Base station antenna with frequency selective surface having unit cells including inductor features

Abstract

The base station antenna includes at least two frequency selective surfaces / layers with an array of low-band radiating elements protruding forward of a front one of the FSS layers. The FSS layer is provided with unit cells having inductor features, and may be provided as two stacked layers, each including unit cells having aligned inductor features of different inductor values, thereby providing improved reflectivity and ultra wide band performance. The antenna array is located behind a rear of the at least two FSS layers and is configured to transmit signals through the at least two FSS layers and out of a front antenna cover of the base station antenna.

Description

[0001] Related Applications

[0002] This patent application claims the benefit and priority of U.S. Provisional Application Serial No. 63 / 385,670, filed on December 1, 2022, the content of which is hereby incorporated by reference herein as if set forth in full herein. Background of the Invention

[0003] The present invention generally relates to wireless communication and, more particularly, to base station antennas for cellular communication systems.

[0004] 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" served by corresponding base stations. A base station may include one or more antennas configured to provide two-way radio frequency ("RF") communication with mobile users within the cell served by the base station. In many cases, each cell is divided into "sectors". In a common configuration, a hexagonal-shaped cell is divided into three 120° sectors in the azimuth plane, and each sector is served by one or more base station antennas having an azimuthal half-power beamwidth (HPBW) of approximately 65°. Typically, base station antennas are mounted on towers or other elevated structures, where the radiation pattern (also referred to herein as the "antenna beam") is generated by the outward-facing base station antennas. Base station antennas are typically implemented as linear or planar phased arrays of radiating elements.

[0005] To accommodate the growing cellular traffic, cellular carriers have added cellular services in various new frequency bands. To increase capacity without further increasing the number of base station antennas, multi-band base station antennas have been introduced, which include multiple linear arrays of radiating elements. Additionally, base station antennas are now being deployed that include "beamforming" arrays of radiating elements, the beamforming arrays of radiating elements including multiple columns of radiating elements. The radio devices for these beamforming arrays can be integrated into the antenna such that the antenna can perform active beamforming (i.e., the shape of the antenna beam generated by the antenna can be adaptively changed to improve the performance of the antenna). These beamforming arrays typically operate in various parts of higher frequency bands, such as the 3.3 - 5.8 GHz band. An antenna with an integrated radio device is referred to as an "active antenna", and the integrated radio device can adjust the amplitude and / or phase of the sub-components of the RF signals transmitted through individual radiating elements or small groupings thereof. An active antenna can generate a narrow beamwidth, high-gain antenna beam by changing the amplitude and / or phase of the sub-components of the RF signals transmitted through the antenna and can steer the generated antenna beam in different directions.

[0006] With the development of wireless communication technology, integrated base station antennas including passive modules and active antenna modules with active antennas have emerged. The passive module may include one or more passive arrays of radiating elements, the one or more passive arrays being configured to generate relatively static antenna beams, such as an antenna beam configured to cover a 120-degree sector (in the azimuth plane) of the base station antenna. The passive array may include an array operating according to second-generation (2G), third-generation (3G), or fourth-generation (4G) cellular standards. These passive arrays are not configured to perform active beamforming operations, but they typically have remote electrical tilt (RET) capabilities, which allow the shape of the antenna beam to be changed through an electromechanical device to change the coverage area of the antenna beam. The active antenna module may include one or more arrays of radiating elements operating according to fifth-generation (or later) cellular standards. These arrays typically perform individual amplitude and phase control of a subset of the radiating elements therein and perform active beamforming.

[0007] FIG. 1 shows an example of a prior art base station antenna 10 including a pair of beamforming arrays and associated beamforming radio devices. When the antenna 10 is installed for normal operation, the base station antenna 10 is typically installed with the longitudinal axis L of the antenna 10 extending along a vertical axis (e.g., the longitudinal axis L may be generally perpendicular to the plane defined by the horizon). The front surface of the antenna 10 is mounted opposite a tower or other mounting structure and points to the coverage area of the antenna 10. The antenna 10 includes a radome 11 and a top cover 20. The antenna 10 also includes a bottom cover 30, which includes a plurality of connectors 40 mounted therein. As shown, the radome 11, the top cover 20, and the bottom cover 30 define the outer housing 10h of the antenna 10. The antenna assembly is housed within the housing 10h.

[0008] The antenna 10 may include one or more radio devices mounted to the rear of the housing 10h. Heat generated in the (multiple) radio devices is transferred to a radiator and dissipated to its fins (not shown). Other details of an exemplary conventional base station antenna can be found in co-pending WO2019 / 236203 and WO2020 / 072880, the contents of which are incorporated herein by reference as if recited in full herein. SUMMARY OF THE INVENTION

[0009] Embodiments of the present invention relate to a base station antenna having one or more frequency selective surface (FSS) layers, the one or more frequency selective surface layers being configured with unit cells having inductor features to allow high-frequency band radiating elements to propagate electromagnetic waves through apertures and to reflect low-frequency band signals from low-frequency band radiating elements in front of the one or more FSS layers.

[0010] Aspects of the present invention relate to a base station antenna, the base station antenna comprising: a first frequency selective surface (FSS), the first frequency selective surface having a first array of unit cells; and a second FSS, the second FSS having a second array of unit cells. The first FSS is stacked in front of the second FSS in the Z direction in the base station antenna. Each unit cell in the first array of unit cells and each unit cell in the second array of unit cells include a plurality of spaced apart inductor structures, and a first unit cell in the first array of unit cells is aligned with a first unit cell in the second array of unit cells in the X-Y direction, whereby the corresponding inductor structures of the first unit cell are aligned with the corresponding inductor structures of the first unit cell in the second array of unit cells.

[0011] The first unit cell in the first array of unit cells may have a perimeter, wherein a first adjacent unit cell and a second adjacent unit cell share a perimeter side, and the inductor structures of the first adjacent unit cell and the second adjacent unit cell may be electrically connected.

[0012] The inductor structures of the first unit cell in the first array and the first unit cell in the second array may be arranged to be located on the outer perimeter of the corresponding first unit cell or on a curved protrusion adjacent to the outer perimeter of the corresponding first unit cell.

[0013] The first unit cell in the first array of unit cells and the first unit cell in the second array of unit cells may each have a center and four linear segments protruding outward from the center. The four linear segments may be orthogonal to each other, and the four linear segments may each be incorporated into at least one of the inductor structures of their corresponding inductor structures.

[0014] The corresponding inductor structure of each unit cell may have protrusions serially protruding outward from opposite sides of the lateral or longitudinal centerline of the corresponding linear segment. The protrusions of the inductor structure of the first unit cell in the second array may extend beyond the boundaries of the protrusions of the first unit cell in the first array of unit cells.

[0015] The inductor structures of adjacent unit cells in the first array of unit cells may define a parallel inductor circuit.

[0016] One inductor structure of the first unit cell in the first array of unit cells may be incorporated into one inductor structure of an adjacent second unit cell in the first array of unit cells at the shared perimeter side.

[0017] The inductor structures may be located only on the perimeters of the corresponding unit cells in the first array of unit cells and the second array of unit cells.

[0018] The first unit cell in the first array of the unit cells and the second array of the unit cells may further include a curved segment surrounding the center. The four linear segments may extend from four sides of the curved segment surrounding the center.

[0019] The four linear segments may be internal linear segments, and the first unit cell may further include four external linear segments. One of the inductor structures in the inductor structure may be located between a pair of external linear segments and the internal linear segment.

[0020] The base station antenna may further include a third FSS located behind the second FSS, and the third FSS has a third array of unit cells.

[0021] The base station antenna may further include: a passive antenna having the first FSS and the second FSS in a housing; and an active antenna unit located behind the housing.

[0022] The base station antenna may further include a first plurality of radiating elements located in front of the first FSS and a second plurality of radiating elements located behind the second FSS.

[0023] The first plurality of radiating elements may operate in a first frequency band, and the second plurality of radiating elements may operate in a second frequency band.

[0024] The first plurality of radiating elements may have low-frequency band radiating elements configured to operate in the first frequency band, and the second plurality of radiating elements may have higher-frequency band radiating elements configured to operate in the second frequency band, and the second frequency band covers frequencies higher than the first frequency band.

[0025] The first FSS and the second FSS may be configured to allow RF energy in the second frequency band to propagate through the first FSS and the second FSS.

[0026] The first FSS may have a first subset of the first array of the unit cells, and the first subset is configured to block and / or reflect RF energy in the first frequency band while allowing RF energy in the second frequency band to propagate through the first FSS. The first FSS may further have a second subset of the first array of the unit cells, and the second subset is configured to block and / or reflect RF energy in the first frequency band and RF energy in the third frequency band. The third frequency band has a frequency between the first frequency band and the second frequency band.

[0027] A first subset of the first array of the unit cells may be located at an upper portion of the base station antenna. A second subset of the first array of the unit cells may have unit cells to the right of the first subset of the unit cells and may also have unit cells to the left of the first subset of the unit cells.

[0028] The first plurality of radiating elements may have high-band radiating elements operating in at least a portion of the 3.2 - 4.1 GHz band, and the second plurality of radiating elements may have radiating elements operating in at least a portion of a band lower than the high-band radiating elements.

[0029] The first FSS and the second FSS may be configured to allow RF energy in at least a portion of the 3.2 - 4.1 GHz band to propagate through the first FSS and the second FSS.

[0030] The second plurality of radiating elements may be arranged as a multi-column array in the active antenna module.

[0031] At least some of the unit cells in the first array of the unit cells and / or the second array of the unit cells may include at least one transmission line (TX) segment configured to be electrically coupled to at least one inductor structure.

[0032] The length of the at least one TX line segment may be configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

[0033] The length of the at least one TX line segment may be approximately half a wavelength of a defined frequency response point. Optionally, the defined frequency may be a second frequency response point f2 such that the unit cell defines a dual-response frequency band.

[0034] Some aspects of the present invention relate to a base station antenna including: a first frequency selective surface (FSS) including a first array of unit cells; and a second FSS including a second array of unit cells. The first FSS is stacked in front of the second FSS in the Z direction in the base station antenna. At least some of the unit cells in the first array of the unit cells and the second array of the unit cells are configured to provide an equivalent circuit including at least one inductor and at least one transmission line (TX) segment configured to be electrically coupled to the at least one inductor.

[0035] The length of the at least one TX line segment may be configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

[0036] The length of the at least one TX line segment can be approximately half a wavelength that defines a frequency response point.

[0037] The unit cells provided by the first array and the unit cells provided by the second array can be electrically coupled.

[0038] A first unit cell in the first array of unit cells can be electrically coupled to a first unit cell in the second array of unit cells, whereby the first unit cells cooperate to define an equivalent circuit to reject or block radio frequency signals from radiating elements operating in a first frequency band and pass signals from radiating elements operating in a second frequency band.

[0039] Additionally, other embodiments relate to a grid reflector for a base station antenna, the grid reflector including a frequency selective surface (FSS), the frequency selective surface including an array of unit cells. At least some of the unit cells in the array of unit cells have at least one transmission line (TX) segment.

[0040] The length of the at least one TX line segment is approximately half a wavelength of a defined frequency.

[0041] The at least one TX line segment can be configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

[0042] At least some of the unit cells having the at least one transmission line segment reject radio frequency signals in a first frequency band and a second larger frequency band corresponding to the defined frequency.

[0043] The at least one TX line segment can include adjacent parallel conductive lines.

[0044] Further, other embodiments relate to a grid reflector for a base station antenna, the grid reflector including a frequency selective surface (FSS), the frequency selective surface including a first array of unit cells having a first configuration and a second array of cells having a second configuration. The first array includes unit cells having a square shape, and the second array includes unit cells having a hexagonal shape. The first array extends inwards across 30 - 80% of the width of the FSS, and the second array is arranged in two columns on the right and left portions of the first array.

