’s downtilt angle, the above-mentioned linear arrays are often referred to as “passive” linear arrays.

[0005] Cellular operators are currently upgrading their networks to support fifth-generation (“5G”) cellular services. A key component of 5G cellular services is the use of multiple rows of “active” beamforming arrays that work in conjunction with beamforming radios. The beamforming radios set the amplitude and / or phase of sub-components of the RF signal to be transmitted, such that the sub-components constructively combine in certain directions when transmitted by the radiating elements of the beamforming array. The beamforming radios can transmit different RF signals in time slots of a time-division multiple access scheme, resulting in different antenna beams generated in different sets of time slots. By setting the amplitude and phase of each different RF signal sub-component, the active beamforming array generates antenna beams with different sizes, shapes, and / or directional orientations on a slot-by-slot basis. These active beamforming arrays typically use “high-frequency band” radiating elements operating in higher frequency bands (e.g., some or all of the 3.3–4.2 GHz and / or 5.1–5.8 GHz bands), but active beamforming radios operating in other bands, such as the higher portion of the mid-frequency range (e.g., 2.5–2.7 GHz), are also possible. The radiating elements in each vertically extending column of such an active beamforming array are typically coupled to a corresponding port of the beamforming radio, such that each column of radiating elements is fed different sub-components of the signal to be transmitted. The beamforming radio can be a standalone device or can be integrated with an active antenna array. These active beamforming arrays can generate antenna beams with a narrowed beamwidth in the azimuth plane (and thus higher antenna gain). These narrowed antenna beams can be electronically redirected throughout the sector by appropriately selecting the amplitude and phase of each different sub-component of the RF signal. To avoid having to increase the number of antennas at cell sites, 5G antennas, including this beamforming array, typically also include passive linear arrays that support traditional 2G, 3G, and / or 4G cellular services. Summary of the Invention

[0006] According to an embodiment of the present invention, a cavity phase shifter assembly is provided, comprising: a metal housing extending along a longitudinal axis, the metal housing having a first sidewall and a second sidewall connected by a rear wall to define a first cavity having an open front portion; and a metal cover positioned in front of the open front portion of the first cavity.

[0007] In some embodiments, the metal cover includes a plurality of openings providing access to the first cavity.

[0008] In some embodiments, the metal housing further includes a first lip extending away from the first cavity and a second lip extending away from the first cavity. In some embodiments, the first lip extends parallel to the main surface of the metal cover, and the second lip also extends parallel to the main surface of the metal cover.

[0009] In some embodiments, the cavity phase shifter assembly further includes a dielectric material disposed between the metal housing and the metal cover. In some cases, the dielectric material may be a gasket.

[0010] In some embodiments, the metal housing may further include a third sidewall and a fourth sidewall connected by a second rear wall to define a second cavity having an open front portion. The metal cover may also be positioned in front of the open front portion of the second cavity.

[0011] In some embodiments, multiple connectors attach the metal housing to the metal cover.

[0012] In some embodiments, the metal housing comprises a metal plate. In other embodiments, the metal housing comprises metallized plastic. In some embodiments, the metal cover comprises a metal plate. In some embodiments, the metal cover comprises a reflector for a base station antenna.

[0013] In some embodiments, the cavity phase shifter assembly further includes a phase shifter printed circuit board in the first cavity, wherein the phase shifter printed circuit board includes a forward-extending tab extending through a first opening in an opening in the metal cover. In some embodiments, the rear edge of the phase shifter printed circuit board contacts the rear wall of the metal housing.

[0014] According to other embodiments of the present invention, a cavity phase shifter assembly is provided, comprising: a metal housing including a first cavity having an open front portion and a second cavity having an open front portion; a first phase shifter assembly in the first cavity; a second phase shifter assembly in the second cavity; and a metal cover positioned in front of the open front portions of the first cavity and the second cavity.

[0015] In some embodiments, the metal cap includes a plurality of openings that provide access to the first cavity and the second cavity.

[0016] In some embodiments, the metal housing includes: a first sidewall and a second sidewall connected by a first rear wall to define a first cavity; and a third sidewall and a fourth sidewall connected by a second rear wall to define a second cavity. In some embodiments, the metal housing further includes a first lip extending away from the first cavity and a second lip extending away from the first cavity and toward the second cavity. In some embodiments, the first lip extends parallel to the main surface of the metal cap, and the second lip also extends parallel to the main surface of the metal cap.

[0017] In some embodiments, the cavity phase shifter assembly further includes a separator disposed between the metal housing and the metal cover. The separator may include, for example, a resilient conductive separator or a dielectric separator.

[0018] In some embodiments, multiple connectors attach the metal housing to the metal cover.

[0019] In some embodiments, the metal housing comprises a metal plate. In other embodiments, the metal housing comprises metallized plastic. In some embodiments, the metal cover comprises a metal plate.

[0020] In some embodiments, the metal cover includes part of a reflector for a base station antenna.

[0021] In some embodiments, the cavity phase shifter assembly further includes a first phase shifter printed circuit board in the first cavity and a second phase shifter printed circuit board in the second cavity, wherein the first phase shifter printed circuit board includes a forward-extending tab extending through a first opening in an opening in the metal cover.

[0022] According to another embodiment of the invention, a cavity phase shifter assembly is provided, comprising: a metal housing extending along a first longitudinal axis; and a metal cover. The metal housing includes: a first sidewall; a second sidewall; a rear wall connecting the first sidewall to the second sidewall; a first lip extending outwardly from a front edge of the first sidewall; and a second lip extending outwardly from a front edge of the second sidewall. The metal cover extends parallel to the first and second lips.

[0023] In some embodiments, the first sidewall, the second sidewall, and the rear wall define a first cavity with an open front portion, and the metal cap is positioned in front of the open front portion of the first cavity. In some embodiments, the metal cap includes a plurality of openings that provide access to the first and second cavities.

[0024] In some embodiments, the first lip extends parallel to the main surface of the metal cap, and the second lip also extends parallel to the main surface of the metal cap.

