Base station antenna with lightweight hybrid cylindrical metamaterial lens

Abstract

The present disclosure relates to a base station antenna with a lightweight hybrid cylindrical metamaterial lens. The base station antenna includes a cylindrical RF lens and at least one radiating element. The cylindrical RF lens is a hybrid lens including both metamaterial focusing elements and dielectric material focusing elements. The RF lens can include concentric multiple cylindrical plies with conductive scattering elements formed thereon and thin dielectric plies to enhance the performance of the sparsely spaced scattering elements to achieve a well-defined pattern with low side lobes and low cross-polar discrimination.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 774,288, filed March 19, 2025, and U.S. Provisional Application Serial No. 63 / 895,566, filed October 8, 2025, the entire contents of each of these applications are incorporated herein by reference as if they were applied in their entirety. Technical Field

[0003] This invention relates to base station antennas for cellular communication systems, and more specifically, to base station antennas having cylindrical metamaterial radio frequency (“RF”) lenses. Background Technology

[0004] Cellular communication systems are well known in the art. In a typical cellular communication system, a geographical area is divided into a series of areas called “cells,” and each cell is served by a base station. A base station may include baseband equipment, radio equipment, and base station antennas configured to provide bidirectional radio frequency (“RF”) communication with subscribers located throughout the cell. In many cases, a cell may be divided into multiple “sectors” in an azimuth plane (a horizontal plane that bisects the antenna and is parallel to the plane defined by a horizontal line), and a separate base station antenna provides coverage to each sector. Base station antennas are often mounted on towers or other elevated structures, where the radiation pattern (“antenna beam”) generated by the antenna is pointed outward to provide service to the corresponding sector. This document will also refer to an elevation plane, which is a plane perpendicular to the azimuth plane that bisects the front surface of the base station antenna.

[0005] A common base station configuration is a "three-sector" configuration, where the cell is divided into three 120° sectors in the azimuth plane, and the base station includes three base station antennas providing coverage to the three corresponding sectors. Typically, each base station antenna will include one or more phased arrays of dual-polarized radiating elements. A dual-polarized radiating element is a radiating element comprising a first radiator that transmits and receives RF energy in a first polarization, and a second radiator that transmits and receives RF energy in a second polarization orthogonal to the first polarization. For passive (active beamforming) applications, each array typically includes a vertically extending column of radiating elements referred to as a "linear array" of radiating elements, although it will be understood that in some cases, one or more radiating elements in the linear array may be offset horizontally from the remaining radiating elements to narrow the azimuth beamwidth of the antenna beam generated by the linear array, and in some cases, the linear array may comprise a single radiating element. Each linear array of radiating elements is coupled to a pair of ports of a radio device via a corresponding first-polarization feed network and a second-polarization feed network. An RF signal input at a first radio port is split into multiple sub-components by a first polarization feed network and fed to a first polarization radiator of a radiating element in a linear array. The first polarization radiator radiates the sub-components of the RF signal into free space, thereby generating a first antenna beam. Similarly, an RF signal received from a second radio port is split into multiple sub-components by a second polarization feed network and fed to a second polarization radiator of a radiating element in a linear array, thereby generating a second antenna beam. The phase of the sub-components of the RF signal fed to different radiating elements in the linear array can be (e.g., by the length of the RF transmission lines in the feed network) configured such that the RF energy radiated by the different radiating elements is constructively combined to narrow the beamwidth of the antenna beam in the column direction. A narrower antenna beam concentrates the RF energy into a smaller area, thereby increasing the antenna beam gain.

[0006] The shape of each antenna beam generated by a linear array of radiating elements is, among other things, defined by the characteristics of the individual radiating elements, the characteristics of the array (e.g., whether the array consists of single radiating elements or columns of radiating elements, the spacing between adjacent radiating elements in the linear array, and any horizontal interleaving within the columns), and the amplitude and phase of the sub-components of the RF signal fed to each individual radiating element in the linear array. Antenna beams are often characterized by their half-power beamwidth (“HPBW”). HPBW refers to the degree in a specified plane such as the azimuth plane or elevation plane, where the radiated power of the main lobe of the antenna beam is within 3 dB (50%) of the peak power of the antenna beam. Typically, the radiating elements used in base station antennas are configured to produce an “element” radiation pattern (i.e., an antenna beam formed by a single radiating element) with an HPBW of approximately 65° in both the azimuth and elevation planes. This ensures that the antenna beam generated by each radiating element provides good coverage across the entire 120° sector in the azimuth plane. If the linear array comprises multiple radiating elements, the subcomponents of the RF signal fed to the different radiating elements in the column can be synchronized in phase, such that the radiation patterns generated by each subset of one or more radiating elements are constructively combined to produce a synthetic antenna beam with a narrow HPBW (e.g., 5°–25°) in the elevation (vertical) plane.

[0007] As capacity demands grow, cellular network operators are now dividing some cells into more than three sectors. For example, a cell can now be divided into six, nine, twelve, fifteen, or eighteen sectors in the azimuth plane. Typically, when a cell is divided into more than three sectors, a multi-beam “sector-splitting” antenna is used. A multi-beam sector-splitting antenna refers to a base station antenna that generates multiple antenna beams (per polarization) with narrow beamwidths in the azimuth plane (i.e., less than about 60°, and typically less than about 35° azimuth HPBW), where the pointing directions of the multiple antenna beams (per polarization) are designed to divide the sector into multiple sub-sectors. This allows a single base station antenna to generate multiple antenna beams (per polarization) providing coverage to the corresponding sub-sectors of a 120° sector.

[0008] For example, a six-sector base station will divide each 120° sector into two 60° sub-sectors in the azimuth plane. Such a six-sector base station will typically be served by three base station antennas, each implemented as a "dual-beam" antenna. This dual-beam antenna is designed to generate a first antenna beam and a second antenna beam (per polarization) providing coverage to the corresponding first and second 60° sub-sectors of each 120° sector. Each antenna beam may have an HPBW of approximately 30-35° in the azimuth plane. The first antenna beam may be pointed at an angle of approximately -27° to -30° relative to the antenna's aiming direction in the azimuth plane, and the second antenna beam may be pointed at an angle of approximately 27° to 30° relative to the antenna's aiming direction in the azimuth plane. The antenna's aiming direction is the center of the 120° sector served by the antenna in the azimuth plane. In this way, the 120° sector is divided into two 60° sub-sectors, which are covered by the corresponding first antenna beam and second antenna beam.

[0009] Providing cellular service in large venues (such as stadiums, arenas, conference centers, concert halls, etc.) can be particularly challenging because a very large number of users can be located in a very small area. In such venues, multi-beam sector segmentation of base station antennas can be used, generating three or more antenna beams per polarization, where each antenna beam provides coverage to a corresponding sub-sector of 20°–40° (or less) in the azimuth plane. When a 120° sector is subdivided into sub-sectors, system capacity can be significantly increased because the RF energy of each antenna beam is focused into a smaller area, thus providing higher antenna gain.

[0010] There are two common approaches for implementing multi-beam antennas. In the first approach, a multi-column antenna array is provided, coupled to a beamforming network such as a Butler matrix-based beamforming network. Multiple RF signals (per polarization) are input to the beamforming network, which subdivides the signals and feeds them to the multi-column array. The beamforming network can be configured to generate a separate antenna beam for each RF signal input to it, and the generated antenna beams can be electronically manipulated so that they are pointed in different directions. Such an antenna can be designed to generate an antenna beam (per polarization) for each sub-sector of the sector served by the antenna, where the antenna beam is pointed to the corresponding sub-sector.