[0045] At least some of the unit cells in the array of unit cells can include at least one transmission line (TX) segment, the length of the at least one transmission line segment being configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

[0046] The FSS can be configured to have a response frequency f0 of about 2.5 GHz and can provide a band - pass frequency range and a band - stop frequency range.

[0047] The at least one TX line segment can have a length L, which is about half - wavelength that defines a frequency - response point.

[0048] The base - station antenna can include a passive module and / or a passive antenna assembly and an active antenna module, and the active antenna module can be mounted at a position corresponding to the frequency - selective surface.

[0049] According to an embodiment of the present disclosure, the frequency - selective surface is provided as a first frequency - selective surface and a second frequency - selective surface, one stacked in front of the other, and can be configured to allow electromagnetic waves emitted by the active module to pass through.

[0050] It should be noted that various aspects of the present disclosure described for one embodiment can be included in other different embodiments, even if not specifically described for the other different embodiments. In other words, the features of all embodiments and / or any embodiment can be combined in any manner and / or combination as long as they are not contradictory to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG. 1 is a perspective view of a base - station antenna of the prior art.

[0052] Figure 2A is a rear perspective view of an exemplary base - station antenna coupled to an active antenna module according to an embodiment of the present invention.

[0053] Figure 2B is a side - rear perspective view of another exemplary base - station antenna coupled to an active antenna module according to an embodiment of the present invention.

[0054] Figure 3 is an exemplary main reflector that can be provided in a base - station antenna such as Figure 2A or Figure 2B shown in a base - station antenna according to an embodiment of the present invention.

[0055] Figure 4A is a perspective view of a grid reflector of a base - station antenna according to an embodiment of the present invention.

[0056] Figure 4B is Figure 4A a front view of the grid reflector shown in

[0057] Figure 5 is an extremely magnified unit cell of a grid reflector of a base - station antenna according to an embodiment of the present invention.

[0058] Figure 6Is a schematic top view of a first FSS layer and a second FSS layer stacked in the front-rear (Z) direction according to an embodiment of the present invention. Each unit cell of the first FSS layer and the second FSS layer has an inductor characteristic of the corresponding FSS.

[0059] Figure 7 Is a schematic top view of a first FSS layer, a second FSS layer, and a third FSS layer stacked in the front-rear (Z) direction according to an embodiment of the present invention. Each unit cell of the first FSS layer, the second FSS layer, and the third FSS layer has an inductor characteristic of the corresponding FSS.

[0060] Figure 8 Is according to an embodiment of the present invention and has aligned unit cells (aligned in the X and Y directions) Figure 6 Greatly enlarged front view of the first FSS layer and the second FSS layer shown in

[0061] Figure 9 Is according to an embodiment of the present invention Figure 8 Greatly enlarged front view of adjacent unit cells of the first FSS layer and the second FSS layer shown in

[0062] Figure 10A Is a greatly enlarged front view of another embodiment of a unit cell having an inductor characteristic according to an embodiment of the present invention.

[0063] Figure 10B Is according to an embodiment of the present invention and is similar to Figure 10A Greatly enlarged front view of another embodiment of a unit cell having an inductor characteristic.

[0064] Figure 10C Is according to an embodiment of the present invention and is provided by Figure 10B and / or Figure 10C Exemplary broadband FSS equivalent circuit provided by the unit cell of

[0065] Figure 11 Is a greatly enlarged front view of yet another embodiment of a unit cell having an inductor characteristic according to an embodiment of the present invention.

[0066] Figure 12 Is a greatly enlarged front view of an additional embodiment of a unit cell having an inductor characteristic according to an embodiment of the present invention.

[0067] Figure 13 Is according to an embodiment of the present invention Figure 12 Greatly enlarged view of adjacent unit cells of the configuration shown in

[0068] Figure 14Schematic diagram of two adjacent unit cells according to an embodiment of the present invention, showing the centers a, b of the corresponding adjacent unit cells and exemplary currents.

[0069] Figure 15 Schematic diagram of a unit cell of the FSS layer according to an embodiment of the present invention, showing an exemplary radiation direction.

[0070] Figure 16A Exemplary equivalent circuit provided by the unit cell features of an embodiment of the present invention.

[0071] Figure 16B Exemplary equivalent circuit provided by the unit cell features of an embodiment of the present invention.

[0072] Figure 16C Graph of the simulated response (dB) of an exemplary broadband FSS having horizontal and vertical equivalent circuits according to an embodiment of the present invention, relative to frequency (GHz), where the horizontal and vertical equivalent circuits are provided by unit cells having Figure 16A and 16B of the horizontal and vertical equivalent circuits.

[0073] Figure 16D Graph of the simulated response of an exemplary broadband FSS having an equivalent circuit according to an embodiment of the present invention, relative to frequency (GHz), where the equivalent circuit is provided by a unit cell having Figure 16B of the equivalent circuit.

[0074] Figure 17A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention, the equivalent circuit having a transmission line segment in parallel with the parallel LC shown in Figure 16B .

[0075] Figure 17B For Figure 17A Graph of the simulated response (dB) of the equivalent circuit shown, relative to frequency (GHz) (with f0 and f2), compared to a reference response.

[0076] Figure 18A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention, the equivalent circuit having two TX line segments in parallel with the parallel LC shown in Figure 16B , providing 180 degrees at f2.

[0077] Figure 18B For Figure 18A Graph of the simulated response (dB) of the equivalent circuit shown, relative to frequency (GHz) (with f0 and f2).

[0078] Figure 19A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention.

[0079] Figure 19B A front view of the amplifying portion of the FSS according to an embodiment of the present invention, showing an exemplary configuration of a unit cell having the equivalent circuit shown in Figure 19A The equivalent circuit shown in.

[0080] Figure 19C For Figure 19A A graph of the simulation response (dB) versus frequency (GHz) (with f0 and f2) for the exemplary equivalent circuit shown in.

[0081] Figure 20A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention.

[0082] Figure 20B A front view of the amplifying portion of the FSS according to an embodiment of the present invention, showing an exemplary configuration of a unit cell having the equivalent circuit shown in Figure 20A The equivalent circuit shown in.

[0083] Figure 20C A graph of the simulation response (dB) versus frequency (GHz) (with f0 and f2), with the equivalent circuit shown in Figure 20A The equivalent circuit shown in.

[0084] Figure 21A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention.

[0085] Figure 21B A front view of the amplifying portion of the FSS according to an embodiment of the present invention, showing an exemplary configuration of a unit cell having the equivalent circuit shown in Figure 21A The equivalent circuit shown in.

[0086] Figure 21C Is Figure 21B A highly magnified front view of a part of the circuit features in, showing parallel lines.

[0087] Figure 21D For Figure 21A A graph of the simulation response (dB) versus frequency (GHz) (with f0 and f2) for the exemplary equivalent circuit shown in.

[0088] Figure 22A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention.

[0089] Figure 22BThe front view of the amplification part of the double-layer FSS according to an embodiment of the present invention, which shows having Figure 22A The exemplary configuration of the unit cell of the equivalent circuit shown in

[0090] Figure 22C Is for Figure 22A The graph of the simulation response (dB) of the exemplary equivalent circuit shown in

[0091] Figure 23A Another exemplary equivalent circuit provided by the unit cell features according to an embodiment of the present invention.

[0092] Figure 23B The front view of the amplification part of the double-layer FSS according to an embodiment of the present invention, which shows having Figure 23A The exemplary configuration of the unit cell of the equivalent circuit shown in

[0093] Figure 23C Is for Figure 22A The graph of the simulation response (dB) of the exemplary equivalent circuit shown in

[0094] Figure 24A The end view of a part of the exemplary multi-layer broadband frequency selective surface configuration (z direction facing up) according to an embodiment of the present invention.

[0095] Figure 24B Is Figure 24A The front view (x-y direction) of a part of one layer of the multi-layer broadband frequency selective surface configuration shown in

[0096] Figure 25A The exemplary equivalent circuit configuration of the double-layer broadband frequency selective surface according to an embodiment of the present invention.

[0097] Figure 25B The front view of the metamaterial according to an embodiment of the present invention, the metamaterial provides a unit cell corresponding to Figure 25A The equivalent circuit shown in

[0098] Figure 25C Shows according to an embodiment of the present invention providing Figure 25A The front view (x-y direction) of the dielectric material of the equivalent circuit shown in

[0099] Figure 26 And 27 The front view of an additional embodiment of the frequency selective surface according to an embodiment of the present invention.

[0100] Figure 28 is a front view of another embodiment of a frequency selective surface according to an embodiment of the present invention, which shows unit cells of different shapes in different regions of a reflector.

[0101] Figure 29A is applicable according to an embodiment of the present invention for Figure 28 an enlarged view of a single solid hexagonal patch of the hexagonal unit cell shown in

[0102] Figure 29B is an enlarged view of a single hexagonal-shaped unit cell according to an embodiment of the present invention, the single hexagonal-shaped unit cell being a hexagonal perimeter or loop around an open area or an area of a material different from the loop of the hexagonal unit cell shown in Figure 28

[0103] Figure 30A is a front side perspective view of an antenna assembly of a base station antenna and an exemplary grid reflector according to an embodiment of the present invention.

[0104] Figure 30B is Figure 30A an enlarged front side perspective view of the top portion of the antenna assembly and the grid reflector shown in

[0105] Figure 31A and 31B is a simplified side cross-sectional view of an exemplary base station antenna and a cooperative active antenna module according to an embodiment of the present invention.

[0106] Figure 32A - 32G is a front side partially transparent view of parts of a base station antenna according to an embodiment of the present invention, which shows an example of a stacked reflector configuration. DETAILED DESCRIPTION

[0107] Figure 2A shows a base station antenna 100 according to certain embodiments of the present invention. In the following description, the following terms will be used to describe the base station antenna 100, which terms assume that the base station antenna 100 is installed for use on a tower, pole, or other mounting structure, wherein the longitudinal axis L of the base station antenna 100 extends along a vertical axis, the front of the base station antenna 100 is mounted opposite to the tower, pole, or other mounting structure that points to the target coverage area of the base station antenna 100, and the rear 100r of the base station antenna 100 faces the tower or other mounting structure. It should be understood that the base station antenna 100 may not always be installed such that its longitudinal axis L extends along the vertical axis. For example, the base station antenna 100 may be slightly inclined relative to the vertical axis (e.g., less than 10°) such that the resulting antenna beams formed by the base station antenna 100 each have a small mechanical downtilt. ​

[0108] The base station antenna 100 may be coupled to or include at least one active antenna module 110. The term "active antenna module" is used interchangeably with "active antenna unit" and "AAU" and "active antenna", and refers to a cellular communication unit including radio circuitry and associated radiating elements. The radio circuitry is capable of electronically adjusting the amplitude and / or phase of sub-components of RF signals output to different radiating elements of an array or a group thereof. The active antenna module 110 includes radio circuitry and radiating elements (e.g., a multi-input multi-output (mMIMO) beamforming antenna array), and may include other components such as filters, calibration networks, an antenna interface signal group (AISG) controller, etc. The active antenna module 110 may be provided as a single integrated unit or as multiple stackable units, the multiple stackable units including, for example, a first sub-unit and a second sub-unit (e.g., a radio electronic unit (box) having radio circuitry and an antenna sub-unit (box) having a multi-column array of radiating elements), and the first sub-unit and the second sub-unit are stackably attached together in the front-to-back direction of the base station antenna 100, wherein the radiating elements 1195 of the antenna assembly 1190( Figure 31A 、 31B ) are closer to the front antenna cover 111f of the housing 100h of the base station antenna 100 / the antenna cover 111 of the base station antenna than the radio circuitry unit 1120. In some embodiments, the radiating elements 1195 may include sub-units separate from the radio circuitry, and the radiating element sub-units may be mounted inside the base station antenna 100 rather than outside the base station antenna 100.