[0025] In some embodiments, the cavity phase shifter assembly further includes a spacer disposed between the metal housing and the metal cap. In some embodiments, the spacer includes a conductive spacer. In some embodiments, the spacer includes a dielectric material, and the metal cap is capacitively coupled to the metal housing.

[0026] In some embodiments, multiple connectors attach the metal housing to the metal cover.

[0027] In some embodiments, the metal housing comprises a metal plate. In other embodiments, the metal housing comprises metallized plastic.

[0028] In some embodiments, the metal cover comprises a metal plate.

[0029] In some embodiments, the metal cover includes part of a reflector for a base station antenna. Attached Figure Description

[0030] FIG. 1A It is a front perspective view of a base station antenna that includes both passive linear arrays and active beamforming arrays.

[0031] FIG. 1B The radome has been removed. FIG. 1A A schematic front view of the base station antenna.

[0032] FIG. 1C It can be used for implementation FIGS. 1A-1B A schematic side perspective view of a representative portion of a conventional low-frequency band linear array assembly included in a base station antenna.

[0033] FIG. 1D yes FIG. 1C An end view of the cavity phase shifter assembly included in the low-frequency band linear array assembly.

[0034] FIG. 1E It shows FIG. 1D The cavity phase shifter assembly includes one of the phase shifter printed circuit boards.

[0035] FIG. 2A This is a schematic perspective view of a reflector used for a base station antenna that includes multiple metal housings integrated with the reflector.

[0036] FIG. 2B This is a schematic perspective view showing how a metal housing for a multi-cavity phase shifter assembly can be mounted on a frame.

[0037] FIG. 3A This is a schematic end view of a cavity phase shifter assembly according to an embodiment of the present invention.

[0038] FIG. 3B yes FIG. 3A A schematic front perspective view of one of the metal housings shown.

[0039] FIG. 3C yes FIG. 3A A schematic front perspective view of the metal cover shown.

[0040] FIG. 3D It is inside the box marked 3D. FIG. 3A A magnified view of the part.

[0041] FIG. 3E This is an end view of an intermediate frequency band linear array assembly according to an embodiment of the present invention, the intermediate frequency band linear array assembly including... FIG. 3A A linear array of cavity phase shifter components and mid-frequency radiating elements.

[0042] FIG. 3F It shows FIG. 3C A schematic perspective view of how a metal cover can serve as a larger reflector section for a base station antenna.

[0043] FIG. 4 This is a schematic end view of a metal housing for a cavity phase shifter assembly according to another embodiment of the present invention.

[0044] It should be noted that, in this document, the same element may be referenced individually by all of its reference numerals, and may also be referenced jointly by the first part of its reference numerals. Detailed Implementation

[0045] FIG. 1A and FIG. 1B A base station antenna 100 is shown, comprising both a passive low-frequency and mid-frequency linear array and a high-frequency active beamforming array. Specifically, FIG. 1A This is a front perspective view of the base station antenna 100, and FIG. 1B This is a schematic front view of the base station antenna 100 with the radome removed. FIG. 1A and 1B In the diagram, the axes show the vertical (V) direction, horizontal (H) direction, and forward (F) direction of the base station antenna system 100.

[0046] refer to FIG. 1AThe base station antenna 100 includes an radome 102, a top cover 104, and a bottom cover 106. A plurality of RF ports 108, in the form of RF connectors, are mounted in the bottom cover 106. The RF ports 108 extend through the bottom cover 106 and are used to electrically connect the base station antenna 100 to an external wireless device (not shown). The radome 102, top cover 104, and bottom cover 106 may form the outer housing of the antenna 100. Antenna assembly ( FIG. 1B It is contained within the shell.

[0047] FIG. 1B This is a schematic front view of the antenna assembly housed within the casing of the base station antenna 100. (Example) FIG. 1B As shown, the antenna assembly includes a reflector 110. The reflector 110 can serve both as a structural component of the antenna assembly and as a ground plane and reflector for at least some of the radiating elements (discussed below) of the antenna 100. The reflector 110 includes a generally flat metallic surface extending in the longitudinal direction L of the antenna 100. Various components of the base station antenna 100 (not shown) are mounted behind the reflector 110.

[0048] The antenna assembly also includes a first low-frequency band array and a second low-frequency band array 122-1, 122-2 of low-frequency band radiating elements 124; a first intermediate frequency band array and a second intermediate frequency band array 132-1, 132-2 of a first intermediate frequency band radiating element 134A; a third intermediate frequency band array 132-3 to a sixth intermediate frequency band array 132-6 of a second intermediate frequency band radiating element 134B; and a multi-column high-frequency band array 142 of a high-frequency band radiating element 144. The low-frequency band array 122 and the intermediate frequency band array 132 are each implemented as vertically extending passive linear arrays, generating coverage towards a predefined area (e.g., 120° of a base station). 0 A sector provides a static antenna beam for coverage, where only the coverage area changes when the electronic downtilt angle of the generated antenna beam is adjusted. High-frequency band radiating elements 144 are mounted in four columns in the lower central portion of the reflector 110 to form a multi-column high-frequency band array 142. Each column of the high-frequency band array 142 can be coupled to a pair of ports (one port per polarization) of a beamforming radio, such that the multi-column array 142 operates as an active beamforming array that generates a narrowed antenna beam that can be steered in the azimuth plane throughout the coverage area.

[0049] Low-frequency radiating element 124 is configured to transmit and receive signals in a frequency range of 617-960 MHz or a portion thereof. First intermediate-frequency (IF) radiating element and second IF radiating elements 134A, 134B are configured to transmit and receive signals in a frequency range of 1427-2690 MHz or a portion thereof, wherein the first IF radiating element and the second IF radiating elements 134A, 134B may have different designs and different operating frequency ranges (e.g., the first IF radiating element 134A operates in the entire 1427-2690 MHz frequency range, while the second IF radiating element 134B operates only in the 1695-2690 MHz frequency range). High-frequency radiating element 144 is configured to transmit and receive signals in a frequency range of 3300-4200 MHz or a portion thereof. Radiating elements 124, 134A, 134B, and 144 are mounted to extend forward from reflector 110. Radiation elements 124, 134A, 134B, and 144 can each be implemented as a dual-polarized radiation element, wherein the dual-polarized radiation element includes a first radiator and a second radiator (e.g., tilted -45°) that transmit and receive RF energy in orthogonal polarization. 0 / +45 0 Crossed dipole radiating element).