[0011] A second approach to implementing a multi-beam antenna involves including multiple linear arrays arranged behind one or more RF lenses. The RF lenses are used to narrow the beamwidth of the antenna beam generated by the base station antenna, thereby increasing the antenna beam gain. For example, the RF lenses can be planar, cylindrical, or spherical RF lenses. Each linear array is positioned such that its generated antenna beam will strike one or more RF lenses, with each antenna beam pointing towards a corresponding sub-sector. The RF lenses concentrate the RF radiation into a more focused (i.e., narrower) antenna beam, at least in the azimuth plane, such that each antenna beam will be appropriately sized to serve a corresponding sub-sector of the sector served by the base station antenna. RF lenses are conventionally formed using dielectric materials such as polyethylene, and combinations of dielectric materials with different relative permittivity are often used to achieve the desired focusing effect. Unfortunately, the size, weight, and / or cost of such dielectric lenses are often prohibitive if a significant narrowing of the antenna beam is required. Metamaterial RF lenses have also been proposed. Metamaterials, also known as artificial dielectric materials, are a class of materials that possess properties not typically found in natural materials, such as negative refractive index. Metamaterial RF lenses typically comprise multiple conductive elements that are small relative to the wavelength of the RF energy to be focused (e.g., the maximum size of each conductive element is less than half the minimum wavelength of the RF energy to be focused, and often less than one-tenth of the minimum wavelength). For example, U.S. Patent Publication No. 2024 / 0347922 (“'922 Publication”) discloses various metamaterial RF lenses suitable for use in base station antennas.

[0012] Figure 1 This is a side perspective view of an antenna that includes a cylindrical Luneburg lens formed using a graded dielectric material having a higher relative permittivity near the axis of the cylindrical lens and decreasing radially to a lower relative permittivity near the periphery of the cylinder, as disclosed in European Patent No. 3401999. This solution is heavy and expensive, especially in the sub-6 GHz frequency range, where narrow-beam antennas require cylindrical lenses with large physical diameters.

[0013] Figure 2 This is a side perspective view of a cylindrical RF lens, which is a stepped approximation of the Lumber lens disclosed in U.S. Patent Publication No. 2019 / 0393614. Figure 2 The cylindrical RF lens shown comprises a low-density dielectric foam of concentric rings loaded with varying amounts of high dielectric constant material, thus providing a lens in the form of a concentric cylindrical assembly with a varying relative dielectric constant. Summary of the Invention

[0014] According to some embodiments of the present invention, an antenna is provided comprising a cylindrical RF lens and radiating elements arranged to irradiate the cylindrical RF lens. The cylindrical RF lens comprises a plurality of substantially planar dielectric plates and a plurality of concentric cylindrical dielectric shells, each dielectric plate extending in a respective radial direction and having a first edge adjacent to the axis of the cylindrical RF lens, wherein the angles between the radial directions are equal, and wherein each dielectric shell supports a plurality of conductive scattering elements arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0015] In some embodiments, the cylindrical RF lens includes more dielectric plates than a cylindrical dielectric shell. In some embodiments, the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell. In some embodiments, the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell. In some embodiments, the dielectric plates do not have conductive scattering elements.

[0016] In some embodiments, each dielectric plate includes a plurality of slots extending parallel to the axis of the cylindrical RF lens. In such embodiments, a cylindrical dielectric shell may be received within a slot in the dielectric plate.

[0017] In some embodiments, the average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating band of the radiating element.

[0018] In some embodiments, the radiating element is a first radiating element, and the antenna further includes a second radiating element. In such embodiments, the first and second radiating elements may be stacked along an axis extending parallel to the axis of the cylindrical RF lens, or they may be spaced apart from each other in a plane perpendicular to the axis of the cylindrical RF lens.

[0019] According to a further embodiment of the present invention, a base station antenna is provided, the base station antenna including a radiating element and a cylindrical RF lens, the cylindrical RF lens including a plurality of concentric cylindrical dielectric shells, wherein each dielectric shell supports a plurality of conductive scattering elements arranged in rows and columns, the rows and columns being aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0020] In some embodiments, the cylindrical RF lens further includes a plurality of dielectric plates, each extending in a respective radial direction and having a first edge adjacent to the axis of the cylindrical RF lens. In some embodiments, the angles between the radial directions are equal.

[0021] In some embodiments, the cylindrical RF lens includes more dielectric plates than a cylindrical dielectric shell. In some embodiments, the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell. In some embodiments, the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell. In some embodiments, the dielectric plates do not have conductive scattering elements.

[0022] In some embodiments, each dielectric plate includes a plurality of slots extending parallel to the axis of the cylindrical RF lens. In such embodiments, a cylindrical dielectric shell is received within a slot in the dielectric plate.

[0023] In some embodiments, the average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating band of the radiating element.

[0024] According to an additional embodiment of the invention, a base station antenna is provided, which includes a radiating element and a cylindrical RF lens. The cylindrical RF lens includes a cylindrical support element and a plurality of planar dielectric plates extending radially outward from the cylindrical support element.

[0025] In some embodiments, the cylindrical support element includes a plurality of slots extending parallel to the axis of the cylindrical RF lens. In some embodiments, each planar dielectric plate is received in a corresponding slot within the slots.

[0026] In some embodiments, the cylindrical RF lens further includes a plurality of concentric cylindrical dielectric shells, each dielectric shell supporting a plurality of conductive scattering elements. In some embodiments, the conductive scattering elements are arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0027] In some embodiments, the cylindrical RF lens includes more dielectric plates than a cylindrical dielectric shell. In some embodiments, the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell. In some embodiments, the dielectric plates do not have conductive scattering elements. In some embodiments, the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell.

[0028] According to other embodiments of the present invention, a base station antenna is provided, the base station antenna including a cylindrical RF lens and a radiating element, the cylindrical RF lens including a first layer plate assembly, each first layer plate extending radially outward from an axial direction, and the radiating element being configured to radiate toward the cylindrical RF lens. Each first layer plate includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0029] In some embodiments, the cylindrical RF lens further includes a second layer group, each second layer intersecting at least two first layers. In some embodiments, each second layer extends in a corresponding plane parallel to a plane defined by the main surface of each first layer.

[0030] In some embodiments, the first number of first layers in the first layer group exceeds the second number of second layers in the second layer group. In some embodiments, the thickness of at least one second layer exceeds the thickness of at least one first layer. In some embodiments, the thickness of at least one second layer exceeds the thickness of each first layer.

[0031] In some embodiments, each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate, and each second layer includes a dielectric substrate, which may optionally have one or more conductive scattering elements on at least one main surface thereon, wherein the density of conductive scattering elements on at least one first layer exceeds the density of conductive scattering elements on at least one second layer. In some embodiments, the respective density of conductive scattering elements on each first layer exceeds the density of conductive scattering elements on at least one second layer.

[0032] In some embodiments, each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate, and at least one second layer has no conductive scattering elements.

[0033] In some embodiments, the first layer is a rectangular layer.

[0034] In some embodiments, the cylindrical RF lens further includes a cylindrical support element, wherein the edge of each first layer plate is received in a corresponding slot in a groove of the cylindrical support element.

[0035] According to a further embodiment of the present invention, a base station antenna is provided, comprising a cylindrical RF lens and a radiating element. The cylindrical RF lens includes a first layer group and a second layer group, each first layer extending in a corresponding vertical plane among a plurality of vertical planes, and each second layer extending in a corresponding horizontal plane among a plurality of horizontal planes; the radiating element is configured to radiate toward the RF lens. Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0036] In some embodiments, the first number of first layers in the first layer group exceeds the second number of second layers in the second layer group. In some embodiments, the thickness of at least one second layer exceeds the thickness of at least one first layer. In some embodiments, the density of conductive scattering elements on at least one first layer exceeds the density of conductive scattering elements on at least one second layer. In some embodiments, at least one second layer has no conductive scattering elements.

[0037] According to a further embodiment of the invention, a base station antenna is provided, comprising a cylindrical RF lens having a central axis and radiating elements configured to radiate toward the RF lens. The cylindrical RF lens includes a first plate group and a second plate group, each first plate extending radially outward from the central axis, and each second plate perpendicular to the central axis. A first number of first plates in the first plate group exceeds a second number of second plates in the second plate group.

[0038] In some embodiments, the first quantity is at least three times the second quantity. In some embodiments, the thickness of at least one second layer exceeds the thickness of at least one first layer. In some embodiments, each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate. In some embodiments, the density of conductive scattering elements on at least one first layer exceeds the density of conductive scattering elements on at least one second layer.

[0039] According to another embodiment of the invention, a base station antenna is provided, comprising a cylindrical RF lens and radiating elements configured to radiate toward the RF lens. The cylindrical RF lens includes a first layer group and a second layer group, each first layer extending in a corresponding vertical plane among a plurality of vertical planes, and each second layer extending in a corresponding horizontal plane among a plurality of horizontal planes. Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate, and each second layer includes a dielectric substrate, wherein the density of conductive scattering elements on at least one first layer exceeds the density of conductive scattering elements on at least one second layer.