[0109] As will be discussed further below, the base station antenna 100 includes an antenna assembly 190, which may be referred to as a "passive antenna assembly". The term "passive antenna assembly" refers to an antenna assembly having arrays of radiating elements, the arrays of radiating elements being coupled to radio devices external to the antenna, typically remote radio heads mounted adjacent to the base station antenna 100. The arrays of radiating elements included in the passive antenna assembly 190( Figure 20A ) are configured to form static antenna beams (e.g., antenna beams each configured to cover a sector of the base station). The passive antenna assembly 190 may include reflectors 170, 214 having radiating elements protruding in front of the reflectors, and the radiating elements may include one or more linear arrays of low-band radiating elements operating in all or part of the 617 - 960 MHz band and / or one or more linear arrays of mid-band radiating elements operating in all or part of the 1427 - 2690 MHz band. The passive antenna assembly 190 is mounted in the housing 100h of the base station antenna 100, and one or more active antenna modules 110 may be releasably (detachably) coupled (e.g., directly or indirectly attached) to the base station antenna 100.

[0110] The base station antenna 100 has a housing 100h. The housing 100h can be substantially rectangular, having a flat rectangular cross-section. The housing 100h can be arranged to define at least a portion of a radome 111, wherein at least the front side 111f is a dielectric cover configured to allow RF energy to pass through in a specific frequency band. The housing 100h can also be configured such that the rear portion 100r defines a rear side 111r radome opposite the front side radome 111f. Optionally, the housing 100h and / or the radome 111 may further include two (narrow) side walls 100s, 111s that face each other and extend rearwardly between the front side 111f and the rear side 111r. Generally, the top side 100t of the housing 100h can be sealed in a waterproof manner and can include an end cap 120, and the bottom 100b of the housing 100h can be sealed with a separate end cap 130. At least a portion of the front side 111f, the side walls 111s, and generally the rear side 111r of the radome 111 are substantially transparent to radio frequency (RF) energy within the operating frequency band of the base station antenna 100 and the active antenna module 110. The radome 111 can be formed of, for example, fiberglass or plastic.

[0111] Still referring to Figure 2A , in some embodiments, the active antenna module 110 can be located behind the base station antenna 100 and can optionally be attached to the base station antenna. The base station antenna 100 can include a frame 112 and attachment mounting brackets 113, 114. The rear portion 111r of the housing 100h can be a flat surface that extends along a common plane over its entire longitudinal extent or along at least a portion of its longitudinal extent.

[0112] Figure 2B It is shown that the rear surface 100r can include a recessed and / or stepped section 102 facing the active antenna module 110. The stepped section 102 is closer to the front portion 100f of the housing compared to the rear wall defined by the main section of the rear portion 100r of the housing 100h. The stepped section 102 can have a lateral and longitudinal extent that is the same as or greater than the lateral and longitudinal extent of the active antenna module 110. The rear surface 100r can also include a pair of spaced-apart longitudinally extending tracks 118 that engage adapter mounting brackets 1118 on the active antenna module 110 to attach the active antenna module 110 to the base station antenna housing 100h. However, other mounting configurations can be used.

[0113] Again referring to Figure 2A, in another embodiment, the rear surface 100r may include a plurality of longitudinally spaced mounting structure brackets extending rearwardly from the housing 100h, shown respectively as an upper bracket 115, an inner bracket 116, and a lower bracket 117. In some embodiments, the mounting structure brackets 115, 116, 117 may be configured to be coupled to one or more mounting structures, such as a tower, a pole, or a building (not shown). At least two of the mounting structure brackets 115, 116 may also be configured to be attached to the frame 112 of the base station antenna device in use. The frame 112 may extend over a sub-length of the longitudinal extent L of the base station antenna 100, where the sub-length is shown in Figure 2A as at least a major portion (at least 50% of its length). The frame 112 may include a top 112t, a bottom 112b, and two opposing long sides 112s extending between the top 112t and the bottom 112b. The frame 112 may have an open central space 112c that extends laterally between the sides 112s and longitudinally between the top 112t and the bottom 112b.

[0114] In use, the frame 112 may be configured such that various different active antenna modules 110 can be mounted to the frame 112 using suitable fitting mounting brackets 113, 114. Thus, various active antenna modules 110 can be interchangeably attached to the same base station antenna 100. Although the frame 112 is shown by way of example, other mounting systems may be used.

[0115] In some embodiments, a plurality of active antenna modules 110 may be simultaneously attached to the same base station antenna 100 at different longitudinal positions using one or more frames 112. Such active antenna modules 110 may have different sizes, such as different lengths and / or different widths and / or different thicknesses.

[0116] Now turning to Figure 3 , an exemplary main reflector 214 of the base station antenna 100 is shown. As shown, the main reflector 214 has a first section 2141 that extends a first longitudinal distance and merges into a second section 2142 that has spaced right and left segments 214s, the second section having a lateral extent d2 that is smaller than the lateral extent d1 of the first section 2141. An open inner region 14 may extend longitudinally and laterally around the second section 2142. In some embodiments, the open inner region 14 may have a lateral extent d3 that is 60 - 95% of the lateral extent d1. In some embodiments, the first section 2141 may have a greater longitudinal extent than the second section 2142, typically at least 20% greater, such as 30% - 80% greater.

[0117] Figure 4A and 4BAn exemplary grid reflector 170 of a base station antenna 100 is shown. The grid reflector 170 includes a frequency selective surface and may be interchangeably referred to as a "frequency selective reflector" or a "frequency selective surface layer". The grid reflector 170 may extend over a part or the entire lateral extent of the base station antenna 100 and at least a part of the length of the base station antenna 100.

[0118] In some embodiments, the grid reflector 170 may be electrically and / or mechanically coupled to the main reflector 214. In some embodiments, the grid reflector 170 may be positioned to be between the right and left sides 214s of the main reflector in the open inner region 14 ( Figure 3 ).

[0119] The grid reflector 170 may be provided as a non-metallic substrate, in which metal patches are arranged to define an array 171 of unit cells (also interchangeably referred to as "pattern cells"), or may be a metal grid and include an array 171 of unit cells.

[0120] The non-metallic substrate may be provided as a multi-layer printed circuit board (PCB), which may be rigid, semi-rigid or provided as a flexible circuit. The non-metallic substrate may be a plastic, polymer, copolymer having a metallized surface providing conductive patches.

[0121] The grid reflector 170 may be provided as a thin (e.g., 5 mil) PCB attached to a dielectric, such as a polycarbonate matching layer or other suitable substrate. The grid reflector 170 may be defined by a thicker PCB (e.g., 15 mil or 30 mil PCB).

[0122] The grid reflector 170 may be provided as a metal (e.g., aluminum) sheet, in which the grid is formed to form pattern cells / unit cells 171u (e.g., an array 171 of unit cells), which may be etched, perforated or laser formed through the metal sheet or otherwise formed.

[0123] The grid reflector 170 provides a frequency selective surface and / or substrate that is configured to allow RF energy (electromagnetic waves) in one or more first defined frequency ranges to pass through and is configured to reflect RF energy in a different second frequency band. The frequency selective surface and / or substrate may be interchangeably referred to as "FSS" herein. The grid reflector 170 of the base station antenna 100 may be located at least some of the antenna elements (see Figure 31A , 31Bbehind the radiation element 222) and may selectively reject some frequency bands and allow other frequency bands to pass through by including a frequency selective surface and / or a substrate to operate as a type of "spatial filter". See, for example, Ben A. Munk, Frequency Selective Surfaces: Theory and Design, ISBN: 978-0-471-37047-5; DOI: 10.1002 / 0471723770; April 2000, copyright John Wiley & Sons, Inc., the contents of which are hereby incorporated by reference as if set forth in full herein.

[0124] The frequency selective surface and / or substrate material of the grid reflector 170 may include one or more of metamaterials, suitable RF materials, or even air (although air may require more complex assembly). The term "metamaterial" refers to a composite electromagnetic (EM) material. Metamaterials may include sub-wavelength periodic microstructures.

[0125] The FSS 170 may be provided as one or more cooperating layers. The FSS 170 may include a substrate and a metal pattern formed on the dielectric substrate, the substrate having a dielectric constant in the range of about 2 - 4 (e.g., about 3.7) and a thickness of about 5 mils. The thickness may vary, but thinner materials may provide lower losses.

[0126] In some embodiments, the frequency selective substrate / surface 170 may be configured to act as a high-pass filter that substantially allows low-frequency band energy to be completely reflected (the FSS may act as a metal sheet), while allowing high-frequency band energy (e.g., about 3.5 GHz or higher) to pass through completely. Thus, the frequency selective substrate / surface is transparent or invisible to high-frequency band energy and can achieve a suitable out-of-band rejection response from the FSS. The FSS material may allow for a reduction in filters, or even elimination of the filter requirements of the backhaul radio device 1120 ( Figure 21A 、 21B ).

[0127] In some embodiments, the FSS 170 may be implemented, for example, using two or more closely spaced grids or FSS layers 1701, 1702 stacked in the Z direction, either or both of the grids or FSS layers may be provided as multi-layer printed circuit boards, wherein the different layers provide corresponding frequency selective surfaces, the corresponding frequency selective surfaces being configured such that electromagnetic waves within a predetermined frequency range cannot propagate through the FSS layers 1701, 1702, and allowing one or more other predetermined frequency ranges to pass through. Thus, the stacked FSS layers 1701, 1702 may be spaced apart in the Z direction and may cooperate to provide at least one rejection band and a (wider) passband.

[0128] Reference Figure 4A and 4B , shows a grid (frequency selective) reflector 170 according to an embodiment of the present disclosure. For example, the grid reflector 170 can be used in Figure 2A , 2B the base station antenna 10 shown in. The grid reflector 170 may include a body 21 and a frequency selective section 22 disposed in the body 21. At least the body 21 and / or the main reflector 214 may be metallic (e.g., formed of aluminum). The frequency selective section 22 may be disposed at a position corresponding to the installation position of the active antenna module 110 of the base station antenna 100, and may be configured to allow electromagnetic waves within a predetermined frequency range (e.g., high frequency electromagnetic waves within the range of 2300 to 5000 MHz or a part thereof, e.g., electromagnetic waves within the range of 2900 - 4000 MHz or 3400 - 5000 MHz) to pass through. In this way, when the base station antenna 100 is assembled, the high frequency electromagnetic waves emitted by the active antenna module 110 can pass through the frequency selective reflector 20 via the frequency selective section 22.

[0129] The frequency selective section 22 may be constituted by an array 171 of a plurality of pattern units or unit cells 171u periodically arranged in the lateral and longitudinal directions of the base station antenna. Each of the pattern units / unit cells 171u may have a predetermined pattern and may include a capacitor structure and an inductor structure connected in series ( Figure 16A ) or in parallel ( Figure 16B ) with the capacitor structure.

[0130] In addition, each pattern unit 171u of the array 171 may be electrically connected to each other through the inductor structure. For example, the inductor structure 2173 in each pattern unit / unit cell 171u may be electrically connected to the inductor structure 2173 of an adjacent adjacent pattern unit ( Figure 9 , 13 ).

[0131] The resonant frequency of the frequency selective section 22 can be configured by selecting or designing the patterns and dimensions of the capacitor structure and inductor structure of each pattern unit / unit cell 171 and the spacing and arrangement of the plurality of pattern units 171 such that electromagnetic waves within a predetermined frequency range can pass through the frequency selective section 22.