[0050] Each of the low-frequency band linear arrays 122 and 132 and the mid-frequency band linear arrays 122 and 132 can be connected to a pair of RF ports 108, which are used to connect each linear array 122 and 132 to a corresponding pair of radio ports. A first feed network connects the first RF port 108 of each pair of RF ports 108 to a first polarized radiator of the radiating element in the corresponding linear array of the linear arrays 122 and 132, and a second feed network connects the second RF port 108 of each pair to a second polarized radiator of the radiating element in the corresponding linear array of the linear arrays 122 and 132. Therefore, each linear array 122 and 132 can be used to generate a corresponding antenna beam at each polarization in the two polarizations. Each feed network may include a phase shifter 240 for each polarization (see...). FIGS. 1C-1E The phase shifter includes a power divider that splits the RF signal received from the radio device into multiple sub-components, which are fed to a corresponding first or second radiator of the radiating elements 124, 134A, 134B in the linear arrays 122, 132. Each phase shifter 240 can be used to apply a phase taper to the sub-components of the RF signal such that the resulting antenna beam will have a desired electrical downtilt. Each column of the high-frequency band radiating elements 144 is coupled to a pair of ports (each polarized) of the beamforming radio device (not shown).

[0051] like FIG. 1BAs shown in the diagram, the low-frequency radiating element 124 can be mounted on the low-frequency feed board printed circuit board 126, the intermediate-frequency radiating elements 134A and 134B can be mounted on the intermediate-frequency feed board printed circuit board 136, and the high-frequency radiating element 144 can be mounted on the high-frequency feed board printed circuit board 146. The feed board printed circuit boards 126, 136, and 146 couple RF signals between the radiating elements 124, 134A, 134B, and 144 mounted thereon and the phase shifter 240 discussed above. Cables (not shown) can be used to connect each feed board 126, 136, and 146 to the phase shifter 240.

[0052] A linear array and its associated feed network can be considered as including linear array components. Therefore, the base station antenna 100 includes, for example, two low-frequency band linear array components and six mid-frequency band linear array components. The linear array components are... FIG. 1B Unnumbered because FIG. 1B Only linear arrays 122 and 132 are visible because the feed network for the linear array components is primarily located behind reflector 110. However, as described below... FIG. 1C A portion of a linear array assembly 120 of a low-frequency band linear array assembly that can be used to implement a base station antenna 100 is shown.

[0053] The linear array assembly according to embodiments of the present invention is implemented using a cavity phase shifter assembly. Cavity phase shifter assemblies are known in the art. For example, U.S. Patent No. 11,677,141 discloses various cavity phase shifter assemblies and discusses their operation. The entire contents of U.S. Patent No. 11,677,141 are incorporated herein by reference. Cavity phase shifter assemblies may have certain advantages over non-cavity phase shifter assemblies because they include shielded stripline RF transmission lines and because they can be designed to provide cableless connections to radiating elements, which reduces the number of solder joints and the weight of coaxial phase cables.

[0054] FIG. 1C This is a schematic side perspective view of a representative portion of the linear array assembly 120 that can be used in a base station antenna 100. The linear array assembly 120 includes a linear array 122 and a cavity phase shifter assembly 200. FIG. 1C The low-frequency radiating element 124 and the feed plate 126 fed by the cavity phase shifter assembly 200 are also shown. FIG. 1D yes FIG. 1C End view of cavity phase shifter assembly 200. FIG. 1E yes FIGS. 1C-1D A schematic perspective view of one of the phase shifter printed circuit boards 242 included in the cavity phase shifter assembly 200.

[0055] First refer to FIG. 1C and 1DThe cavity phase shifter assembly 200 includes a metal housing 210 comprising a pair of outer sidewalls 212-1, 212-2, a (shared) inner sidewall 212-3, a rear wall 214, and a front wall 216, which together define a first longitudinally extending cavity and second longitudinally extending cavities 220-1, 220-2. The cavity phase shifter assembly 200 includes a first phase shifter and a second phase shifter 240-1, 240-2 mounted in the respective first and second cavities 220-1, 220-2. Each phase shifter 240 may, for example, be implemented as a sliding dielectric phase shifter including a phase shifter printed circuit board 242 and a sliding dielectric block 248. This allows the cavity phase shifter assembly 200 to feed the dual-polarized low-frequency band linear array 120 (i.e., to provide a feed network for each polarization).

[0056] The cavity phase shifter assembly 200 is mounted behind the reflector 110 of the base station antenna 100. A thin dielectric layer may be placed between the reflector 110 and the cavity phase shifter assembly 200, causing them to be capacitively coupled to each other, thereby grounding the metal housing 210 of the cavity phase shifter assembly 200. Since the phase shifter printed circuit board 242 is mounted in the grounded metal housing 210, the RF transmission lines on the phase shifter printed circuit board 242 operate as stripline transmission lines, which reduces RF loss and shields the RF transmission lines from external RF sources.

[0057] FIG. 1E It shows FIG. 1D One of the phase shifter printed circuit boards 242. For example... FIG. 1E As shown, each phase shifter printed circuit board 242 may include an input port 243 for receiving RF signals output from an associated radio device. The input port 243 is connected to a metal trace that allows the received RF signal to pass through a plurality of T-junctions 244, which together act as a power divider to split the RF signal received at the input port 243 into multiple sub-components. Each phase shifter printed circuit board 242 also includes a plurality of output RF transmission lines 245, wherein phase-adjusted sub-components of the RF signal are output from the phase shifter printed circuit board 242. FIG. 1E As shown, each output RF transmission line 245 extends to a corresponding tab in a plurality of forward-extending tabs 246. FIG. 1D As shown, each phase shifter assembly 240 also includes a sliding dielectric 248 mounted adjacent to the phase shifter printed circuit board 242. The sliding dielectric 248 is configured to impart an adjustable phase taper to the sub-components of the RF signal before they reach the corresponding output RF transmission line 245.