[0040] In some embodiments, the first number of first layers in the first layer group exceeds the second number of second layers in the second layer group. In some embodiments, the thickness of at least one second layer exceeds the thickness of at least one first layer. In some embodiments, the density of conductive scattering elements on at least one first layer exceeds the density of conductive scattering elements on all second layers. In some embodiments, at least one second layer has no conductive scattering elements. Attached Figure Description

[0041] Figure 1It is a schematic perspective view of a conventional antenna, including a stepped approximation of a cylindrical RF Lombard lens formed using conventional dielectric materials.

[0042] Figure 2 This is a schematic perspective view of a conventional cylindrical RF Lombard lens formed using artificial dielectric materials.

[0043] Figure 3A This is a schematic perspective view of a base station antenna, which includes a radiating element, a reflector, and an RF lens, the RF lens comprising a plurality of planar dielectric plates arranged radially around a common longitudinal axis.

[0044] Figure 3B The simulation was performed when the radiating element was placed at two different locations behind the RF lens. Figure 3A A diagram showing the radiation pattern generated by the base station antenna.

[0045] Figure 4A This is a schematic perspective view of a base station antenna according to an embodiment of the present invention. The base station antenna includes a radiating element, a reflector, and a cylindrical RF lens formed by a plurality of concentric cylindrical dielectric shells having conductive scattering elements thereon.

[0046] Figure 4B It is a simulation of Figure 4A The diagram shows the common polarization and cross polarization responses generated by the base station antenna.

[0047] Figure 5A yes Figure 4A A schematic diagram of the axis, polarization plane, and relative orientation of rows and columns of conductive scattering elements on one of the dielectric shells of a base station antenna's cylindrical RF lens.

[0048] Figure 5B This simulation is performed when the conductive scattering elements are relatively far apart. Figure 4A The diagram shows the common polarization and cross polarization radiation patterns generated by the base station antenna.

[0049] Figure 6 This is a schematic exploded perspective view of another lens base station antenna according to an embodiment of the present invention.

[0050] Figure 7 When fully assembled Figure 6 A schematic perspective view of a base station antenna.

[0051] Figure 8 This is a schematic perspective view of a base station antenna, which includes two antennas attached to each other. Figure 7 Base station antennas.

[0052] Figure 9 This is a schematic perspective view of a base station antenna according to a further embodiment of the present invention, the base station antenna being arranged in a housing.

[0053] Figure 10 yes Figure 9 A schematic perspective view of a base station antenna, with a weatherproof antenna cover added.

[0054] Figure 11 It is shown Figure 10 A diagram showing the azimuth radiation pattern measured by the base station antenna.

[0055] Figure 12 It is shown Figure 8 A diagram showing the elevation radiation pattern measured by the base station antenna.

[0056] Figure 13A This is a cross-sectional view of a base station antenna according to an embodiment of the present invention, the base station antenna comprising three linear arrays of radiating elements located at different azimuth angles relative to the axis of a cylindrical RF lens that is part of the base station antenna.

[0057] Figures 13B-13D The signal radiated from each linear array of the radiating element propagates through Figure 13A The calculated wavefront for the cylindrical RF lens shown.

[0058] Figure 14 It is from Figure 13A The signal radiated by the base station antenna forms a pattern of radiation in the MVG near-field chamber, with each of the three independent antenna beams providing a measurement pattern.

[0059] Figure 15 yes Figure 7 A schematic perspective view of a cylindrical RF lens, which also shows the volume consumed by the components of the cylindrical RF lens.

[0060] Figures 16A-16D These are, respectively, a front view, a top view, a side view, and a perspective view of a base station antenna according to a further embodiment of the present invention, the base station antenna including a hybrid cylindrical RF lens.

[0061] Figure 17 yes Figures 16A-16D A diagram showing the azimuth radiation pattern of a base station antenna.

[0062] Figure 18 This is a top view of a dual-beam base station antenna according to an embodiment of the present invention, the dual-beam base station antenna including... Figures 16A-16D The antenna has the same cylindrical RF lens.

[0063] Figure 19A and Figure 19B This is a schematic perspective view of a dual-band base station antenna according to a further embodiment of the present invention, the dual-band base station antenna including a cylindrical RF lens.

[0064] Figure 20 This is a side perspective view of the internal components of a base station antenna according to a further embodiment of the present invention. Detailed Implementation

[0065] According to embodiments of the present invention, a base station antenna is provided comprising lightweight and easily manufactured cylindrical metamaterial RF lenses, which exhibit good radiation patterning and cross-polarization performance. Base station antennas according to some embodiments of the present invention include cylindrical lenses, each comprising a plurality of concentric cylindrical dielectric shells, wherein at least some of the dielectric shells support a plurality of conductive scattering elements, which may be arranged, for example, in rows and columns. In some embodiments, the conductive scattering elements may extend along an axis at a 45° angle relative to the longitudinal axis of the cylindrical RF lens. These cylindrical RF lenses may also include a plurality of dielectric plates, which may have no conductive scattering elements (or fewer conductive scattering elements), further focusing the RF radiation incident on the cylindrical RF lens. In some embodiments, the dielectric plates may include supports that help hold the concentric cylindrical dielectric shells in place while also serving as supports for the lens elements that further focus the incident RF radiation.

[0066] According to a further embodiment of the invention, a base station antenna is provided, comprising cylindrical RF lenses including a first set of plates extending radially outward from a vertical axis and a second set of plates extending in corresponding horizontal planes. Each first plate may include, for example, a dielectric substrate having a plurality of conductive scattering elements thereon. Each second plate may include, for example, a dielectric substrate having fewer or no conductive scattering elements thereon. The first plates may be arranged to define a cylindrical shape. The conductive scattering elements on the first plates may focus incident RF radiation, but may be slightly sparsely distributed on the first plates to ensure that cross-polarization discrimination performance is acceptable. The second plates may perform additional focusing of the incident RF radiation to achieve a desired amount of focusing within a given cylindrical volume.

[0067] Now refer to Figures 3A-20 A base station antenna according to embodiments of the present invention is described. It will be understood that the antenna disclosed herein has reciprocal characteristics, whether transmitting or receiving signals. In the following description, any mode or characteristic of operation when transmitting a signal, described explanatoryly, has the same or similar mode or characteristic when receiving a signal.

[0068] Figure 3AThis is a schematic perspective view of a base station antenna 10, which includes a radiating element 11 and a reflector in the form of a conductive plate 12 that functions to direct energy toward the axis of an RF lens comprising a plurality of substantially planar dielectric members 13, hereinafter referred to as dielectric plates 13, arranged radially around a common longitudinal axis. Each dielectric plate 13 is characterized by its axial height, radial width, thickness, and relative permittivity. In the example shown, the radiating element 11 is in the form of a crossed dipole radiating element, and the reflector 12 is a substantially planar metallic reflector that may be formed, for example, from a sheet of metal. It will be understood that the dielectric plates 13 provide a certain degree of focusing in the radial direction of the RF energy transmitted through them, and thus function as a lens. However, the arrangement of the dielectric plates 13 is symmetrical only when viewed from certain directions (i.e., when aligned with the radial plates and when aligned with the bisector of the angle between adjacent radial plates).

[0069] The effectiveness of the arrangement of dielectric plates 13 in focusing energy depends on the polarization of the energy radiated by the radiating element 11, as well as the choice of the size of the dielectric plates 13 and the materials used to make them.

[0070] Figure 3B When the radiating element 11 is located at two different positions around the contour of the dielectric member 13, it is caused by Figure 3A The diagram shows the radiation pattern produced by the base station antenna 10. Radiation pattern 14 is produced when radiating element 11 is located at position 1. Radiation pattern 15 is produced when radiating element 11 is located at position 2. As discussed above, sector-segmented antennas that use RF lenses to narrow the antenna beam deploy multiple linear arrays of radiating elements behind one or more RF lenses, where each linear array has one or more radiating elements. Ideally, regardless of where the linear array is located behind the RF lens, the radiation pattern produced by each linear array (after passing through the RF lens) will be the same, so that the antenna beam serving each sub-sector will exhibit the same performance. Figure 3B The cylindrical RF lens formed by dielectric plate 13 is shown to be effective in narrowing the antenna beam generated by radiating element 11. However, for at least some radiating element locations (corresponding to curve 15), the sidelobe levels are very high (less than 8 dB below the peak of the main lobe), which is unacceptable in cellular applications. Therefore, Figure 3A The base station antenna 10 may not be suitable for most cellular networks, but it does demonstrate the focusing capability of the dielectric component 13 by enabling narrow beam radiation patterns.