[0132] Reference Figure 5 , shows an exemplary unit cell (or "pattern unit") 171u of an array of unit cells or patterns 171 of an FSS170 according to an embodiment of the present disclosure. The unit cell 171u has a center 2171 and four linear segments 2172 extending orthogonally to each other, defining a "cross" pattern. The four linear segments 2172 project outward from the center 2171, and each of the four linear segments 2172 merges into a corresponding inductor feature 2173 extending laterally or longitudinally from a corresponding side 171s of the perimeter 171p of the corresponding unit cell 171u.

[0133] Each unit cell 171u can have a simple shape so as to have a small impact on both small and large incident angles. Positioning the inductor features 2173 to extend adjacent to each of the four outer peripheral sides 170s can provide improved performance at the operating frequency band, which can allow the inductance to be easily adjusted for the s-parameters of the operating frequency bands of different base station antennas 100. This inductor feature structure can also have broadband characteristics.

[0134] Figure 6 Shows that the base station antenna 100 can include at least a first FSS layer 1701 and a second FSS layer 1702 stacked in the front-back (Z) direction, and each FSS layer can include an array of unit cells 171.

[0135] Each FSS layer 1701, 1702 can be spaced apart from each other by about 1 / 10 - 1 / 2 of the operating wavelength, for example, about 1 / 4 of the operating wavelength of the high-band radiation element 1195 behind the second FSS1702 or the low-band radiation element 222 in front of the first FSS layer 1701. The term "operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of a radiation element (e.g., the low-band radiation element 222 or the high-band radiation element 1195). The spacing between the FSS layers (e.g., 1701 and 1702) can be about 1 / 10 - 1 / 2 (typically 1 / 4) of the operating wavelength and is related to the electrical length. For example, placing a material with a higher dielectric constant (DK) between them can allow for a smaller spacing.

[0136] In some embodiments, the first FSS1701 and the second FSS1702 can be located at a distance within the range of 1 / 10 wavelength to 1 / 2 wavelength of the operating wavelength in front of the high-band radiation element 1195.

[0137] Reference Figure 7 ,the base station antenna 100 may include at least a first FSS layer 1701, a second FSS layer 1702, and a third FSS layer 1703 stacked closely spaced in the front-back (Z) direction, and each FSS layer may include an array 171 of unit cells. Each of the FSS layers 1701, 1702, 1703 may be spaced apart from each other by about 1 / 10 - 1 / 2 of the operating wavelength, such as about 1 / 4 wavelength of the operating wavelength of the high-band radiation element 1195 behind the third FSS 1703 and / or the low-band radiation element 222 in front of the first FSS layer 1701. Using three or more FSS layers 1701, 1702, 1703 can facilitate a wider bandwidth and / or higher reflection at the low band. Using three or more stacked FSS layers can provide a larger / higher reflection at the low band.

[0138] Figure 6 and 7 Two or three FSS structures of Figure 21A 、 21B ) may be configured to have a passband (

[0139] Figure 8 ) for the mMIMO radiation element 1195, which includes at least some frequencies in the ranges such as: 3150 - 5000 MHz and 2200 - 4200 MHz and all sub-bands therebetween, such as 2490 - 2690 MHz, 3400 - 3980 MHz, and 2900 - 4000 MHz.

[0139] Figure 8 Shows the unit cells 171u of each of the first FSS layer 1701 and the second FSS layer 1702 aligned in the X and Y directions, where the second FSS layer 1702 is behind the first FSS layer 1701 (in the Z direction), the center 2171 of the front / first FSS layer 1701 is at substantially the same position as the center 2171 of the rear / second FSS layer 1702, and the linear segments 2172 of each of the FSS layers 1701, 1702 are also aligned such that the linear segment 2172 of the front FSS 1701 is at substantially the same X - Y position as the linear segment 2172 of the rear FSS 1702. Here, the term "substantially" means within + / - 10% of each other in the X and / or Y directions.

[0140] The inductor feature 21732 of the second FSS layer 1702 may be configured to have (a) different inductance value(s) from the inductor feature 21731 of the first FSS layer 1701. The inductor feature 21732 of the second FSS layer 1702 may have inductor features of different sizes and / or different shapes, shown as having protrusions 2173p that protrude laterally by a distance dx or longitudinally by a distance dy, further than the corresponding inductor feature 21731 of the first FSS layer 1701.

[0141] The inductor feature 2173 can be configured to have different inductance values, which can depend on the distance of the respective FSS layers 1701, 1702 from the front radome 100f and / or the rear radome 100r( Figure 2B ) or the distance from the radome 119 of the AAU 110( Figure 21A 、 21B ). The inductance value can also vary, for example, based on broadband operation when used for 5G operation, or based on whether it is positioned behind the low-band radiation element 222 or the mid-band radiation element 232, respectively( Figure 21A 、 21B ). The thickness and DK of the (multiple) radomes 111f and / or 119 can be key factors in selecting an appropriate inductance value.

[0142] The inductor feature 2173 can be formed with symmetric laterally extending protrusions 2173p on both sides 171s of the respective unit cell 171u and symmetric longitudinally extending protrusions 2173p on the other two sides 171s of the respective unit cell 171u, where the protrusions 2173p extend around and opposite to a virtual center line C / L that extends from and is aligned with the corresponding linear segment 2172. The inductor feature 2173 of each of the first FSS layer 1701 and the second FSS layer 1702 can extend a common distance starting from a distance spaced apart from the center 2171 to the perimeter 171p of the respective unit cell 171u.

[0143] Figure 9 Two adjacent unit cells 171u1, 171u2 of each stacked first FSS layer 1701 and second FSS layer 1702 are shown. As shown, the first inductor structure 21731a on the first FSS layer 1701 merges into the second inductor structure 21731b at the common perimeter side 171s shared by 171c. The second FSS layer 1702 also provides corresponding first inductor structures 21732a and second inductor structures 21732b that are connected at the common perimeter side 171s shared by the adjacent unit cells 171u1, 171u2. The first inductor structure 21732a and the second inductor structure 21732b of the second FSS layer 1702 have protrusions 2173p that are behind and aligned with the first inductor structure 21731a and the second inductor structure 21731b of the first FSS layer 1701 in the X, Y directions, but longitudinally extend beyond the boundaries of the corresponding protrusions 2173p on the first FSS layer 1701. The other three sides 171s of the respective unit cells 171u1 and 171u2 can have similarly connected inductor structures 2173.

[0144] Figure 10A Another embodiment of an exemplary unit cell 171u is shown. In this embodiment, the center 2171 is surrounded by a shaped pattern 2176 that is symmetric on four sides and has a curved perimeter 2176p that merges into four linear segments 2172 that are orthogonal to each other and then into an inductor structure 2173. The shaped pattern 2176 can be a box pattern 2176b having four corners 2176c.

[0145] Figure 10A Also shown is a first FSS layer 1701 in front of and above a second FSS layer 1702 having a corresponding aligned unit cell 171u. The shaped pattern 21762 around the center 2171 on the second FSS layer 1702 is aligned with the shaped pattern 21761 on the first FSS layer 1701 in the X-Y direction such that it is "hidden" by the shaped pattern 2176 on the first FSS layer 1701 in the view shown.

[0146] Figure 10B An alternative configuration of at least one of the FSS layers 170 having a unit cell 171u is shown, the unit cell having an inductor structure 2173 and a shaped (metal) pattern 2176p around the center 2171. In this embodiment, the shaped pattern 2176p is configured such that the box pattern 2176b is rotated 90 degrees from the Figure 10A orientation in, and the inductor structures are connected at the corresponding corners, where each of the four inductor structures 2173 merges into a different one of the four corners 2176c of the box pattern 2176b.

[0147] Referring Figure 10C , the unit cell 171u can be arranged to provide a broadband FSS, the equivalent circuit 1700 of which includes a corresponding capacitor 2273 in parallel with the corresponding inductor 2173, thereby forming three LC circuits 2275, two of the three LC circuits having a pair of inductors and a capacitor 2273 in parallel with each other, and the center LC circuit having a single LC circuit 2275 without a parallel inductor 2173a.

[0148] The circuit 1700 can provide a high-pass filter, and the inductance / inductor can be very small. Alternatively, the circuit 1700 can provide a low-pass filter, and the capacitor / capacitance can be very small. The inductance L and capacitance C can be calculated by SRF = 1 / 2π√LC. As is known to those skilled in the art, "SRF" means "self-resonant frequency". In antenna or circuit design, this frequency can be related to the middle / center frequency of the operating frequency band.

[0149] Figure 11Another embodiment of the exemplary unit cell 171u is shown. In this embodiment, four linear segments 2172 extend orthogonally from the center 2171 to each other and are again combined into an inductor structure 2173 having protrusions 2173p as discussed above with respect to other embodiments. In this embodiment, the inductor structure 2173 is located at a closer distance from the center 2171 and terminates before the outer peripheral side 171s, such that there are external linear segments 2178 extending from the inductor structure 2173 to the outer peripheral side 170s. In this embodiment, the inductor structures 2173 of adjacent unit cells 171u will be connected via the external linear segments 2178. Thus, in this embodiment, the four linear segments 2172 are internal linear segments, and one inductor structure 2173 can be located between each pair of external linear segments 2178 and internal linear segments 2172, respectively.

[0150] Figure 12 Another embodiment of the exemplary unit cell 171u is shown. In this embodiment, the inductor structures 2173 are located at intervals around the perimeter of the unit cell 171u. The perimeter 171p has linear segments 2172 that connect the spaced-apart inductor structures 2173. A major portion, such as 60 - 95%, of the surface area of the unit cell 171 in the X - Y direction (including the center 2171) can be open and / or without any metal or metal traces. The inductor structures 2173 have protrusions 2173p extending inward from the perimeter 171p. As shown, the linear segments 2172 stop or merge into each end 2173e of the inductor structure 2173 such that they do not extend longitudinally or laterally at the location of the inductor structure 2173.

[0151] Reference Figure 13 , for adjacent unit cells 171u1, 171u2, the linear segments 2172 can be arranged as a common linear segment 2172s at the common outer peripheral side 170s, and the corresponding inductor structures 21731, 21732 can protrude inward from the common linear segment 2172s. The common common side 170c is configured with two inductor structures 21731, 21732 that define a parallel inductor circuit 2200 thereat.

[0152] Adjusting the inductance provided by the inductor structure 2173 can provide good s - parameters for the operating frequency bands of various embodiments of the base station antenna 100.

[0153] The parallel inductor circuit 2200 can be configured to provide the same inductance as a single inductor 2173 for the unit cell 171u. For the unit cell 171u disposed in a metal substrate or provided by a larger metal pattern, the reflection in the low frequency band can be greater / higher, but the passband s-parameters can be slightly reduced relative to the narrow metal traces on the dielectric layer.

[0154] Figure 14 A circuit schematic showing an exemplary current direction based on the radiation projected in the Z direction ( Figure 15 ) through the FSS layer 170 with the unit cell 171u is shown. The capacitance is very small.

[0155] The unit cell 171u can be arranged to provide an equivalent circuit 1700 as shown in Figure 16A (a vertical equivalent circuit with a capacitor 2273 in series with an inductor 2173) and an equivalent circuit as shown in Figure 16B (a horizontal equivalent circuit between nodes a and b as shown in Figure 14 , where the capacitor 2273 is in parallel with the inductor 2173, thus forming an LC circuit). In Figure 16A , the circuit 1700 can provide a high-pass filter, and the inductance / inductor is very small. In Figure 16B , the circuit 1700 can provide a low-pass filter, and the capacitor / capacitance is very small. The inductance L and capacitance C can be calculated by SRF = 1 / 2π√LC. As is known to those skilled in the art, "SRF" means "self-resonant frequency". In antenna or circuit design, this frequency can be related to the middle / center frequency of the operating frequency band.