[0058] Refer again FIGS. 1C-1DAn opening 218 is disposed in the front wall 216 of the metal housing 210, and an opening 112 is disposed in the reflector 110. The aforementioned forward-extending tab 246 on each phase shifter printed circuit board 242 extends through the opening 218 in the front wall 216 of the metal housing 210, through the aligned opening 112 in the reflector 110, and into the opening in the corresponding low-band feed board 126. Solder joints can be applied to physically and electrically connect each output RF transmission line 245 to the corresponding RF transmission line on the low-band feed board printed circuit board 126. Each low-band feed board 126 may include a pair of power dividers that divide the RF signal provided thereto via the output RF transmission line 245 of the phase shifter printed circuit board 242 and transmit sub-components of the divided RF signal to the appropriate radiator of the low-band radiating element 124. This eliminates the need for the aforementioned coaxial phase cable and reduces the number of solder joints required.

[0059] The forward-extending tab 246 increases the span of each phase shifter printed circuit board 242 in the forward direction of the base station antenna 100. Since the cavity 220 is closed on all four main sides (i.e., the front, rear, and sidewalls), each phase shifter printed circuit board 242 is inserted into the corresponding cavity 220 from its top or bottom end (which is open). FIG. 1D As shown, each cavity 220 must therefore be formed deeper in the depth direction than the portion of the phase shifter printed circuit board 242 excluding the tab 246, so that the phase shifter printed circuit board 242 can be inserted into the corresponding cavity 220.

[0060] Although FIGS. 1C-1E Conventional cavity phase shifter assemblies 200 offer many advantages over non-cavity phase shifter assemblies, but may be difficult to manufacture. In base station antennas that include cavity phase shifter assemblies, typically many or all of the linear arrays included in the base station antenna may have associated cavity phase shifter assemblies. In some cases, the cavity phase shifter assembly can be formed by extruding the metal housing of all cavity phase shifter assemblies and reflectors into a single integral structure 250, such as... FIG. 2A As shown in the diagram. While this provides a structurally sound framework for the antenna, it also creates... FIG. 2A The large, monolithic structure 250 shown may be difficult and expensive. To overcome this difficulty, the base station antenna 260 may include multiple individually extruded metal housings 270, such as... FIG. 2BAs shown in the figure. Each metal housing 270 will typically have two cavities 280 formed therein, such that the metal housing 270 may include phase shifters for two polarized radiators of a linear array. As shown, the metal housing 270 may be mounted on a frame 290, providing a small gap between adjacent metal housings 270 to avoid contact between adjacent metal housings 270, which could otherwise act as a potential source of passive intermodulation (“PIM”) distortion. In some cases, the front wall 272 of the metal housing 270 may be used as a reflector for a base station antenna. In other cases, separate reflectors (not shown) may be mounted on the front wall 272 of the metal housing 270, with a thin dielectric layer disposed therebetween, such that each metal housing 270 is capacitively coupled to a separate reflector. FIG. 2B In some embodiments, each metal housing 270 may be an integral element comprising a pair of cavities 280 formed therein. The cavities 280 may have a front wall, a pair of side walls, and a rear wall, and may be open at each end as shown. The openings may be provided in some of the walls. For example, as... FIG. 2B As shown, the opening can be provided in the front wall 272, so that the output of the phase shifter can be referenced above. FIG. 1C The same method described above connects to the power supply board printed circuit board. Although FIG. 2B The smaller metal casing 270 shown can be compared to FIG. 2A The large composite structure 250 shown is easier to manufacture, but the extrusion process remains expensive. Additionally, the performance of the linear array may be somewhat reduced if a separate reflector is not provided, and if a reflector is provided, it increases weight, cost, and manufacturing complexity.

[0061] According to embodiments of the present invention, a base station antenna including a cavity phase shifter assembly is provided, which can be manufactured less costly and can exhibit increased performance and / or be less than conventional cavity phase shifter assemblies. The cavity phase shifter assembly according to embodiments of the present invention may include one or more metal housings and a separate metal cover. Each metal housing may include, for example, a sheet metal housing, which is stamped from a sheet metal and then bent to define one or more cavities having an open front portion. The metal cover may be positioned in front of the metal housing such that it covers the open front portion of each cavity. The metal cover may include, for example, a sheet metal cover. The metal housing may be attached to the metal cover using multiple connectors (e.g., bolts and nuts or twist-lock connectors). A thin dielectric element, such as a gasket, may be placed between the metal housing and the metal cover such that the metal housing is capacitively coupled to the metal cover. In other embodiments, a conductive element, such as a conductive rubber gasket or a conductive double-sided fabric strip, may be placed between the metal housing and the metal cover such that the metal housing is current-coupled to the metal cover in a manner that will not be a source of PIM distortion.

[0062] Each metal housing may include a pair of sidewalls extending in the longitudinal direction and a rear wall connecting the rear edges of the two sidewalls. A cavity is defined between the two sidewalls and the rear wall. The cavity is open in the front (i.e., the metal housing does not include a front wall that closes the front portion of each respective cavity). The metal housing may include a lip extending outward from the front portion of each sidewall. These lips may have openings that allow each metal housing to be attached to a metal cover by a connector extending through the openings and through an opening in a metal cover. In some embodiments, the ends of each cavity (in the longitudinal direction) may be open.

[0063] Phase shifters can be mounted in each cavity. Each phase shifter may include, for example, a phase shifter printed circuit board and one or more sliding dielectric blocks that together implement the sliding dielectric phase shifter. In some embodiments, the phase shifter printed circuit board may include forward-extending tabs, and output RF transmission lines may extend to the corresponding forward-extending tabs. The forward-extending tabs may extend through openings in a metal cover such that the forward-extending tabs are on the front side of the reflector of the base station antenna (note that the metal cover may act as a reflector).