[0071] Figure 4AThis is a schematic perspective view of a base station antenna 40, which includes a radiating element 41, a reflector 42, and a cylindrical RF lens 43. The reflector 42 is oriented to reflect RF energy emitted rearward by the radiating element 41 toward the cylindrical RF lens 43. The cylindrical RF lens 43 includes a plurality of concentric cylindrical dielectric shells 44, 45, 46, 47, each shell having an arrangement of conductive scattering elements 48 thereon. In some embodiments, the concentric cylindrical dielectric shells 44, 45, 46, 47 having conductive scattering elements 48 thereon can be implemented using a flexible printed circuit board.

[0072] In some embodiments, the scattering element 48 may be ring-shaped, but many other shapes are also possible. The conductive scattering element 48 may be in the form of concentric circles or concentric squares, as described in U.S. Patent Application Serial No. 18 / 298,795, but the invention is not limited to using these shapes. The conductive scattering element included in the cylindrical RF lens may have a size small compared to the wavelength at the operating frequency of the base station antenna. For example, the size of each scattering element 48 may be on the order of 0.05 wavelengths.

[0073] Figure 4B This diagram illustrates the typical common polarization (curve 49) and cross-polarization (curve 50) responses of the base station antenna 40 when the scattering elements 48 are placed close together. The common polarization pattern 49 has a very good shape, but the cross-polarization pattern 50 has a peak value only about 5 dB lower than the peak common polarization value, meaning that almost one-third of the RF power transmitted in the first polarization is converted to the second (orthogonal) polarization. Cellular network operators typically expect the peak cross-polarization value to be much lower, such as at least 15 dB or even 20 dB lower than the peak common polarization value. Therefore, the base station antenna 40 is generally not suitable for use in mobile communication networks.

[0074] In embodiments where the radiating element 41 is configured to radiate a signal having biorthogonal linear polarization (e.g., polarization directions of +45° and -45° relative to the axis of a cylindrical RF lens), preferably, the scattering elements 48 are arranged such that the row and column spacing of the scattering elements 48 is equal, and the rows and columns are aligned with the polarization directions, such as... Figure 5A As shown in the diagram. The typical spacing between rows and between columns is 0.25 wavelengths. Note that in this document, the reference to "axis" for a cylindrical RF lens refers to an axis extending through the center of the two parallel circular bases of the cylinder defined by the cylindrical RF lens.

[0075] Figure 5A This is a schematic diagram of a small portion of one of the dielectric shells 44, 45, 46, and 47 on which a conductive scattering element 48 is formed, of the cylindrical RF lens of Figure 4. Figure 5AThe orthogonal polarization planes 52 and 53 of the dual-polarized radiating element 51, which has a dipole radiator oriented at ±45° relative to the axis of lens 54, are shown by dashed lines. Conductive scattering elements 48 are arranged in rows and columns, preferably aligned with polarization planes 52 and 53, as shown. Figure 5A In the diagram, a small portion of one of the dielectric shells is shown after being unfolded into a flat sheet of material; in actual embodiments, such as Figure 4A As seen in the image, dielectric shells 44, 45, 46, and 47 are formed as concentric cylindrical dielectric shells with a common axis 54.

[0076] Figure 5A The arrangement can also preferably be used with an illumination linear array having one or more circularly polarized radiating elements. When Figure 4A When the cylindrical RF lens 43 is used in conjunction with one or more linear arrays of radiating elements having radiators that transmit and receive RF signals in vertical and / or horizontal polarization, the columns of conductive scattering elements 48 may preferably be aligned with the longitudinal axis of the lens 43 such that the columns of conductive scattering elements 48 extend along the axis of the cylindrical RF lens 43.

[0077] The spacing between adjacent conductive scattering elements 48 can affect the... Figure 4A Both the common polarization pattern and cross-polarization discrimination performance of the antenna beam generated by the base station antenna 40. When the conductive scattering elements 48 are relatively far apart, such as at a distance of about 0.25 times or more the wavelength of the center frequency of the operating band of the radiating element 41, the cross-polarization discrimination is improved to 30 dB, but poor beam convergence is caused by the reduced number of conductive scattering elements 48, and the radiation pattern is wide (i.e., the beamwidths of 3 dB and 10 dB are greater than expected).

[0078] Although Figure 5A The illustration shows conductive scattering elements 48 positioned at equal intervals in both row and column directions; however, it will be understood that embodiments of the invention are not limited thereto. In practice, in some applications, it is preferable to position adjacent conductive scattering elements 48 very close to each other along the + / -45° polarization axis, and further apart along the vertical axis. For example, adjacent conductive scattering elements 48 may be spaced 14 mm diagonally along a 45° axis and 20 mm along the vertical axis, a ratio of 0.7. It will also be understood that... Figure 5A The illustration shows a relatively dense group of conductive scattering elements 48, while in other embodiments, the conductive scattering elements 48 can be more numerous. Figure 5A The spacing shown is much greater.

[0079] Figure 5B When the conductive scattering elements 48 are spaced apart from each other by a distance approximately 0.25 times the wavelength of the center frequency of the operating frequency band of the radiating element 41, for... Figure 4AThe diagram shows the simulated common polarization radiation pattern 55 and cross polarization radiation pattern 56 of the base station antenna 40. Figure 5B The simulation results shown are based on a cylindrical RF lens 43, which has the same characteristics as those used to generate Figure 3B and Figure 4B The simulation of the image uses a cylindrical RF lens 43 with the same aperture size. By comparison... Figure 4B and Figure 5B It can be seen that the co-polarization pattern 55 has a much wider beamwidth than the co-polarization pattern 49, which is due to the sparse density of the conductive scattering elements 48. However, compared with... Figure 4B Compared to the cross-polarization pattern 50, the cross-polarization pattern 56 (in the aiming direction) is significantly improved by 30 dB, while the cross-polarization pattern 50 exhibits only about 5 dB of cross-polarization discrimination.

[0080] Figure 3A The arrangement performs well only for radiating elements positioned at a specific location behind the RF lens formed by the dielectric plate 13. When the density of conductive scattering elements 48 is high, Figure 4A The arrangement exhibits a poor common-polarization radiation pattern, and when the density of the conductive scattering elements 48 is low, it exhibits insufficient focusing. Therefore, individually, Figure 3A and Figure 4A The structure may be invalid. However, it can be corrected by using... Figure 3A RF lens and Figure 4A A novel combination of RF lenses is used to achieve high-level performance with low sidelobes, high gain and low cross-polarization, wherein the conductive scattering elements 48 are spaced far apart.

[0081] Figure 6 This is a schematic exploded perspective view of a base station antenna according to an embodiment of the present invention. The base station antenna includes a linear array of radiating elements comprising two radiating elements 67, 68, and a cylindrical RF lens. The cylindrical RF lens includes a radial assembly 61 of a dielectric plate, a plurality of substantially circular dielectric members 65, 66, and a plurality of concentric dielectric substrates 64 having conductive scattering elements 48 formed thereon. The dielectric plate constituting the radial assembly 61 is provided with a plurality of longitudinal grooves or ridges 62. The dielectric substrates 64 are received within the grooves 62 in the radial assembly 61. The width of each dielectric substrate 64 is dimensional such that when bent and assembled into the radial assembly 61, it conforms to a desired arcuate cross-sectional profile, such that the dielectric substrate 64... Figure 4A The arrangement shown is of multiple concentric dielectric substrates.

[0082] exist Figure 6In the exemplary embodiment of the invention shown, the radial assembly 61 includes eight radially extending dielectric plates, each arranged to support a flexible substrate forming five dielectric shells 64. In some embodiments, the dielectric plates included in the radial assembly 61 may have a relatively high dielectric constant to enhance the focusing of RF energy. In some embodiments, the dielectric plates may have a dielectric constant between 2.0 and 10.0, or between 2.5 and 10.0, or between 3.0 and 10.0. The dielectric plates may also be made thicker than the dielectric substrate 64 to enhance the focusing of RF radiation. In this embodiment, the complete assembly will include a set of five dielectric shells 64, each having the same axial length and a width arranged according to the diameter of each cylinder in a concentric cylindrical arrangement. The set of dielectric shells 64 is held by substantially circular dielectric members 65, 66, which are attached to the radial assembly 61 by screws or other means.