[0156] In some embodiments, the unit cell 171 of one or more of the FSS layers 1701, 1702, 1703 can be configured to provide an equivalent circuit of a high-pass filter in the vertical and horizontal directions, and the inductor structure 2173 can provide a disconnected high-frequency band current space. High-frequency band current can pass through the inductor, while the low frequency band can be rejected.

[0157] Figure 16C A circuit 1700 is shown, i.e., the simulated broadband FSS response (db) of the horizontal equivalent circuit H ( Figure 16B ) and the vertical equivalent circuit V ( Figure 16A ) with respect to frequency (GHz), such as the m1 - m4 parameters.

[0158] Figure 16D The simulated response of a basic sample LC circuit acting as a reference is shown. The response frequency is f0 (about 2.5 GHz), m2 is the start of the passband, and m4 is the end of the stopband.

[0159] Now turning to Figure 17A, the (equivalent unit cell) circuit 1700 of FSS 170 may include a transmission (“TX”) line segment 2373, which may be electrically coupled to an inductor 2173. As shown, the inductor 2173 and the capacitor 2273 form an LC circuit. The transmission line segment 2373 is in parallel with the LC circuit 2275. The TX line segment 2373 may have a width dimension W, which may optionally be less than the length dimension L. The TX line segment 2373 may be wider than the microstrip trace segments 2375 at its opposite ends. The length L may be approximately half the wavelength of the second response point f2, and the width W may be any value as this is equivalent to the L and C values. Depending on the target design, the width W may be configured (equal to adjusting L / C) to achieve a high Q value and / or a low Q value.

[0160] In some specific embodiments, the TX line segment 2373 may have a width dimension W in the range of 0.02 mm to 0.2 mm. In some particular embodiments, in some embodiments, the length dimension L may be in the range of 10 - 30 mm, for example, about 22.6 mm.

[0161] In some embodiments, the length dimension L of the TX line segment 2373 may be configured such that the signal passing through the TX line segment undergoes a 180 - degree phase shift at a defined frequency f2. In some embodiments, the defined frequency f2 may be in the high - frequency band range, for example, in the range between 3.5 and 6.5 GHz.

[0162] Figure 17B is shown Figure 17A a simulation response curve graph of the broadband FSS grid of the equivalent circuit 1700 shown in, i.e., a graph of frequency (GHz) versus decibels, having f0 and f2 and exemplary m1, m2, and m4 parameters. By adding an additional TX line segment 2373 to the circuit 1700, a second response frequency point occurs, and the total bandwidth can be extended. f2 is the second response frequency point.

[0163] Figure 18A shows another exemplary equivalent circuit 1700 having a first transmission line segment 23731 and a second transmission line segment 23732 coupled to the LC circuit 2275, one transmission line segment above and in parallel with the LC circuit 2375, and one transmission line segment below and in parallel with the LC circuit 2275. The two transmission line segments 23731, 23732 may have a length dimension L, which in some embodiments may be shorter than Figure 17AThe length dimension shown, for example, is about 17 mm. The ultra-wideband FSS equivalent circuit 1700 can be configured such that the phase increases: PH2 = arc tan(X / R), where X is a fixed imaginary number and R is a real number in the series circuit. By adding the second TX line segment 2373, the Q value of the circuit 1700 can become lower and the bandwidth of the bandpass can be extended.

[0164] Figure 18B Shows Figure 18A The simulation response curve graph of the broadband FSS grid of the equivalent circuit 1700 shown in, that is, the graph of frequency (GHz) versus decibels, with f0 and f2 and exemplary m1, m2, m3, and m4 parameters. As shown, f0 can be in the range of 2 - 3 GHz, for example, about 2.5 GHz, while f2 can be in the range of 4.5 - 6.5 GHz, for example, the minimum value of about 5.5 GHz.

[0165] Figure 19A Shows another exemplary equivalent circuit 1700 having a first transmission line segment 23731 and a second transmission line segment 23732 serially coupled to a plurality of inductors 2173 (shown as a first inductor 21731, a second inductor 21732, and a third inductor 21733). The second (middle) inductor 21732 can have a larger inductance than the end inductors 21731, 21733. The unit cell (equivalent) circuit 1700 can include a capacitor 2273. The circuit 1700 can include a second capacitor 22732 in parallel with the first capacitor 22731. Both the first transmission line segment 23731 and the second transmission line segment 23732 can be on the common side (both shown above) and in parallel with the second capacitor 22732.

[0166] Figure 19C Shows Figure 19A The simulation response reference response of the equivalent circuit 1700 shown in, that is, frequency (GHz) versus decibels, with f0 and f2 and exemplary m2, m4, and m6 parameters. As shown, f0 can be in the range of 2 - 3 GHz, for example, about 2.5 GHz, while f2 can be in the range of 3.5 - 5 GHz, shown as about 4.5 GHz.

[0167] Figure 19B Is a schematic diagram of a plurality of unit cells 171u of the grid reflector 170, whereby at least some of the unit cells 171u can be configured to have Figure 19A The equivalent circuit 1700 shown in.

[0168] Figure 20AAnother exemplary equivalent circuit 1700 is shown having a first transmission line segment 23731 and a second transmission line segment 23732 coupled to a plurality of inductors 2173. The inductors 2173 may be in series with a first capacitor 22731 therebetween. The circuit 1700 may include a second capacitor 22732 in parallel with the first capacitor 22731. The second capacitor 22732 may have a larger capacitance than the first capacitor 22731. Both the first transmission line segment 23731 and the second transmission line segment 23732 may be on a common side (both shown above) and in parallel with the capacitor 2273.

[0169] Figure 20C is shown Figure 20A The simulation response of the equivalent circuit 1700 shown in, i.e., frequency (GHz) versus decibels, has f0 and f2 and exemplary m2, m4, and m6 parameters. As shown, f0 may be in the range of 2 - 3 GHz, e.g., about 2.5 GHz, while f2 may be in the range of 3.5 - 5 GHz, shown as about 4.5 GHz.

[0170] Figure 20B is a schematic diagram of a plurality of unit cells 171u of a grid reflector 170, whereby at least some of the unit cells 171u may be configured to have Figure 20A the equivalent circuit 1700 shown in.

[0171] Figure 21A Another exemplary equivalent circuit 1700 is shown having a first transmission line segment 23731 and a second transmission line segment 23732 coupled to a plurality of inductors 2173. In this embodiment, Figure 19A the inductors of Figure 20A and the capacitors of

[0172] Figure 21D is shown Figure 21AThe simulated response curve graph of the equivalent circuit 1700 shown in [the figure], that is, the graph of frequency (GHz) versus decibels, has f0 and f2 and exemplary m1, m2, m4, and m6 parameters. As shown, f0 can be in the range of 2 - 3 GHz, for example, about 2.5 GHz, while f2 can be greater than f0 and in the range of 3.5 - 5 GHz, shown as about 4.5 GHz.

[0173] Figure 21B is a schematic diagram of a plurality of unit cells 171u of the grid reflector 170, whereby at least some of the unit cells 171u can be configured to have Figure 21A the equivalent circuit 1700 shown in [the figure]. A single-layer copper printed circuit board can provide the unit cells 171u. Figure 21C is Figure 21B an enlarged portion of the unit cell shown in [the figure], which shows parallel adjacent traces 2373L forming part of the unit cell 171u. The parallel lines 2373L can be used for the TX line segments 2373 and can be configured such that one layer of copper or other conductive metal can be used for the unit cell 171u.

[0174] Figure 22A shows another example of a broadband FSS using a double-layer FSS configuration that can be electrically coupled and stacked in the front - to - back direction. Each layer 1701, 1702 includes cooperating components that together with the components form the equivalent circuit 1700. Each layer 1701, 1702 includes unit cells 171u, where a first transmission line segment 23731 and a second transmission line segment 23732 are coupled to a plurality of inductors 2173. Each layer 1701, 1702 can include unit cells 171u having the same equivalent circuit 1700 configuration. In this embodiment, as discussed with respect to Figure 21A a first inductor 21731 is attached to the first ends of the TX line segments 23731, 23732, and a second inductor 21732 is attached to the opposite second ends of the TX line segments 23731, 23732. The circuit 1700 can include a capacitor 2273 coupled to the first inductor and the second inductor. The second capacitor 22732 can have a larger capacitance than the first capacitor 22731. Both the first transmission line segment 23731 and the second transmission line segment 23732 can be on a common side (both shown above) and in parallel with the capacitor 2273.

[0175] Figure 22C shows Figure 22A the simulated response curve graph of the equivalent circuit 1700 shown in [the figure], that is, the graph of frequency (GHz) versus decibels, having f0 and exemplary m1, m2, and m6 parameters. As shown, f0 can be in the range of 2 - 3 GHz, for example, about 2.5 GHz.

[0176] Figure 22B is a schematic diagram of a plurality of unit cells 171u of the first layer 1701 and the second layer 1702 of a grid reflector, whereby at least some of the unit cells 171u in each layer can be configured to have Figure 22A the equivalent circuit 1700 shown in

[0177] Figure 23A Another example of a broadband FSS using a double-layer FSS configuration that can be electrically coupled and stacked in the front-to-back direction is shown. Each layer 1701, 1702 includes components that form an equivalent circuit 1700. Each layer 1701, 1702 includes unit cells 171u, where a first transmission line segment 23731 and a second transmission line segment 23732 are coupled to a plurality of inductors 2173. Each layer 1701, 1702 can include unit cells 171u having different configurations of the equivalent circuit 1700. In this embodiment, the first layer 1701 includes an equivalent circuit 1700, where a first inductor 21731 is attached to the first ends of the TX line segments 23731, 23732, and a second inductor 21732 is attached to the opposite second ends of the TX line segments 23731, 23732. The circuit 1700 can include a capacitor 2273 coupled to the first inductor 21731 and the second inductor 21732. The second capacitor 22732 can have a larger capacitance than the first capacitor 22731. Both the first transmission line segment 23731 and the second transmission line segment 23732 can be on a common side (both shown above) and in parallel with the capacitor 2273. The second layer 1702 can have an equivalent circuit 1700 that includes an LC circuit 2275 coupled to the equivalent circuit provided by the first layer 1701.

[0178] Figure 23C shows Figure 23A a simulation response curve graph of the equivalent circuit 1700 shown in , i.e., a graph of frequency (GHz) versus decibels, with f0 and exemplary m1, m2, and m6 parameters. As shown, f0 can be in the range of 2 - 3 GHz, for example, about 2.5 GHz, while f2 can be larger, for example, in the range of about 3.5 - 5 GHz, shown as about 4.5 GHz.

[0179] Figure 23B is a schematic diagram of unit cells 171u of the first layer 1701 and the second layer 1702 of a grid reflector tightly stacked in the Z or front-to-back direction, whereby at least some of the unit cells 171u in each layer can cooperate to form Figure 23A the equivalent circuit 1700 shown in

[0180] Figure 24AAnother example of a broadband FSS using a double - layer FSS configuration is shown. Each grid FSS layer 1701, 1702 includes a unit cell 171u that forms components of at least one equivalent circuit 1700. The double - layer FSS configuration can be electrically coupled and stacked in the front - to - back direction behind the front radome 111f of the base station antenna 100( Figure 2A ).

[0181] Figure 24B is Figure 24A a front view of the top layer 1701 shown in, which shows that the grid layer 1701 can have cut - out regions 1170 of material that extend within and / or around the respective unit cells 171u.