[0064] A metal housing can be attached to a metal cap, such that the metal cap forms the front wall of each cavity. Since the cavities are open in the front portion before the metal cap is attached, each phase shifter printed circuit board can be mounted in its respective cavity by inserting the phase shifter from the front into its respective cavity. Because the phase shifter printed circuit board is mounted from the front, the cavity can have the same depth as the portion of the phase shifter printed circuit board excluding the forward-extending tabs, since these tabs extend through the openings in the metal cap when the metal housing is attached. In contrast, for conventional cavity phase shifter assemblies with cavities that are open only at their ends, the cavity depth must be at least as large as the portion of the phase shifter printed circuit board including the forward-extending tabs. Therefore, the cavity phase shifter according to an embodiment of the invention can have a reduced depth.

[0065] Now refer to FIGS. 3A-4 Embodiments of the invention are described in more detail, illustrating an exemplary cavity phase shifter assembly according to an embodiment of the invention. FIGS. 3A-4 The cavity phase shifter assembly shown can replace FIGS. 1C-1E The cavity phase shifter assembly 200 in, for example FIGS. 1A-1B It is used in the base station antenna 100.

[0066] FIG. 3A This is a schematic end view of a cavity phase shifter assembly 300 according to an embodiment of the present invention. FIG. 3B yes FIG. 3A A schematic front perspective view of one of the metal housings 310 of the cavity phase shifter assembly 300. FIG. 3C yes FIG. 3AA schematic front perspective view of the metal cover 330 shown. FIG. 3D It is inside the box marked 3D. FIG. 3A A magnified view of the part.

[0067] like FIG. 3A As shown, the cavity phase shifter assembly 300 includes a first metal housing and second metal housings 310-1, 310-2, and a metal cover 330. The cavity phase shifter assembly 300 also includes a plurality of connectors 340, such as bolt and nut pairs, for attaching the metal housings 310-1, 310-2 to the metal cover 330. Gaskets or other spacers 350 may be placed between the metal cover 330 and the metal housings 310-1, 310-2.

[0068] refer to FIG. 3A and FIG. 3B Each metal housing 310 may extend along a corresponding longitudinal axis L1. In some embodiments, the metal housing 310 may be formed from a sheet metal using stamping and bending operations well known to those skilled in the art. The sheet metal housing 310 may be formed at extremely low cost. In other embodiments, each metal housing 310 may include a plastic extrusion having a metal film or metal plating formed on at least one side thereon.

[0069] like FIG. 3A As shown, each metal housing 310 includes a first sidewall 312-1, a second sidewall 312-2, and a rear wall 314. As shown, the rear wall 314 can be integrally formed with the first and second sidewalls 312-1 and 312-2, and can connect the rear edges of the first and second sidewalls 312-1 and 312-2. A first lip 316-1 can extend outward from the front edge of the first sidewall 312-1, and a second lip 316-2 can extend outward from the front edge of the second sidewall 312-2. As shown, the first and second lips 316-1 and 316-2 can be integrally formed with the first and second sidewalls 312-1 and 312-2, and can extend outward (i.e., away from each other) from the front edges of the first and second sidewalls 312-1 and 312-2. When the cavity phase shifter assembly 300 is installed in the base station antenna 100, the first sidewall and the second sidewalls 312-1, 312-2 may have main surfaces extending in the vertical and forward directions of the base station antenna 100, while the rear wall 314 and the first lip and the second lip 316-1, 316-2 may have main surfaces extending in the vertical and horizontal directions of the base station antenna 100. FIG. 3B As shown, the length of each metal housing 310 in the vertical direction can be much greater than the width of the metal housing 310 in the horizontal direction or the depth of the metal housing 310 in the forward direction.

[0070] The first and second sidewalls 312-1, 312-2 of each metal housing 310, together with the rear wall 314, define a longitudinally extending cavity 320. For example... FIG. 3B As shown, the metal housing 310 does not include any front wall covering the front of the cavity 320, such that each cavity 320 has an open front. Similarly, the metal housing 310 does not include a top wall or bottom wall covering the respective top and bottom ends of each cavity 320, such that each cavity 320 may also have an open end.

[0071] In some embodiments, each pair of metal housings 310 may have an associated metal cover 330. In other embodiments, a single metal cover may be provided, which serves as a cover for all the metal housings 310 included in the base station antenna. In this case, the single metal cover may also serve as a reflector for the base station antenna. FIG. 3F The metal cover 330' is shown, which can act as a reflector for a base station antenna and can also serve as eight metal housings 310 ( FIG. 3F Metal cap (not shown in the image).

[0072] Connector 340 is used to attach metal housings 310-1, 310-2 to metal cover 330. In the depicted embodiment, each connector 340 includes a bolt 342 with a mating nut 344. Each lip 316 may include a plurality of openings 318, such as holes or slots along the length of the lip 316, as... FIG. 3B As best shown. The metal cap 330 may similarly include a plurality of openings 332 (e.g., holes or slots), which are aligned with openings 318 in corresponding lips 316, as shown. FIG. 3C As best shown. In the depicted embodiment, each connector 340 includes a combination of a bolt 342 and a nut 344. The bolt 342 can be inserted from the front through openings 318, 322, and the nut 344 can be tightened from the rear onto the corresponding bolt 342, such that the lip 316 of the metal housing 310 and the metal cap 330 are captured therebetween, thereby attaching each metal housing 310 to the metal cap 330. The rear surface of the metal cap 330 may extend in a plane parallel to the plane defined by the front surface of the first lip 316-1 and / or in a plane parallel to the plane defined by the front surface of the second lip 316-2.