[0083] Figure 6 The electrical properties of the cylindrical RF lens are provided by the combination of the action of the radial assembly 61 of the dielectric plate and the action of the concentric cylindrical dielectric shell 64 having conductive scattering elements 48 formed thereon.

[0084] Cylindrical RF lenses are designed to focus incident RF radiation in a plane orthogonal to the axis of the cylindrical RF lens. Therefore, if a cylindrical RF lens is mounted such that the axis of the cylinder extends vertically, the cylindrical RF lens will focus incident RF radiation in the azimuth plane. Conventional cylindrical RF lenses do not focus RF energy in a radial plane parallel to the axis of the cylinder, and therefore cylindrical RF lenses mounted such that the axis of the cylinder extends vertically will not focus incident RF radiation in the elevation plane. Figure 6 As shown, to focus energy in the elevation plane, the cylindrical lens is illuminated by a linear array of two (or more) radiating elements 67, 68, arranged in columns extending parallel to the axis of the cylinder. As discussed above, the subcomponents of the RF signal fed to the individual radiating elements can be synchronized in phase, such that the individual antenna beams generated by the two radiating elements are constructively combined to form a composite antenna beam with a narrow beamwidth in the elevation plane. In this way, if the cylindrical RF lens is mounted vertically, RF radiation can be focused in both the radial and axial planes corresponding to the azimuth and elevation planes, respectively. Figure 6 The example shown has an array of two radiating elements 67, 68 fed from a common feed point 69.

[0085] Figure 7 It is the assembled Figure 6A schematic perspective view of the base station antenna. Circular dielectric members 65, 66 include an aperture 71 to reduce their weight and also facilitate inspection of the assembled antenna. Supports 72, 73 provide attachment for the feed arrangement 74 to the dielectric members 65, 66.

[0086] refer to Figure 5A , Figure 6 and Figure 7 According to certain embodiments of the invention, an antenna is provided comprising a cylindrical RF lens and radiating elements 67, 68 arranged to irradiate the cylindrical RF lens. The cylindrical RF lens includes an assembly 61 comprising a plurality of substantially planar dielectric plates and a plurality of concentric cylindrical dielectric shells 64, each dielectric plate extending in a respective radial direction and having a first edge adjacent to the axis of the cylindrical RF lens, wherein the angles between the radial directions are equal, and wherein each dielectric shell 64 supports a plurality of conductive scattering elements 48 arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0087] In some embodiments, the cylindrical RF lens includes more dielectric plates than the cylindrical dielectric shell 64. In some embodiments, the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell 64. In some embodiments, the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell 64. In some embodiments, the dielectric plates do not have conductive scattering elements 48.

[0088] In some embodiments, each dielectric plate includes a plurality of slots 62 extending parallel to the axis of the cylindrical RF lens. In such embodiments, a cylindrical dielectric shell 64 may be received within the slots 62 in the dielectric plate.

[0089] In some embodiments, the average spacing between adjacent conductive scattering elements 48 is at least 0.2 times or at least 0.25 times the wavelength, where “wavelength” is the wavelength corresponding to the center frequency of the operating frequency band of the radiating elements 67, 68.

[0090] refer to Figure 6 and Figure 7 According to an additional embodiment of the invention, a base station antenna is provided that includes a radiating element and a cylindrical RF lens, the cylindrical RF lens including a plurality of concentric cylindrical dielectric shells, wherein each dielectric shell supports a plurality of conductive scattering elements arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0091] Still referencing Figure 6 and Figure 7According to an additional embodiment of the invention, a base station antenna including a radiating element and a cylindrical RF lens is provided. The cylindrical RF lens includes a cylindrical support element and a plurality of planar dielectric plates extending radially outward from the cylindrical support element. In some embodiments, the cylindrical support element includes a plurality of slots extending parallel to the axis of the cylindrical RF lens. In some embodiments, each planar dielectric plate is received in a corresponding slot within the slots.

[0092] Figure 8 This is a schematic perspective view of an assembly 80 including two base station antennas 81 and 82 connected together by a support member 83. Each base station antenna 81 and 82 may have Figure 6 and Figure 7 The configuration is shown in the figure. In some embodiments, base station antennas 81 and 82 may be similar in size and operate in the same frequency band, while in other embodiments, they may have different configurations and operate in different frequency bands. If base station antennas 81 and 82 operate in different frequency bands, then they will typically be of different sizes.

[0093] Figure 9 This is a schematic perspective view of a base station antenna 90 including a cylindrical RF lens 91 according to a further embodiment of the present invention. The base station antenna 90 may correspond to... Figure 7 The base station antenna has additional components added to it. For example... Figure 9 As shown, the base station antenna 90 points towards Figure 7 The base station antenna includes end members 93 and 94, a support member 92, and multiple RF connectors 95. The RF connectors 95 are mounted in the lower end member 94 to feed RF signals to a linear array of radiating elements included in the base station antenna. The base station antenna 90 can be configured to operate as a 2xMIMO (Multiple-Input Multiple-Output) antenna, but if the two antennas are vertically stacked or arranged side-by-side, it can be configured to operate as a 4xMIMO antenna. In other embodiments, a second linear array can be added behind the cylindrical RF lens 91, spaced apart from the first linear array in the azimuth plane, and the base station antenna 90 can operate as a sector-splitting antenna that divides the coverage area into two sub-sectors covered in the azimuth plane by antenna beams generated by the two corresponding linear arrays.

[0094] Figure 10 This is a schematic perspective view of a complete base station antenna 100 configured according to an embodiment of the present invention. The base station antenna 100 corresponds to the base station antenna 90, wherein a weatherproof dielectric cover (antenna radome) 101 is added to protect the components of the base station antenna 100 from environmental factors such as wind and rain.

[0095] Figure 11 Is with Figure 10 The base station antenna 100 is similar (except for the one used to generate...). Figure 11 The diagram shows a simulated azimuth pattern of a base station antenna (including a single radiating element). The cylindrical RF lens used in the simulation has a diameter of 200 mm and is oriented to extend vertically along its axis. Figure 11 As shown, the generated antenna beam has a measurement azimuth beamwidth of 23.1° at 3.7 GHz, a measurement directivity of 17.2 dB, a maximum sidelobe level of -20 dB in the azimuth plane, and a cross-polarization discrimination of 26 dB on the beam axis (i.e., in the aiming direction).

[0096] Figure 12 It is based on Figure 7 A diagram showing the measured elevation radiation pattern of a base station antenna, which comprises a linear array with two radiating elements. (See diagram for reference.) Figure 12 As shown, when fed with a 3.7 GHz RF signal, the base station antenna has a 3-dB beamwidth of 23.2°, a directivity of 17.2 dB, and a sidelobe level 20.1 dB lower than the peak gain.

[0097] Figure 13A This is a schematic top view of a base station antenna 100 comprising three linear arrays 101, 102, and 103 of radiating elements, arranged at different azimuth angles relative to the axis of a vertically oriented cylindrical RF lens. Each linear array 101, 102, and 103 may include one or more radiating elements arranged in a corresponding vertically extending column. Figure 13B , Figure 13C and Figure 13D A simulated wavefront is shown as the RF signal radiated by each linear array 101, 102, 103 of the radiating elements propagates through a cylindrical RF lens. It can be seen that as the wave propagates through the cylindrical RF lens, the curved wavefront emitted by the linear arrays straightens.

[0098] In a preferred embodiment, the reflectors 104, 105, 106 behind each linear array 101, 102, 103 of the radiating element are non-planar, wherein the shapes of the reflectors 104, 105, 106 are arranged to reduce the coupling between adjacent linear arrays 101, 102, 103.

[0099] What will be understood is... Figure 13A The base station antenna will operate as a sector-segmented antenna that divides the coverage area of ​​the antenna into multiple (three in this case) sectors in the azimuth plane, wherein the antenna generates a separate pair of antenna beams (due to the use of dual-polarized radiating elements) to provide service to each sub-sector of the coverage area.