[0182] In some specific embodiments, one or both of the layers 1701, 1702 can optionally be formed of a low - dielectric - constant (e.g., DK in the range of 1 - 4, more typically 2 - 4) material.

[0183] The main material of the (multiple) substrates providing the multiple unit cells 171u can optionally include a low - dielectric - constant (DK) material. To change the LC values in the equivalent circuit 1700, this can be done by changing the size of the metal in the main material and the size of the cut - out regions, and can include high - DK material characteristics.

[0184] Figure 25A An equivalent circuit 1700 is shown, which has an inductor structure 2173 and a capacitor 2273 that form an LC circuit 2275. Figure 25B A metamaterial and / or surface 1171 is shown, which can be configured to perform Figure 25A the circuit 1700 shown in. Figure 25C A dielectric material is shown that is selected to perform Figure 25A at least a part of the circuit 1700 shown in. Figure 25A The L / C values of the inductor 2173 structure and the capacitor 2273 can be selected based on operating requirements and / or implementation (e.g., Figure 24A the FSS layers 1701, 1702 shown in).

[0185] The dielectric material does not need to be a low - DK material. For example, if Figure 24A the configuration of the FSS layers 1701, 1702 shown in, for example, requires a different L / C, and this L / C can be provided by a high - DK dielectric material, then the high - DK dielectric material can be used for Figure 24A the FSS layers shown in.

[0186] It should be noted that if the DK is too high to obtain or is expensive, then a metasurface option can be used, such as Figure 25BAs shown. The metamaterial 1171 may include adjacent segments separated by cutout segments that provide a very small capacitance 2273, and the metamaterial 1171 may provide inductance.

[0187] It should be noted that although the unit cell 171u is shown in some of the figures as having a square perimeter, other shapes may be used. Different "sides" may be provided based on the shape. For example, a circular unit cell 171u may have circumferentially spaced inductor structures that extend around a perimeter extending radially from a center. The unit cell 171u may have various shapes, such as triangular, rectangular, rhombic, pentagonal, hexagonal, circular, elliptical, etc., and combinations of different shapes for different unit cells.

[0188] It should be noted that depending on the application / use, larger inductors or inductors with larger inductance may be provided on the front FSS layer 1701 or the back FSS layer 1702. Additionally, the array 171 of unit cells may be provided with unit cells 171u of different shapes or densities at different locations (see Figure 26 , 27 , 28).

[0189] Reference Figure 26 , 27 and 28, the grid reflector 170 may be configured such that there are different densities of unit cells 171u at different locations. In some embodiments, the grid reflector 170 may be configured such that the unit cells 171u may be asymmetric with respect to one or more axes to, for example, improve cross-polarization performance.

[0190] Figure 26 It is shown that the array 171 of unit cells 171u may be arranged with a greater density of unit cells 171u at the left and right portions 170r, 170l relative to the inner portion 170m. Figure 26 It is also shown that the unit cells 171 located at the inner portion 170m of the grid reflector 170 may have a greater surface area, height, and / or width than the unit cells 171u located at the left and right portions 170r, 170l, shown as having a common height dimension and different width dimensions and having a greater central space 172.

[0191] Figure 27 It is shown that there is a greater density of unit cells 171 at the inner portion 170m of the grid reflector 170 relative to the unit cells 171u at the right portion 170r and / or the left portion 170l. Figure 27It is also shown that the unit cells 171 located at the right and left portions 170r, 170l may have a larger surface area, height, and / or width than the unit cells 171 located at the inner portion 170m, shown as a common height and a larger width and having a larger central space 172.

[0192] Figure 28 It is shown that the frequency-selective surface of the grid reflector 170 may have unit cells 171u of different shapes in different regions. In some embodiments, the inner portion 170m of the grid reflector 170 may include square unit cells 171u, while the right 170r and left 170l may each have hexagonal unit cells 171u respectively. These unit cells 171u of different shapes may be provided on one grid reflector or on the first grid reflector 1701 and the second grid reflector 1702 stacked in the front-back (Z) direction. Figure 29A It is shown that the hexagonal shape of the unit cell 171u may be a solid (metal) patch, while Figure 29B It is shown that the hexagonal shape of the unit cell 171u may be arranged as a hexagonal ring around an open center or a center of a different (non-conductive) material.

[0193] Thus, as Figure 26 、 27 and as shown in 28, the first grid reflector 1701 may have an array of unit cells 171, wherein a first subset of the unit cells 171u is tuned to block and / or reflect RF energy in a first frequency band while allowing RF energy in a second frequency band to propagate through the first grid reflector, and a second subset of the unit cells 171u is tuned to block and / or reflect RF energy in the first frequency band and RF energy in a third frequency band. The third frequency band includes frequencies between the first frequency band and the second frequency band.

[0194] The first subset 171a of the unit cells 171u may be located at the upper portion of the base station antenna 100. The second subset 171b of the unit cells 171u may include unit cells below and / or to the right and left of the first subset 171a of the unit cells 171u.

[0195] The first subset 171a of the unit cells 171 may be located behind the low-band radiation element 222 and in front of the high-band radiation element 1195 (e.g., mMIMO array) and / or the dual-band radiation element. The second subset 171b of the unit cells 171 may be located behind the mid-band radiation element 232. The first frequency band may be a low frequency band, the second frequency band may be a high frequency band, and the third frequency band may be a mid frequency band, having at least some frequencies between the first frequency and the second frequency.

[0196] A first subset of the unit cells 171u may be positioned at an upper portion of the base station antenna 100. A second subset 171b of the unit cells 171 may include unit cells below and / or to the right and left of the first subset 171a of the unit cells 171. Some of the unit cells 171u in the second subset 171b of the unit cells 171 may be to the left and / or right of the first subset 171a of the unit cells.

[0197] The first subset 171a of the unit cells 171 may be located behind the low-band radiation element 222 and in front of the high-band radiation element 1195 (e.g., mMIMO array). The second subset 171b of the unit cells 171 may be located behind the mid-band radiation element 232.

[0198] The first FSS layer / first grid reflector 1701 may be configured to merge into or attach to the longitudinally extending right and left sides 214s of the (substantially solid) surface of the main reflector 214 at one or more locations, for example, along the laterally extending outer side. As discussed above, the grid reflector 170 may be configured to have different unit cell configurations and / or sizes at different locations.

[0199] In some embodiments, the first FSS layer / first grid reflector 1701 of the passive antenna assembly 190 may be configured to act as a high-pass filter that substantially allows low-band energy to be completely reflected while allowing higher-band energy (e.g., about 3.5 GHz or higher) to pass through, generally substantially completely.

[0200] The first FSS layer 1701 and the second FSS layer 1702 may be transparent or invisible to higher-band energy and may cooperate to provide a suitable out-of-band rejection response that can be achieved.

[0201] Now turning Figure 30A 、 30B , an exemplary passive antenna assembly 190 is shown. The first FSS layer / first grid reflector 1701 may be merged into the longitudinally and laterally extending main reflector 214. The main reflector 214 may have a greater longitudinal length than the longitudinal length of the first grid reflector 1701. The main reflector 214 may have a solid reflecting surface for antenna elements located in front of the main reflector 214 and may be located above the operating components 314 (e.g., filters, tilt regulators, etc.).

[0202] In some embodiments, the first grid reflector 1701 may be located at a distance within the range of 1 / 8 wavelength to 1 / 4 wavelength of the operating wavelength behind the low-band dipole 222. As discussed above, the term "operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of a radiating element (e.g., the low-band radiating element 222). In some embodiments, the first grid reflector 1701 may be located at a distance within the range of 1 / 10 wavelength to 1 / 2 wavelength of the operating wavelength in front of the high-band radiating element 1195. For example, in certain specific embodiments, the first grid reflector 1701 may be located at a physical distance of 0.25 inches and 2 inches from the ground plane or reflector 1172 behind the mMIMO array of the radiating element 1195 of the active antenna module 110( Figure 31A , 31B ). Other placement positions may be used.

[0203] In some embodiments, the ground plane or reflector 1172 of the active antenna module 110 may be electrically coupled to the first grid reflector 1701 and / or the main reflector 214 of the base station antenna 100, e.g., by current coupling and / or capacitive coupling. In other embodiments, the ground plane or reflector 1172 of the active antenna module 110 is not electrically coupled to the first grid reflector 1701 and / or the main reflector 214.

[0204] Referring Figure 30A , the first grid reflector 1701 may have a longitudinal extent "L" and a lateral extent "W". The longitudinal extent L may extend a distance greater than the lateral extent W. The longitudinal extent L may be less than the lateral extent W. The first grid reflector 1701 has a front side 170f facing the front side 100f of the housing 100h / dome 111.

[0205] The antenna assembly 190 includes multiple arrays of radiating elements, typically arranged in six columns, where the radiating elements extend forward from the front side 170f of the first FSS layer 1701, and some columns of the radiating elements continue to extend in front of the main reflector 214. Each array of the radiating elements of the antenna assembly 190 may include radiating elements 222 configured to operate in a first frequency band and radiating elements 232 configured to operate in a second frequency band. Other arrays of the radiating elements may include radiating elements configured to operate in the second frequency band or the third frequency band. The first frequency band, the second frequency band, and the third frequency band may be different frequency bands (although they may overlap). In some embodiments, the low-band antenna elements 222 having dipole arms may be located in front of the grid reflector 170, typically along the right and left portions 170s of the grid reflector 170 and / or the main reflector side 214s.

[0206] In some embodiments, the first FSS layer / mesh reflector 1701 and the main reflector 214 can be integrally formed as a one-piece (sheet-like) metal body. Alternatively, the first mesh reflector 1701 and the main reflector 214 can be provided as separate components that are directly or indirectly attached and electrically coupled together to provide a common electrical ground. Both the first mesh reflector 1701 and the main reflector 214 can be metal sheets of the same or different thicknesses. The first mesh reflector 1701 can be provided as a printed circuit on a dielectric substrate, and the main reflector 214 can be a metal sheet.

[0207] In some embodiments, the first FSS layer and the second FSS layer 1701, 1702 can each be provided as a printed circuit board, where conductive traces form an array 171 of unit cells. The first mesh reflector and / or the second mesh reflector 1701, 1702 can be provided as a flexible circuit board having unit cells 171u. The first mesh reflector and / or the second mesh reflector 1701, 1702 can be provided as a non-metallic substrate where metallized traces form unit cells 171u.

[0208] Some of the radiating elements (discussed below) of the antenna 100 can be mounted to extend forward from the main reflector 214, and if dipole-based radiating elements are used, the dipole radiators of these radiating elements can be mounted approximately 1 / 4 of the wavelength of the operating frequency of each radiating element in front of the main reflector 214. The main reflector 214 can be used as a reflector and a ground plane for the radiating elements mounted thereon of the base station antenna 100.

[0209] Still referring to Figure 30A 、 30B , the passive antenna assembly 190 of the base station antenna 100 can include one or more arrays 220 of low-band radiating elements 222, one or more arrays 230 of first intermediate-band radiating elements 232, one or more arrays 240 of second intermediate-band radiating elements 242, and optionally one or more arrays 250 of high-band radiating elements 252. The radiating elements 222, 232, 242, 252, 1195 can each be a dual-polarized radiating element. Further details of the radiating elements can be found in WO2019 / 236203 and WO2020 / 072880, the contents of which are incorporated herein by reference as if recited in full herein. Some of the high-band radiating elements such as the radiating element 1195 can be provided as mMIMO antenna arrays and can be provided in the active antenna module 110 instead of in the housing 100h of the base station antenna 100.

[0210] The low-band radiation elements 222 can be mounted to extend forward from the main or primary reflector 214 and the first FSS layer 1701, and can be mounted in two columns to form two linear arrays 220 of the low-band radiation elements 222. In some embodiments, each low-band linear array 220 can extend along substantially the entire length of the antenna 100.