[0073] Although connector 340 is in FIG. 3A The embodiment is a bolt / nut connector 340, but it should be understood that any suitable connector 340 can be used. For example, in other embodiments, a quarter-turn or half-turn connector can be used instead. FIG. 3A An example of a representative quarter-turn connector used in the bolt-nut pair shown is disclosed in U.S. Patent No. 10,907,675, published February 2, 2021, the entire contents of which are incorporated herein by reference.

[0074] As is known in the art, inconsistent metal-to-metal connections can cause PIM distortion in RF communication systems. To prevent such PIM distortion (or at least reduce the risk of such PIM distortion), one or more spacers 350 (e.g., multiple washers) can be placed between the metal housing 310 and the metal cover 330 to prevent direct contact between the metal cover 330 and the metal housing 310. In some embodiments, the spacer 350 may comprise a thin dielectric material. In such embodiments, the metal cover 330 can be capacitively coupled to the metal housing 310 via the dielectric spacer 350. In other embodiments, the spacer 350 may comprise a conductive material, such as a conductive rubber washer or a double-sided conductive fabric strip. In such embodiments, the metal cover 330 can be electrically connected to the metal housing 310 via the conductive spacer 350. In some embodiments, the conductive spacer 350 may comprise a resilient material, and the connector 340 may be tightened to ensure a consistent electrical connection on one side between the spacer 350 and the metal housing 310 and on the other side between the spacer and the metal cover 330. As shown, each connector 340 may also include a gasket 346.

[0075] Refer again FIG. 3A A first phase shifter 340-1 is installed in a first cavity 320-1, and a second phase shifter 340-2 is installed in a second cavity 320-2. Each phase shifter 340 may include, for example, a phase shifter printed circuit board 242 and one or more sliding dielectric blocks 348, on which RF transmission lines are formed. The phase shifter printed circuit board 242 can be connected to... FIG. 1E The phase shifter printed circuit board 242 shown is the same and is therefore identified using the same reference numerals, and further description thereof will be omitted here.

[0076] FIG. 3E This is an end view of a mid-frequency linear array assembly 370, which includes a cavity phase shifter assembly 300 and a linear array 380 of mid-frequency radiating elements 382 according to an embodiment of the present invention. The mid-frequency linear array assembly 380 can be used, for example, to implement... FIGS. 1A-1B The intermediate frequency band linear array assembly is one of the intermediate frequency band linear array assemblies of the base station antenna 100. The intermediate frequency band cavity phase shifter assembly 300 can be connected to a pair of RF ports 108 of the base station antenna 100 (one RF port for each of the two polarizations) by a corresponding RF feed cable (not shown).

[0077] As discussed above, FIG. 3EThe metal cover 330 shown may be part of the main reflector 110 of the base station antenna 100. A metal housing 310 is mounted behind the metal cover 330 / reflector 110, while a mid-band radiating element 382 is mounted in front of the metal cover 330 / reflector 110. Multiple openings 332 ( FIG. 3C A tab 246 of the phase shifter printed circuit board 242 is provided in the metal cover 330 / reflector 110 to allow the output RF transmission line on the forward-extending tab 246 of the phase shifter printed circuit board 242 to extend from the cavity 320 to connect to the feed board printed circuit board of the intermediate frequency linear array 380 or directly to the radiating element 382. Although not shown in the figure, in other embodiments, the feed stem of the radiating element may have a rearward-extending tab that passes through the opening 332 in the metal cover 330 / reflector 110, such that the signal traces and / or ground lines on the feed stem can be electrically connected (e.g., by soldering) to the output of the phase shifter printed circuit board 242.

[0078] The cavity phase shifter assembly 300 can be manufactured more efficiently than the one mentioned above. FIGS. 1C-1E and FIGS. 2A-2B The cavity phase shifter assembly discussed is inexpensive. Furthermore, the cavity phase shifter assembly 300 can be smaller than many conventional cavity phase shifter assemblies. (See above reference.) FIG. 1E In many cases, the phase shifter printed circuit board 242 used in a cavity phase shifter assembly may have a forward-extending tab 246 extending from the front wall of a metal housing that defines a cavity for physical and electrical connection to or direct connection to the feed board printed circuit board of a linear array to the radiating elements of the linear array. Since conventional metal housings for cavity phase shifters have two side walls, a rear wall and a front wall, and are therefore open only at their upper and lower ends, the phase shifter printed circuit board for such cavity phase shifter assemblies is inserted into the cavity from either the upper or lower end. If these printed circuit boards include the forward-extending tab 246, the depth of each cavity must be at least as large as the width of the phase shifter printed circuit board 242 including the forward-extending tab 246 (i.e., the span of the phase shifter printed circuit board in the depth direction when mounted within the cavity), even if the phase shifter printed circuit board 242 is pushed forward when mounted within the cavity such that the forward-extending tab 246 extends through the front wall of the metal housing. In other words, the cavity depth must be increased by the length of the forward-extending tab 246 in the forward direction so that the phase shifter printed circuit board 242 can be inserted into the corresponding cavity. This requires a larger metal housing, increasing the size, weight, and cost of the cavity phase shifter assembly.

[0079] In contrast, the cavity phase shifter assembly according to an embodiment of the invention includes a cavity 320 with an open front portion, which allows the phase shifter printed circuit board 242 to be easily inserted into the corresponding cavity (before the metal housing 310 is attached to the metal cover 330), such that the forward-extending tab 246 extends forward from the cavity 320, while the rear edge of the phase shifter printed circuit board 242 rests against the rear wall 314 of the cavity 320. Therefore, the cavity 320 can be sized to have a depth equal to the span in the depth direction of the portion of the phase shifter printed circuit board 242 excluding the forward-extending tab 246, and thus the cavity 320 can be shallower than many conventional cavities.