[0100] Figure 14 It is a diagram showing the process of... Figure 13A The diagram shows the azimuth radiation patterns of three independent antenna beams generated by three linear arrays of a base station antenna. In this example, the 3dB azimuth beamwidth of each beam is approximately 22°, all sidelobes are at least 19dB lower than the main beam, and the main beam is separated by an azimuth angle of approximately 45°.

[0101] Figure 15 yes Figure 7 A schematic perspective view of the cylindrical RF lens included in the base station antenna, and Figure 15 It also includes calculations of the volume consumed by the dielectric member 121 and the flexible dielectric substrate 122 of the radial assembly, compared to the total volume of the cylinder 123 defined by the cylindrical RF lens. These calculations show that... Figure 7 The cylindrical RF lens 120 included in the base station antenna is approximately 89% space or air, which translates to a very lightweight lens.

[0102] Figures 16A-16D These are front, top, side, and perspective views of a base station antenna including a hybrid cylindrical RF lens according to a further embodiment of the present invention. As shown, the hybrid cylindrical RF lens includes a first cylindrical RF lens and a second and a third semi-cylindrical RF lens mounted on opposite sides of the first cylindrical RF lens. The cylindrical RF lens can be any cylindrical RF lens discussed above, and the semi-cylindrical RF lens can be half of any cylindrical RF lens discussed above.

[0103] Figure 17 yes Figures 16A-16D A diagram showing the orientation of the base station antennas. (Example) Figure 17 As shown, the generated antenna beam has a “square” beam shape in the azimuth plane.

[0104] Figure 18 This is a top view of a dual-beam (i.e., sector-segmented) base station antenna according to an embodiment of the present invention, the dual-beam base station antenna comprising... Figures 16A-16D The base station antenna uses the same hybrid cylindrical RF lens. For example... Figure 18 As shown, the first linear array and the second linear array of radiating elements (in) Figure 18 Only the top radiating element in each linear array (visible only in the image) is mounted to illuminate the RF lens structure. Each linear array is angled towards the desired coverage area. For example, Figure 18 The base station antenna can, for example, be used to form two antenna beams (per polarization) for corresponding sub-sectors of a sector in a cell covering a cellular communication network.

[0105] Figure 19A and Figure 19BThis is a schematic perspective view of a dual-band antenna according to an embodiment of the present invention, the dual-band antenna including a cylindrical RF lens. Figures 19A-19B As shown, radiating elements operating in two different frequency bands can be mounted on a reflector and positioned such that the RF energy they radiate will pass through a cylindrical RF lens, which can be any of the aforementioned cylindrical RF lenses according to embodiments of the present invention. Figure 19A In one embodiment, two radiating elements are stacked on top of the reflector plate. Figure 19B In one embodiment, a higher frequency band cross-dipole radiating element is mounted at the center of a lower frequency band box-shaped dipole radiating element.

[0106] The above about Figures 6-19B The cylindrical RF lenses discussed are hybrid cylindrical RF lenses because they employ standard dielectric materials (e.g., Figure 6 The radial component 61 and metamaterial structures (e.g., dielectric substrate 64 on which conductive scattering elements 48 are formed) are used to focus RF radiation incident on the cylindrical RF lens. The additional focusing provided by the standard dielectric material allows for a reduction in the density of conductive scattering elements 48 included on the concentric cylindrical dielectric sheet, while still providing sufficient focusing, which improves the cross-polarization discrimination performance of the antenna.

[0107] Figure 20 This is a side perspective view of the internal components of a base station antenna 200 according to a further embodiment of the present invention. The base station antenna 200 includes three reflectors 210 and three linear arrays 220 of radiating elements 222 (in... Figure 20 (Only one linear array is visible in the image) and a cylindrical RF lens 230. A support frame (not shown) may also be provided to mount the linear array 220 of radiating elements 222 to the cylindrical RF lens 230. As shown, each reflector 210 includes a planar sheet 212 of metal, and the radiating elements 222 are mounted to extend forward from the corresponding planar sheet 212. The edges of each planar sheet 212 are bent forward to help narrow the radiation pattern emitted by the individual radiating elements 222 and increase the isolation between adjacent radiating elements 222.

[0108] Radiation element 222 may include, for example, a tilted - / +45° crossed dipole radiation element. Furthermore, while each linear array 210 is shown as including a single radiation element 222, it will be understood that in other embodiments, the linear array 210 may each include two or more radiation elements 222 to reduce the beamwidth of the resulting antenna beam in the elevation plane.

[0109] The cylindrical RF lens 230 differs from the cylindrical RF lens described above according to an embodiment of the present invention in that the cylindrical RF lens 230 includes a group of first layer plates 240 and a group of second layer plates 250, the first layer plates 240 having conductive scattering elements 244 formed thereon. Each first layer plate 240 extends radially outward from the axis 232 of the cylinder defined by the cylindrical RF lens 230. Each first layer plate 240 includes a planar rectangular dielectric substrate 242 having a plurality of conductive scattering elements 244 on at least one main surface of the planar rectangular dielectric substrate 242. The conductive scattering elements 244 can be arranged in rows and columns on the dielectric substrate 242, the rows and columns extending along the polarization plane of the RF radiation emitted by the dipole radiator of the radiating element 222, and thus the conductive scattering elements 244 can be arranged as described above. Figure 5A The positioning is shown in the figure. The cylindrical RF lens 230 also includes a cylindrical support member 234 having a plurality of longitudinal slots 236 formed therein. The inner end of each first layer plate 240 can be received in a corresponding slot 236 in the slots 236.

[0110] The cylindrical RF lens 230 also includes a group of second layer plates 250. Each second layer plate 250 extends in a corresponding plane perpendicular to a plane defined by the main surface of the first layer plate 240. Each second layer plate 250 may intersect at least two first layer plates 230. In some embodiments, each second layer plate 250 may have a planar semi-circular shape and may intersect approximately half of the first layer plate 240. Each second layer plate 250 may include a planar dielectric substrate 252 having a plurality of grooves formed therein that cooperate with corresponding grooves in the dielectric substrate 242 of the first layer plate 240, such that the first layer plate 240 and the second layer plate 250 can be coupled together. Figure 20 Interconnected in the manner shown.

[0111] In some embodiments, at least one and up to all of the second layer plates 250 may be without conductive scattering elements. In such embodiments, each second layer plate 250 may comprise only a dielectric substrate 252, such as a plastic plate. In embodiments in which the second layer plates 250 do not include any conductive scattering elements, it is self-evident that the density of conductive scattering elements included in the second layer plates 250 is less than the density of conductive scattering elements included in the first layer plates 240 (because each first layer plate 240 includes conductive scattering elements 244, while the second layer plates 250 do not). In other embodiments, at least one second layer plate 250 may comprise a dielectric substrate 252 having at least one conductive scattering element (not shown) thereon. In such embodiments, the density of conductive scattering elements 244 on at least one first layer plate 240 exceeds the density of conductive scattering elements (not shown) on at least one second layer plate 250, and in some cases, the density of conductive scattering elements on each first layer plate 240 may exceed the density of conductive scattering elements (not shown) on at least one second layer plate 250, and may exceed the corresponding density of conductive scattering elements (not shown) on all second layer plates 250.

[0112] like Figure 20 As shown, in some embodiments, the number of first layer plates 240 may exceed the number of second layer plates 250. For example, the number of first layer plates 240 may be at least two times, at least three times, at least four times, or at least five times the number of second layer plates 250. Moreover, the thickness of at least one second layer plate 250 may exceed the thickness of at least one first layer plate 240, and may exceed the thickness of all first layer plates 240. The first layer plates 240 and the second layer plates 250 may define a cylinder.

[0113] The cylindrical RF lens 230 of the base station antenna 200 implements conductive scattering elements 244 only on the radially extending dielectric substrate 242 of the first layer 240, and uses the ordinary dielectric substrate 252 of the second layer 250 (i.e., the dielectric substrate on which the conductive scattering elements are not present) as the focusing medium in the horizontal plane. This arrangement has been found to significantly reduce coupling between adjacent linear arrays 220 of radiating elements 222. The number, thickness, and / or dielectric constant of the second layer 250 can be adjusted to achieve adequate focusing in the horizontal plane. It has been found that a small number of second layer 250s can be used, especially if they are thickened and / or formed of a high dielectric constant material. This simplifies the construction of the cylindrical RF lens 230 and reduces its cost. As shown, the second layer 250 does not necessarily need to be arranged symmetrically. In the depicted embodiment, an additional dielectric second layer 250 is provided near the top of the cylindrical RF lens 230. This can help, for example, provide a downtilt to the generated antenna beam in the elevation plane.