[0211] The low-band radiation elements 222 can be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band can include the 617 - 960 MHz frequency range or a portion thereof (e.g., the 617 - 896 MHz band, the 696 - 960 MHz band, etc.). The low-band linear arrays 220 can be used or not used to transmit and receive signals in the same portion of the first frequency band. For example, in some embodiments, the low-band radiation elements 222 in the first linear array 220 can be used to transmit and receive signals in the 700 MHz band, and the low-band radiation elements 222 in the second linear array 220 can be used to transmit and receive signals in the 800 MHz band. In other embodiments, the low-band radiation elements 222 in both the first linear array 220-1 and the second linear array 220-2 can be used to transmit and receive signals in the 700 MHz (or 800 MHz) band.

[0212] The first intermediate-band radiation elements 232 can be similarly mounted to extend forward from the main reflector 214 and / or the first FSS layer 1701, and can be mounted in multiple columns to form a linear array 230 of the first intermediate-band radiation elements 232. The linear array 230 of the intermediate-band radiation elements 232 can extend along the respective side edges of the first FSS layer 1701 and / or the main reflector 214. The first intermediate-band radiation elements 232 can be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band can include the 1427 - 2690 MHz frequency range or a portion thereof (e.g., the 1710 - 2200 MHz band, the 2300 - 2690 MHz band, etc.). In the depicted embodiment, the first intermediate-band radiation elements 232 are configured to transmit and receive signals in the lower portion of the second frequency band (e.g., some or all of the 1427 - 2200 MHz band). The linear array 230 of the first intermediate-band radiation elements 232 can be configured to transmit and receive signals in the same portion or different portions of the second frequency band.

[0213] The second intermediate-frequency band radiating elements 242 may be mounted in multiple columns to form a linear array of the second intermediate-frequency band radiating elements 242. The second intermediate-frequency band radiating elements 242 may be configured to transmit and receive signals in a second frequency band. In the depicted embodiment, the second intermediate-frequency band radiating elements 242 are configured to transmit and receive signals in the upper portion of the second frequency band (e.g., some or all of the 2300 - 2700 MHz frequency band). In the depicted embodiment, the second intermediate-frequency band radiating elements 242 may have a different design from the first intermediate-frequency band radiating elements 232.

[0214] The high-frequency band radiating elements 252 and / or 1195 may be mounted in columns in the upper inner or central portion of the antenna 100 to form a multi-column (e.g., four or eight columns) array 250 of the high-frequency band radiating elements 252 and / or 1195. The high-frequency band radiating element 1195 may be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may include the 3300 - 4200 MHz frequency range or a portion thereof.

[0215] In the depicted embodiment, the array 220 of the low-frequency band radiating elements 222, the array 230 of the first intermediate-frequency band radiating elements 232, and the array of the second intermediate-frequency band radiating elements 242 are all part of the passive antenna assembly 190, while the array 250 of the high-frequency band radiating elements 1195 is part of the active antenna module 110. It should be understood that in other embodiments, the types of arrays included in the passive antenna assembly 190 and / or the active antenna module 110 may vary.

[0216] It will also be recognized that the number of linear arrays of the low-frequency band, intermediate-frequency band, and high-frequency band radiating elements may be different from that shown in the figures. For example, the number of linear arrays of each type of radiating element may be different from that shown, some types of linear arrays may be omitted and / or other types of arrays may be added, the number of radiating elements in each array may be different from that shown, and / or the arrays may be arranged differently. As a specific example, two linear arrays of the second intermediate-frequency band radiating elements 242 may be replaced with four linear arrays of ultra-high-frequency band radiating elements that transmit and receive signals in the 5 GHz frequency band.

[0217] At least some of the low-frequency band radiating elements 222 and the intermediate-frequency band radiating elements 232, 242 may each be mounted to extend forward from the first FSS layer 1701 or the main reflector 214 and / or extend from the first FSS layer or the main reflector.

[0218] Each array 220 of the low-band radiation elements 222 can be used to form a pair of antenna beams, i.e., one antenna beam for each of the two polarizations, and the dual-polarization radiation elements are designed to transmit and receive RF signals at the two polarizations. Similarly, each array 230 of the first mid-band radiation elements 232 and each array of the second mid-band radiation elements 242 can be configured to form a pair of antenna beams, i.e., one antenna beam for each of the two polarizations, and the dual-polarization radiation elements are designed to transmit and receive RF signals at the two polarizations. Each linear array can be configured to serve a sector of a base station. For example, each linear array 220, 230 can be configured to provide coverage of approximately 120° in the azimuth plane, such that the base station antenna 100 can be used as a sector antenna of a three-sector base station. Of course, it will be appreciated that the linear arrays can be configured to provide coverage at different azimuth beam widths. Although all of the radiation elements 222, 232, 242, 252, 1195 can be dual-polarization radiation elements in the depicted embodiment, it should be appreciated that in other embodiments, some or all of the dual-polarization radiation elements can be replaced with single-polarization radiation elements. It should also be appreciated that although the radiation elements are shown as dipole radiation elements in the depicted embodiment, other types of radiation elements, such as, for example, patch radiation elements, can be used in other embodiments.

[0219] Some or all of the radiation elements 222, 232, 242, 252, 1195 can be mounted on a feed board that couples RF signals in and out of the respective radiation elements 222, 232, 242, 252, 1195, with one or more radiation elements 222, 232, 242, 252, 1195 mounted on each feed board. Cables (not shown) and / or connectors can be used to connect each feed board to other components of the antenna 100, such as, for example, a duplexer, a phase shifter, a calibration board, etc.

[0220] An RF connector or "port" 140 ( Figure 2A ) can be mounted in the bottom end cap 130, and this RF connector or "port" is used to couple RF signals from an external remote radio unit (not shown) to the arrays of the passive antenna assembly 190. Two RF ports can be provided for each array, i.e., a first RF port 140 and a second RF port 140, where the first RF port couples a first polarization RF signal between the remote radio unit and the array, and the second RF port couples a second polarization RF signal between the remote radio unit and the array. Since the radiation elements 222, 232, 242 can be slant crossed dipole radiation elements, the first polarization and the second polarization can be -45° polarization and +45° polarization.

[0221] The phase shifter can be connected to the RF port 140. The phase shifter can be implemented as, for example, a brush arc phase shifter, such as the phase shifter disclosed in U.S. Patent No. 7,907,096 to Timofeev, the disclosure of which is incorporated herein by reference in its entirety. A mechanical linkage can be coupled to a RET actuator (not shown). The RET actuator can apply a force to the mechanical linkage, which in turn adjusts a movable element on the phase shifter so as to electronically adjust the downtilt angle of one or more generated antenna beams in a low frequency band or a medium frequency band linear array.

[0222] It should be noted that a multi-connector RF port (also referred to as a "cluster" connector) can be used instead of the separate RF port 140. A suitable cluster connector is disclosed in U.S. Patent Application Serial No. 16 / 375,530 filed on April 4, 2019, the entire content of which is incorporated herein by reference.

[0223] The radiating element 220 can be a dipole element configured to operate in some or all of the 617 - 960 MHz frequency band. A feeding circuit including a hook balun can be provided on the feeding handle 221( Figure 30B ). Further discussion of an exemplary antenna element including the antenna element (including the feeding handle) can be found in U.S. Patent Application Serial No. 17 / 205,122, the content of which is incorporated herein by reference as if set forth in full herein.

[0224] Now turning to Figure 31A 、 31B, showing an exemplary active antenna module 110. The active antenna module 110 may include a RRU (Remote Radio Unit) unit 1120 having radio circuitry. The active antenna module 110 may also include a filter and a calibration printed circuit board assembly (not shown), and an antenna assembly 1190 including a reflector or ground plane of a printed circuit board 1172 behind the radiating element 1195. The antenna assembly 1190 may also include a phase shifter (not shown), which may alternatively be part of the filter and calibration assembly. The radiating element 1195 may be arranged as a massive MIMO array. The RRU unit 1120 is a radio unit that typically includes radio circuitry for converting base station digital transmissions into analog RF signals (and vice versa). One or more of the radio unit or RRU unit 1120, the antenna assembly 1190, or the filter and calibration assembly may be provided as separate subunits that are attachable (stackable). The RRU unit 1120 and the antenna assembly 1190 may be provided as an integrated unit, optionally further including a calibration assembly 1180. In the case of being configured as subunits, different subunits may be provided by an OEM or a cellular service provider while still using the common base station antenna housing 100h and its passive antenna assembly 190. In other embodiments, the radio circuitry may be provided as a single integrated unit together with the antenna assembly.

[0225] Figure 31A It is shown that the rear portion 100r of the base station antenna 100 may have a flat surface, and the active antenna assembly 1190 may be configured to face the rear portion 100r, with the radome 119, 100r therebetween, and the first FSS layer and the second FSS layer 1701, 1702 in front of the radiating element 1195. Figure 21B It is shown that the rear portion 100r of the base station antenna 100 may have a recessed section 102 and be sized to receive the radome 119 of the active antenna unit 110. Again, the radiating element 1195 is behind the FSS layers 1701, 1702 and faces the FSS layers.

[0226] Figure 32A - 32F An additional exemplary embodiment showing stacked FSS layers 1701, 1702 spaced apart in the front-to-rear direction of the base station antenna 100 is shown. The array of radiating elements 1195 may be positioned behind the first FSS layer 1701 and the second FSS layer 1702, typically in the active antenna module 110. The array of radiating elements 1195 may include an mMIMO array of radiating elements as discussed above herein.

[0227] An array of radiating elements can be provided as dual - band radiating elements 1195d, where the first - column radiating elements in the first column project forward by a first distance and operate in a first frequency band, and the second - column radiating elements in the second column project forward by a smaller distance than the first column and operate in a second frequency band, and the unit cell in front of the first column can have a different configuration from the unit cell in front of the second - column radiating elements( Figure 32G ).

[0228] Reference Figure 32C 、 32D 、32E and 32F, the first FSS layer 1701 can include a plurality of spaced - apart cuts 1201. The feed plate 1200 can extend across / along these cuts 1201, and the feed handle 222f can connect the radiating element 222 to the feed plate 1200. In some embodiments, the feed plate 1200 can be located behind the main front surface 170f of the reflector 1701 and can include a conductive (e.g., copper - ground - plane - patterned surface / circuit). The radiating element 222 can be provided in different configurations and is not limited to the configuration shown.

[0229] Figure 32A 、 32F 、32G shows that at least one of the first FSS layer 1701 and the second FSS layer 1702 can have a forward / backward - extending portion having unit cells 171u that define at least a part of the sidewall 170w. The corresponding sidewall 170w can be metallic or provided as a printed circuit board or a combination thereof. The sidewall 170w can be a curved portion of one or more of the first FSS layer 1701 and the second FSS layer 1702. The sidewall 170w can provide structural support for the reflector 170 and / or the radiating element 222 mounted thereon. The sidewall 170w can also or alternatively be configured to improve the radiation pattern provided by one or more of the radiating elements 222 and / or the radiating element 1195 in front of and / or behind the reflector 1701, 1702.

[0230] The first / front FSS layer 1701 can be in a common plane with the main reflector 214 (front - to - back position aligned with the main reflector 214).

[0231] One or both of the first FSS 1701 layer and the second FSS layer 1702 can be configured such that the grid pattern extends across its entire lateral extent. In other embodiments, the grid pattern can be arranged / terminated at or coupled to the feed plate 1200 or its solid - metal surface.