[0080] This design can be particularly advantageous when used in base station antennas in which a forward-extending tab 246 of the phase shifter printed circuit board 242 acts as part of the feed handle of the radiating element 382 of the linear array 380 associated with the cavity phase shifter assembly 300. In such base station antennas, the length of the forward-extending tab 246 in the depth (forward) direction typically exceeds one-quarter of the wavelength of the center frequency of the operating band of the radiating element. Such base station antennas are described in U.S. Provisional Patent Application Serial No. 63 / 680,302 (hereinafter referred to as the “'302 application”), filed August 7, 2024, the entire contents of which are incorporated herein by reference. Since increasing the cavity depth to match the depth of the phase shifter printed circuit board disclosed in the '302 application is generally commercially impractical, the '302 application proposes to partially or completely omit the rear wall of the metal housing of the cavity phase shifter disclosed therein. However, this can introduce unwanted resonances that may need to be addressed and can potentially increase RF losses and / or interference from other RF sources. By providing an open front cavity 320 that can be later covered by a removable metal cover 330, the cavity phase shifter assembly 300 according to an embodiment of the invention can provide improved performance.

[0081] Refer again FIGS. 3A-3E According to some embodiments of the present invention, a cavity phase shifter assembly 300 is provided, comprising: a metal housing 310 extending along a longitudinal axis L1, the metal housing 310 having a first sidewall 312-1 and a second sidewall 312-2, the first sidewall and the second sidewall being connected by a rear wall 314 to define a first cavity 320 having an open front portion; and a metal cover 330 positioned in front of the open front portion of the first cavity 320.

[0082] The metal housing 310 may further include a first lip 316-1 extending away from the first cavity 320 and a second lip 316-2 also extending away from the first cavity 320. The first lip 316-1 may extend parallel to the main surface of the metal cover 330 (e.g., the rear surface of the metal cover 330), and the second lip 316-2 may also extend parallel to the main surface of the metal cover 330. The cavity phase shifter assembly may further include a spacer 350 disposed between the metal housing 310 and the metal cover 330. The spacer 350 may include a dielectric spacer (e.g., a rubber or plastic gasket) or may be formed of a conductive material (e.g., in an exemplary embodiment, a conductive rubber spacer or a double-sided conductive fabric strip). The metal cover 330 may include a plurality of openings 332 providing access to the first cavity 320.

[0083] The cavity phase shifter assembly 300 may also include multiple connectors 340, such as multiple pairs of bolts 342 and nuts 344 or multiple torsion connectors. The connectors 340 can be used to removably attach the metal housing 310 to the metal cover 330.

[0084] In some embodiments, the metal housing 310 may include a stamped and bent metal sheet. In other embodiments, the metal housing 310 may include an extruded or molded plastic frame having a metallized film or metal plating on at least one side. In some embodiments, the metal cover 330 may include a single metal sheet. The metal cover 330 may be stamped from a larger metal sheet and may have openings stamped therein. In some embodiments, the metal cover 330 may also be bent (e.g., bent at the edges to form a support lip, RF choke, etc.). In some embodiments, the metal cover 330 may include a primary reflector for a base station antenna that acts as a reflector for an array of multiple radiating elements.

[0085] The cavity phase shifter assembly 300 may also include a phase shifter printed circuit board 242 in the first cavity 320. The phase shifter printed circuit board 242 may include one or more forward-extending tabs 246 extending through a corresponding opening 332 in the metal cover 330.

[0086] FIG. 4 This is a schematic end view of a cavity phase shifter assembly 400 according to another embodiment of the present invention. The cavity phase shifter assembly 400 can be very similar to... FIGS. 3A-3D The cavity phase shifter assembly 300 differs in that it includes a single metal housing 410 defining two cavities 420-1, 420-2, instead of having two separate metal cavities 310-1, 310-2 defining two respective cavities 320-1, 320-2 as in the case of the cavity phase shifter assembly 300.

[0087] Cavity phase shifter assembly 400 allows the two cavities 420-1, 420-2 to be positioned closer to each other and may require fewer metal plates, thus reducing antenna weight and material costs. It may also require fewer connectors 340, further reducing costs and simplifying antenna assembly. Since cavity phase shifter assembly 400 may otherwise be identical to cavity phase shifter assembly 300, further description of cavity phase shifter assembly 400 is omitted here.

[0088] like FIG. 4 As shown, according to another embodiment of the invention, a cavity phase shifter assembly 400 is provided, comprising a metal housing 410 including a first cavity 420-1 having an open front portion and a second cavity 420-2 also having an open front portion. A first phase shifter 240-1 is mounted in the first cavity 420-1, and a second phase shifter 240-2 is mounted in the second cavity 420-2. The cavity phase shifter assembly 400 also includes a metal cover 430 positioned in front of the open front portion of the first cavity 420-1 and in front of the open front portion of the second cavity 420-2.

[0089] The invention has been described above with reference to the accompanying drawings. The invention is not limited to the embodiments shown. Rather, these embodiments are intended to fully and completely disclose the invention to those skilled in the art. In the drawings, the same reference numerals consistently denote the same elements. For clarity, the thickness and dimensions of some parts may be exaggerated.

[0090] For ease of description, spatially relative terms such as “below,” “under,” “lower,” “above,” “upper,” “top,” “bottom,” etc., are used herein to describe the relationship of one element or feature as shown in the accompanying drawings to one or more other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms are also intended to cover different orientations of the device in use or operation. For example, if the device in the figures is flipped, an element described as “below” or “under” other elements or features would be oriented as “above” other elements or features. Thus, the exemplary term “below” can encompass both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or other orientations), and the spatially relative descriptive terms used herein shall be interpreted accordingly.

[0091] In this document, unless otherwise stated, the terms “attachment,” “connection,” “interconnection,” “contact,” “mounting,” “coupling,” etc., may refer to direct or indirect attachment or coupling between elements.

[0092] For the sake of brevity and / or clarity, well-known features or constructs may not be described in detail. As used herein, the expression "and / or" includes any and all combinations of one or more of the related listed items.

[0093] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” are also intended to include the plural forms. It will be further understood that, when used in this specification, the terms “comprises / comprising,” “includes,” and / or “including” specify the presence of the said feature, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

Claims

1. A cavity phase shifter assembly, comprising: A metal housing extending along a longitudinal axis, the metal housing having a first sidewall and a second sidewall connected by a rear wall to define a first cavity having an open front portion; as well as A metal cap, positioned in front of the open front portion of the first cavity.