[0114] Still referencing Figure 20 According to a further embodiment of the present invention, a base station antenna is provided, comprising a cylindrical RF lens 230 and a radiating element 222. The cylindrical RF lens 230 includes a group of first layer plates 240, each first layer plate 240 extending radially outward from an axial direction. The radiating element 222 is configured to radiate toward the cylindrical RF lens 230. Each first layer plate 240 includes a planar dielectric substrate 242 and a plurality of conductive scattering elements 244 on at least one main surface of the planar dielectric substrate 242. The cylindrical RF lens 230 may further include a group of second layer plates 250, each second layer plate 250 intersecting at least two first layer plates 240. In some embodiments, each second layer plate 250 extends in a corresponding plane parallel to a plane defined by the main surface of each first layer plate 240.

[0115] In some embodiments, a first number of first layers 240 in a group of first layers 240 exceeds a second number of second layers 250 in a group of second layers 250. In some embodiments, the thickness of at least one second layer 250 exceeds the thickness of at least one first layer 240. In some embodiments, the thickness of at least one second layer 250 exceeds the thickness of each first layer 240.

[0116] In some embodiments, each second layer 250 includes a dielectric substrate 252, which may optionally have one or more conductive scattering elements on at least one of its main surfaces, and wherein the density of conductive scattering elements on at least one first layer 240 exceeds the density of conductive scattering elements on at least one second layer 250. In some embodiments, the corresponding density of conductive scattering elements on each first layer 240 exceeds the density of conductive scattering elements on at least one second layer 250.

[0117] In some embodiments, the cylindrical RF lens 230 further includes a cylindrical support element 234 having a plurality of slots 236, wherein the edge of each first layer plate 240 is received in a corresponding slot 236 in the slots 236 of the cylindrical support element.

[0118] Still referencing Figure 20 According to other embodiments of the present invention, a base station antenna is provided, comprising a cylindrical RF lens and a radiating element. The cylindrical RF lens includes a first layer group and a second layer group, each first layer extending in a corresponding vertical plane among a plurality of vertical planes, and each second layer extending in a corresponding horizontal plane among a plurality of horizontal planes. The radiating element is configured to radiate toward the RF lens. Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0119] In another embodiment, a base station antenna is provided, comprising a cylindrical RF lens 230 and a radiating element 222. The cylindrical RF lens 230 has a central axis, and the radiating element 222 is configured to radiate toward the cylindrical RF lens 230. The cylindrical RF lens 230 includes a group of first plates 240 and a group of second plates 250, each first plate 240 extending radially outward from the central axis, and each second plate 250 extending perpendicular to the central axis. A first number of first plates 240 in the group of first plates 240 exceeds a second number of second plates 250 in the group of second plates 250.

[0120] Still referencing Figure 20 In another embodiment, a base station antenna is provided, comprising a cylindrical RF lens 230 and a radiating element 222 configured to radiate toward the cylindrical RF lens 230. The cylindrical RF lens 230 includes a group of first plates 240 and a group of second plates 250, each first plate 240 extending in a corresponding vertical plane among a plurality of vertical planes, and each second plate 250 extending in a corresponding horizontal plane among a plurality of horizontal planes. Each first plate 240 includes a planar dielectric substrate 242 and a plurality of conductive scattering elements 244 on at least one main surface of the planar dielectric substrate 222, and each second plate 250 includes a dielectric substrate 252, and the density of conductive scattering elements 244 on at least one first plate 240 exceeds the density of conductive scattering elements on at least one second plate 250.

[0121] The electrical performance of the antenna embodying the present invention is not limited to the examples provided. At least the following parameters can be varied according to requirements for operating frequency, bandwidth, gain, beamwidth, sidelobe level, and cross-polarization performance: the outer diameter of the lens, the number and spacing of the concentrically arranged conductive scattering elements, the configuration of the conductive scattering elements and their mutual arrangement, and the position and beamwidth of the radiating elements.

[0122] In some embodiments, such as if the RF lens needs to support multiple radiating elements oriented in different radial directions, the concentric cylinder supporting the conductive scattering elements is preferably a circular cylinder; however, for RF lenses designed to form a beam in a single radial direction, an elliptical cylinder may preferably be used.

[0123] In some embodiments, the diameter of the concentric dielectric cylinder supporting the conductive scattering element may be increased in equal increments. In other embodiments, the increments may be unequal.

[0124] In some embodiments, the conductive scattering elements on each concentric dielectric cylindrical shell may have the same configuration, while in other embodiments, the configuration between the shells may be different.

[0125] In some embodiments, the spacing between the conductive scattering elements on each concentric dielectric cylindrical shell may be the same, while in other embodiments, the spacing between the shells may be different.

[0126] In some embodiments, the dielectric shell and / or first layer of the base station antenna 200 having conductive scattering elements thereon can be implemented using a thin printed circuit board (e.g., FR4) using standard printed circuit technology. A layer thickness of 0.254 mm (10 mil) has been found to be convenient.

[0127] In some embodiments, the dielectric plate 13 may have a constant thickness, while in other embodiments, the thickness of the dielectric plate may vary with the distance from the longitudinal axis of the lens.

[0128] In some embodiments, the plurality of dielectric plates 13 may be formed as a single entity, for example by injection molding, while in other embodiments, it may be formed as an assembly of individual plates that can be supported by a central axis dielectric member.

[0129] In some embodiments, the radiating element may be in the form of a crossed dipole with a reflector, while in other embodiments, the radiating element may be any other form of wide-beam unidirectional element, including but not limited to patches or horns.

[0130] The axial length of the cylindrical lens can be extended to allow for use in combination with an extended array of radiating elements.

[0131] It will be understood that many modifications can be made to the above-described example base station antenna without departing from the scope of the invention. For example, the operating frequency, bandwidth, gain, beamwidth, sidelobe level, and cross-polarization discrimination can differ from the examples shown herein, such as the outer diameter of the RF lens, the number and spacing of the layers, the number and spacing of the conductive scattering elements, the configuration of the scattering elements and their arrangement, and the positioning and beamwidth of the radiating elements.

[0132] As some examples of possible variations, in some embodiments the conductive scattering elements may have the same configuration on each layer, while in other embodiments the configuration between the shells may be different. In some embodiments, the spacing between the conductive scattering elements on each layer may be the same, while in other embodiments the spacing between the layers may be different. In some embodiments, the conductive scattering elements can be formed on an FR4 substrate by using a printed circuit board to implement the layers. A dielectric substrate thickness of 0.76 mm (30 mil) has been found to be convenient.

[0133] This disclosure provides the following examples:

[0134] 1. An antenna, comprising:

[0135] Cylindrical RF lens; and

[0136] A radiating element, arranged to illuminate the cylindrical RF lens, wherein the cylindrical RF lens comprises:

[0137] Multiple substantially planar dielectric plates, each extending in a corresponding radial direction and having a first edge adjacent to the axis of the cylindrical RF lens, wherein the angles between the radial directions are equal, and

[0138] Multiple concentric cylindrical dielectric shells, each supporting multiple conductive scattering elements, are arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0139] 2. The antenna according to claim 1, wherein the cylindrical RF lens includes more dielectric plates than the cylindrical dielectric shell.

[0140] 3. The antenna according to claim 1, wherein each dielectric plate includes a plurality of slots extending parallel to the axis of the cylindrical RF lens.

[0141] 4. The antenna according to claim 3, wherein the cylindrical dielectric shell is received in a slot in the dielectric plate.

[0142] 5. The antenna according to claim 1, wherein the dielectric plate has no conductive scattering element.

[0143] 6. The antenna according to claim 1, wherein the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell.

[0144] 7. The antenna according to claim 1, wherein the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell.

[0145] 8. The antenna according to claim 1, wherein the average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating frequency band of the radiating element.

[0146] 9. The antenna according to claim 1, wherein the radiating element is a first radiating element, and the antenna further comprises a second radiating element, wherein the first radiating element and the second radiating element are stacked along an axis extending parallel to the axis of the cylindrical RF lens.