[0232] Figure 32B 、 32EIt is shown that the first FSS layer 1701 and the second FSS layer 1702 can be set to the non-bending side. For example, one or both of the FSS layers 1701, 1702 can be coupled to an internal mounting structure, such as lateral extensions and / or longitudinal rails, to position them in alignment at an appropriate position in the base station antenna 100. One or both of the first FSS layer 1701 and the second FSS layer 1702 can be coupled to the surface of the radome or housing provided by the base station antenna 100.

[0233] Reference Figure 32A 、 32F and 32G, the sidewall 170w can be solid metal (e.g., a solid metal sheet), or can have apertures 170a or cuts between strip segments extending behind and / or in front of the front main surface 170f of the grid reflector 170.

[0234] Also as Figure 32G shown, the sidewall 170w can extend in front of and behind the front surface 170f of the first FSS layer 1701 and / or the second FSS layer 1702, shown as extending in front of and behind the front / first FSS layer 1701 and orthogonal thereto.

[0235] At least a portion of the sidewall 170w can be provided by a metal grid or otherwise configured to provide an isolation surface / wall or FSS, such as metallic, metallized, or set as a frequency selective surface / substrate.

[0236] As Figure 32G shown, the (plural) sidewalls 170w can have a front segment 170wf extending forward in front of the reflector 170f. The (plural) sidewalls 170w can also have a rear / rear segment 170wb that extends behind the front segment, wherein the front portion of the reflector extends laterally between the rear / rear segment and the front segment. The front segment 170wf can have a different configuration from the rear segment 170wb. In some embodiments, the front segment 170wf can be solid metal or formed by an FSS. The rear / rear segment 170wb can be solid and have apertures 170a and / or a grid pattern 171.

[0237] Figure 32A 、 32B and 32E show a base station antenna 100 including three stacked FSS layers 1701, 1702, 1703.

[0238] The first FSS layer 1701 and the second FSS layer 1702 can be spaced apart by a distance “h” defined by the front-to-rear dimension. In some embodiments, the distance “h” can be in the range of 5 - 50 mm, such as about 20 mm.

[0239] The distance "h" may correspond to a distance of 0.05 - 0.5 wavelengths equivalent to the highest operating wavelength of the radiating element in front of or behind one or both of the FSS layers 1701, 1702.

[0240] Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Throughout the text, like reference numerals represent like elements.

[0241] 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, without departing from the scope of the present invention, a first element may be termed a second element, and similarly, a second element may be termed a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0242] It will be understood that when an element is described as being "on" another element, the element may be directly on the other element, or there may also be an intermediate element. In contrast, when an element is described as being "directly on" another element, there is no intermediate element. It will also be understood that when an element is described as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or there may be an intermediate element. In contrast, when an element is described as being "directly connected" or "directly coupled" to another element, there is no intermediate element. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.).

[0243] Relative terms, such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region, as shown in the accompanying drawings. It is to be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the accompanying drawings.

[0244] The term "about" as used in connection with a number refers to a variation of + / - 10%.

[0245] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It will also be understood that the terms "comprises", "comprising" and / or "having", when used herein, specify the presence of the stated features, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

[0246] Aspects and elements of all the embodiments disclosed above may be combined in any manner and / or combined with aspects or elements of other embodiments to provide a plurality of additional embodiments.

Claims

1. A base station antenna, comprising: A first frequency selective surface (FSS), the first frequency selective surface including a first array of unit cells; And A second FSS, the second FSS including a second array of unit cells, Wherein the first FSS is stacked in front of the second FSS in the Z direction in the base station antenna, wherein each unit cell in the first array of unit cells and each unit cell in the second array of unit cells includes a plurality of spaced-apart inductor structures, and wherein a first unit cell in the first array of unit cells is aligned with a first unit cell in the second array of unit cells in the X-Y direction, whereby the corresponding inductor structures of the first unit cell are aligned with the corresponding inductor structures of the first unit cell in the second array of unit cells.

2. The base station antenna according to claim 1, wherein the first unit cell in the first array of unit cells includes a perimeter, wherein a first adjacent unit cell and a second adjacent unit cell share a perimeter side, and wherein the inductor structures of the first adjacent unit cell and the second adjacent unit cell are electrically connected.

3. The base station antenna according to claim 1, wherein the inductor structures of the first unit cell in the first array and the first unit cell in the second array are arranged to be located on the outer perimeter of the corresponding first unit cell or on a curved protrusion adjacent to the outer perimeter of the corresponding first unit cell.

4. The base station antenna according to claim 1, wherein the first unit cell in each of the first array of unit cells and the second array of unit cells includes a center and four linear segments protruding outward from the center, wherein the four linear segments are orthogonal to each other, and wherein the four linear segments are each incorporated into at least one of the inductor structures of its corresponding inductor structure.

5. The base station antenna according to claim 4, wherein the corresponding inductor structure of each unit cell includes protrusions serially protruding outward from opposite sides of the lateral or longitudinal centerline of the corresponding linear segment, and wherein the protrusions of the inductor structure of the first unit cell in the second array extend beyond the boundaries of the protrusions of the first unit cell in the first array of unit cells.

6. The base station antenna according to claim 1, wherein the inductor structures of adjacent unit cells in the first array of unit cells define a parallel inductor circuit.

7. The base station antenna according to claim 1, wherein one inductor structure of the first unit cell in the first array of unit cells is incorporated into one inductor structure of an adjacent second unit cell in the first array of unit cells at the shared perimeter side.

8. The base station antenna according to claim 1, wherein the inductor structures are only located on the perimeters of the corresponding unit cells in each of the first array of unit cells and the second array of unit cells.

9. The base station antenna according to claim 4, wherein the first unit cell in the first array of the unit cells and the second array of the unit cells further includes a curved segment surrounding the center, and wherein the four linear segments extend from four sides of the curved segment surrounding the center.

10. The base station antenna according to claim 4, wherein the four linear segments are internal linear segments, wherein the first unit cell further includes four external linear segments, and wherein one of the inductor structures in the inductor structure is located between a pair of the external linear segments and the internal linear segments.

11. The base station antenna according to claim 1, further comprising a third FSS located behind the second FSS, the third FSS having a third array of unit cells.

12. The base station antenna according to claim 1 further comprises: A passive antenna having the first FSS and the second FSS in a housing; And an active antenna unit located behind the housing.

13. The base station antenna according to claim 1, further comprising a first plurality of radiating elements located in front of the first FSS and a second plurality of radiating elements located behind the second FSS.

14. The base station antenna according to claim 13, wherein the first plurality of radiating elements operate in a first frequency band, and the second plurality of radiating elements operate in a second frequency band.

15. The base station antenna according to claim 14, wherein the first plurality of radiating elements include low-band radiating elements configured to operate in the first frequency band, and the second plurality of radiating elements include higher-band radiating elements configured to operate in the second frequency band, the second frequency band covering frequencies higher than the first frequency band.

16. The base station antenna according to claim 15, wherein the first FSS and the second FSS are configured to allow RF energy in the second frequency band to propagate through the first FSS and the second FSS.

17. The base station antenna according to claim 1, wherein the first FSS includes a first subset of the first array of the unit cells, the first subset being configured to block and / or reflect RF energy in the first frequency band while allowing RF energy in the second frequency band to propagate through the first FSS, wherein the first FSS includes a second subset of the first array of the unit cells, the second subset being configured to block and / or reflect RF energy in the first frequency band and RF energy in a third frequency band, and wherein the third frequency band includes frequencies between the first frequency band and the second frequency band.

18. The base station antenna according to claim 17, wherein the first subset of the first array of the unit cells is located at an upper portion of the base station antenna, and wherein the second subset of the first array of the unit cells includes unit cells to the right of the first subset of the unit cells and further includes unit cells to the left of the first subset of the unit cells.

19. The base station antenna according to claim 14, wherein the first plurality of radiating elements includes high-band radiating elements operating in at least a portion of the 3.2 - 4.1 GHz frequency band, and wherein the second plurality of radiating elements includes radiating elements operating in at least a portion of a frequency band lower than that of the high-band radiating elements.

20. The base station antenna according to claim 19, wherein the first FSS and the second FSS are configured to allow RF energy in at least a portion of the 3.2 - 4.1 GHz frequency band to propagate through the first FSS and the second FSS.

21. The base station antenna according to claim 13, wherein the second plurality of radiating elements are arranged as a multi-column array in an active antenna module.

22. The base station antenna according to claim 1, wherein at least some of the unit cells in the first array of the unit cell and / or the second array of the unit cell include at least one transmission line (TX) segment configured to be electrically coupled to at least one inductor structure.

23. The base station antenna according to claim 22, wherein the length of the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

24. The base station antenna according to claim 22, wherein the length of the at least one TX line segment is approximately half a wavelength of a defined frequency response point, optionally a second frequency response point f2.

25. A base station antenna, comprising: a first frequency selective surface (FSS), the first frequency selective surface including a first array of unit cells; and a second FSS, the second FSS including a second array of unit cells, wherein the first FSS is stacked in front of the second FSS in the Z direction in the base station antenna, and wherein at least some of the unit cells in the first array of the unit cell and the second array of the unit cell are configured to provide an equivalent circuit, the equivalent circuit including at least one inductor and at least one transmission line (TX) segment configured to be electrically coupled to at least one inductor.

26. The base station antenna according to claim 25, wherein the length of the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180-degree phase shift at a defined frequency.

27. The base station antenna according to claim 25, wherein the length of the at least one TX line segment is approximately half a wavelength of a defined frequency response point.

28. The base station antenna according to claim 25, wherein the unit cells provided by the first array and the unit cells provided by the second array are electrically coupled.

29. The base station antenna according to claim 25, wherein a first unit cell in the first array of the unit cell is electrically coupled to a first unit cell in the second array of the unit cell, whereby the first unit cell cooperates to define an equivalent circuit to reject or block radio frequency signals from radiating elements operating in a first frequency band and pass signals from radiating elements operating in a second frequency band.

30. A grid reflector for a base station antenna, comprising: A frequency selective surface (FSS), the frequency selective surface comprising an array of unit cells; And Wherein at least some of the unit cells in the array of unit cells comprise at least one transmission line (TX) segment.

31. The grid reflector according to claim 30, wherein the length of the at least one TX line segment is approximately half a wavelength defining a frequency response point f2.

32. The grid reflector according to claim 30, wherein the at least one TX line segment is configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180° phase shift at a defined frequency.

33. The grid reflector according to claim 30, wherein at least some of the unit cells having the at least one transmission line segment reject radio frequency signals in a first frequency band and a second larger frequency band corresponding to the defined frequency.

34. The grid reflector according to claim 30, wherein the at least one TX line segment comprises adjacent parallel conductive lines.

35. A grid reflector for a base station antenna, comprising: A frequency selective surface (FSS), the frequency selective surface comprising a first array of unit cells having a first configuration and a second array of cells having a second configuration, wherein the first array comprises unit cells having a square shape, and the second array comprises unit cells having a hexagonal shape, and wherein the first array extends inwards across 30 - 80% of the width of the FSS, and the second array is arranged in two columns on the right and left portions of the first array.

36. The grid reflector according to claim 35, wherein at least some of the unit cells in the array of unit cells comprise at least one transmission line (TX) segment, the length of the at least one transmission line segment being configured such that a radio frequency signal from a radiating element passing through the at least one TX line segment undergoes a 180 - degree phase shift at a defined frequency.

37. The grid reflector according to claim 35, wherein the FSS is configured to have a response frequency f0 of approximately 2.5 GHz, and provides a band - pass frequency range and a band - stop frequency range.

38. The grid reflector according to claim 35, wherein the at least one TX line segment has a length L, the length being approximately half a wavelength defining a frequency response point.

39. The grid reflector according to claim 35, wherein the at least one TX line segment comprises adjacent parallel conductive lines.

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