2. The cavity phase shifter assembly of claim 1, wherein the metal cap includes a plurality of openings providing access to the first cavity.

3. The cavity phase shifter assembly of claim 1, wherein the metal housing further includes a first lip extending away from the first cavity and a second lip extending away from the first cavity.

4. The cavity phase shifter assembly of claim 3, wherein the first lip extends parallel to the main surface of the metal cap, and the second lip also extends parallel to the main surface of the metal cap.

5. The cavity phase shifter assembly of claim 1 further includes a dielectric material disposed between the metal housing and the metal cover.

6. The cavity phase shifter assembly of claim 5, wherein the dielectric material comprises a gasket.

7. The cavity phase shifter assembly of claim 1, wherein the metal housing further comprises a third sidewall and a fourth sidewall, the third sidewall and the fourth sidewall being connected by a second rear wall to define a second cavity having an open front portion.

8. The cavity phase shifter assembly of claim 7, wherein the metal cap is positioned in front of the open front portion of the second cavity.

9. The cavity phase shifter assembly of claim 1, wherein a plurality of connectors attach the metal housing to the metal cover.

10. The cavity phase shifter assembly of claim 1, wherein the metal housing comprises a metal plate.

11. The cavity phase shifter assembly of claim 1, wherein the metal housing comprises metallized plastic.

12. The cavity phase shifter assembly of claim 1, wherein the metal cover comprises a metal plate.

13. The cavity phase shifter assembly of claim 1, wherein the metal cover comprises a reflector for a base station antenna.

14. The cavity phase shifter assembly of claim 2, further comprising a phase shifter printed circuit board in the first cavity, wherein the phase shifter printed circuit board includes a forward-extending tab extending through a first opening in an opening in the metal cover.

15. A cavity phase shifter assembly, comprising: A metal housing, the metal housing comprising a first cavity having an open front portion and a second cavity having an open front portion; The first phase shifter assembly in the first cavity; The second phase shifter assembly in the second cavity, and A metal cap, positioned in front of the open front portion of the first cavity and the open front portion of the second cavity.

16. The cavity phase shifter assembly of claim 15, wherein the metal cap includes a plurality of openings providing access to the first cavity and the second cavity.

17. The cavity phase shifter assembly of claim 15, wherein the metal housing comprises: A first sidewall and a second sidewall, the first sidewall and the second sidewall being connected by a first rear wall to define the first cavity; as well as The third and fourth sidewalls are connected by the second rear wall to define the second cavity.

18. The cavity phase shifter assembly of claim 17, wherein the metal housing further includes a first lip extending away from the first cavity and a second lip extending away from the first cavity and toward the second cavity.

19. The cavity phase shifter assembly of claim 17, wherein the first lip extends parallel to the main surface of the metal cap, and the second lip also extends parallel to the main surface of the metal cap.

20. The cavity phase shifter assembly of claim 15, further comprising a separator disposed between the metal housing and the metal cover.

21. The cavity phase shifter assembly of claim 20, wherein the separator comprises a resilient conductive separator.

22. The cavity phase shifter assembly of claim 20, wherein the separator comprises a dielectric material and the metal cap is capacitively coupled to the metal housing.

23. The cavity phase shifter assembly of claim 15, wherein a plurality of connectors attach the metal housing to the metal cover.

24. The cavity phase shifter assembly of claim 15, wherein the metal housing comprises a metal plate.

25. The cavity phase shifter assembly of claim 15, wherein the metal housing comprises metallized plastic.

26. The cavity phase shifter assembly of claim 15, wherein the metal cover comprises a metal plate.

27. The cavity phase shifter assembly of claim 15, wherein the metal cover comprises a portion of the reflector of the base station antenna.

28. The cavity phase shifter assembly of claim 16, further comprising a first phase shifter printed circuit board in the first cavity and a second phase shifter printed circuit board in the second cavity, wherein the first phase shifter printed circuit board includes a forward-extending tab extending through a first opening in an opening in the metal cover.

29. A cavity phase shifter assembly, comprising: A metal housing extending along a first longitudinal axis, the metal housing comprising: First sidewall; Second sidewall; Rear wall, which connects the first side wall to the second side wall; A first lip margin, the first lip margin extending outward from the anterior edge of the first sidewall; and The second lip margin extends outward from the anterior edge of the second sidewall; and A metal cap that extends parallel to the first lip and the second lip.

30. The cavity phase shifter assembly of claim 29, wherein the first sidewall, the second sidewall, and the rear wall define a first cavity having an open front portion, and the metal cap is positioned in front of the open front portion of the first cavity.

31. The cavity phase shifter assembly of claim 30, wherein the metal cap includes a plurality of openings that provide access to the first cavity and the second cavity.

32. The cavity phase shifter assembly of claim 29, wherein the first lip extends parallel to the main surface of the metal cap, and the second lip also extends parallel to the main surface of the metal cap.

33. The cavity phase shifter assembly of claim 29, further comprising a separator disposed between the metal housing and the metal cover.

34. The cavity phase shifter assembly of claim 33, wherein the separator comprises a conductive separator.

35. The cavity phase shifter assembly of claim 33, wherein the separator comprises a dielectric material and the metal cap is capacitively coupled to the metal housing.

36. The cavity phase shifter assembly of claim 29, wherein a plurality of connectors attach the metal housing to the metal cover.

37. The cavity phase shifter assembly of claim 29, wherein the metal housing comprises a metal plate.

38. The cavity phase shifter assembly of claim 29, wherein the metal housing comprises metallized plastic.

39. The cavity phase shifter assembly of claim 29, wherein the metal cover comprises a metal plate.

40. The cavity phase shifter assembly of claim 29, wherein the metal cover comprises a portion of the reflector of the base station antenna.

41. The cavity phase shifter assembly of claim 29, wherein the rear edge of the phase shifter printed circuit board contacts the rear wall of the metal housing.

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