[0147] 10. The antenna according to claim 1, wherein the radiating element is a first radiating element, and the antenna further includes a second radiating element, wherein the first radiating element and the second radiating element are spaced apart from each other in a plane perpendicular to the axis of the cylindrical RF lens.

[0148] 11. A base station antenna, comprising:

[0149] Radiating elements; and

[0150] A cylindrical RF lens comprising a plurality of concentric cylindrical dielectric shells, wherein each dielectric shell supports a plurality of conductive scattering elements arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0151] 12. The base station antenna of claim 11, wherein the cylindrical RF lens further comprises a plurality of dielectric plates, each dielectric plate extending in a respective radial direction and having a first edge adjacent to the axis of the cylindrical RF lens.

[0152] 13. The base station antenna according to 12, wherein the angles between the radial directions are equal.

[0153] 14. The base station antenna according to claim 12, wherein the cylindrical RF lens includes more dielectric plates than the cylindrical dielectric shell.

[0154] 15. The base station antenna of claim 12, wherein each dielectric plate includes a plurality of slots extending parallel to the axis of the cylindrical RF lens.

[0155] 16. The base station antenna according to 15, wherein the cylindrical dielectric shell is received in a slot in the dielectric plate.

[0156] 17. The base station antenna according to 12, wherein the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell.

[0157] 18. The base station antenna according to 17, wherein the dielectric plate has no conductive scattering element.

[0158] 19. The base station antenna according to claim 17, wherein the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell.

[0159] 20. The base station antenna according to claim 11, wherein the average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating frequency band of the radiating element.

[0160] 21. A base station antenna, comprising:

[0161] Radiating elements; and

[0162] Cylindrical RF lens, the cylindrical RF lens comprising:

[0163] Cylindrical support element, and

[0164] Multiple planar dielectric plates extend radially outward from the cylindrical support element.

[0165] 22. The base station antenna according to 21, wherein the cylindrical support element includes a plurality of slots extending parallel to the axis of the cylindrical RF lens.

[0166] 23. The base station antenna according to 22, wherein each planar dielectric plate is received in a corresponding slot in the slot.

[0167] 24. The base station antenna according to 21, wherein the angles between adjacent planar dielectric plates in the planar dielectric plate are equal.

[0168] 25. The base station antenna of claim 21, wherein the cylindrical RF lens further comprises a plurality of concentric cylindrical dielectric shells, wherein each dielectric shell supports a plurality of conductive scattering elements.

[0169] 26. The base station antenna according to 25, wherein the conductive scattering elements are arranged in rows and columns, the rows and columns being aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

[0170] 27. The base station antenna of claim 25, wherein the cylindrical RF lens comprises more dielectric plates than the cylindrical dielectric shell.

[0171] 28. The base station antenna of claim 25, wherein each dielectric plate includes a plurality of slots extending parallel to the axis of the cylindrical RF lens.

[0172] 29. The base station antenna according to 28, wherein a cylindrical dielectric shell is received in a slot in a dielectric plate.

[0173] 30. The base station antenna according to claim 25, wherein the dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell.

[0174] 31. The base station antenna according to claim 21, wherein the dielectric plate has no conductive scattering element.

[0175] 32. The base station antenna according to claim 25, wherein the thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell.

[0176] 33. The base station antenna according to claim 25, wherein the average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating frequency band of the radiating element.

[0177] 34. A base station antenna, comprising:

[0178] A cylindrical RF lens, the cylindrical RF lens comprising a first layer assembly, each first layer extending radially outward from an axial direction; and

[0179] A radiating element, configured to radiate toward the cylindrical RF lens.

[0180] Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0181] 35. According to the base station antenna of 34, the cylindrical RF lens further includes a second layer plate group, each second layer plate intersecting with at least two first layer plates.

[0182] 36. The base station antenna according to 35, wherein each second layer plate extends in a corresponding plane, the corresponding plane being parallel to the plane defined by the main surface of each first layer plate.

[0183] 37. The base station antenna according to 35, wherein the first number of the first layer plates in the first layer plate group exceeds the second number of the second layer plates in the second layer plate group.

[0184] 38. The base station antenna according to 35, wherein the thickness of at least one second layer plate exceeds the thickness of at least one first layer plate.

[0185] 39. The base station antenna according to 35, wherein the thickness of at least one second layer plate exceeds the thickness of each first layer plate.

[0186] 40. The base station antenna of claim 35, wherein each second layer plate includes a dielectric substrate, the dielectric substrate optionally having one or more conductive scattering elements on at least one major surface thereon, and wherein the density of conductive scattering elements on at least one first layer plate exceeds the density of conductive scattering elements on at least one second layer plate.

[0187] 41. The base station antenna according to 40, wherein the density of the conductive scattering elements on each first layer plate exceeds the density of the conductive scattering elements on at least one second layer plate.

[0188] 42. The base station antenna according to claim 35, wherein each first layer plate includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate, and at least one second layer plate has no conductive scattering elements.

[0189] 43. The base station antenna according to 34, wherein the first layer plate is a rectangular layer plate.

[0190] 44. The base station antenna of claim 34, wherein the RF lens further comprises a cylindrical support element having a plurality of slots, wherein the edge of each first layer plate is received in a corresponding slot in the slot of the cylindrical support element.

[0191] 45. A base station antenna, comprising:

[0192] Cylindrical RF lens, the cylindrical RF lens comprising:

[0193] The first layer of panels, each extending in a corresponding vertical plane among multiple vertical planes.

[0194] The second layer assembly, each second layer extending in a corresponding horizontal plane among a plurality of horizontal planes; and

[0195] A radiating element, configured to radiate toward the cylindrical RF lens.

[0196] Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0197] 46. ​​The base station antenna according to 45, wherein the first number of the first layer plates in the first layer plate group exceeds the second number of the second layer plates in the second layer plate group.

[0198] 47. The base station antenna according to 45, wherein the thickness of at least one second layer plate exceeds the thickness of at least one first layer plate.

[0199] 48. The base station antenna according to 45, wherein the density of conductive scattering elements on at least one first layer plate exceeds the density of conductive scattering elements on at least one second layer plate.

[0200] 49. The base station antenna according to 45, wherein at least one second layer plate has no conductive scattering element.

[0201] 50. A base station antenna, comprising:

[0202] A cylindrical RF lens having a central axis, the cylindrical RF lens comprising:

[0203] The first layer of panels, each extending radially outward from the central axis.

[0204] The second layer of panels, each of which is perpendicular to the central axis; and

[0205] A radiating element, configured to radiate toward the cylindrical RF lens.

[0206] The first number of first-layer plates in the first layer group exceeds the second number of second-layer plates in the second layer group.

[0207] 51. The base station antenna according to claim 50, wherein the first number is at least three times the second number.

[0208] 52. The base station antenna according to claim 50, wherein the thickness of at least one second layer plate exceeds the thickness of at least one first layer plate.

[0209] 53. The base station antenna according to claim 50, wherein each first layer plate includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate.

[0210] 54. The base station antenna according to claim 53, wherein the density of conductive scattering elements on at least one first layer plate exceeds the density of conductive scattering elements on at least one second layer plate.

[0211] 55. The base station antenna according to 53, wherein at least one second layer plate has no conductive scattering element.

[0212] 56. A base station antenna, comprising:

[0213] Cylindrical RF lens, the cylindrical RF lens comprising:

[0214] The first layer of panels, each extending in a corresponding vertical plane among multiple vertical planes.

[0215] The second layer assembly, each second layer extending in a corresponding horizontal plane among a plurality of horizontal planes; and

[0216] A radiating element, configured to radiate toward the cylindrical RF lens.

[0217] Each first layer includes a planar dielectric substrate and a plurality of conductive scattering elements on at least one main surface of the planar dielectric substrate, and each second layer includes a dielectric substrate, and

[0218] The density of conductive scattering elements on at least one first layer plate exceeds the density of conductive scattering elements on at least one second layer plate.

[0219] 57. The base station antenna according to claim 56, wherein the first number of first layer plates in the first layer plate group exceeds the second number of second layer plates in the second layer plate group.

[0220] 58. The base station antenna according to claim 56, wherein the thickness of at least one second layer plate exceeds the thickness of at least one first layer plate.

[0221] 59. The base station antenna according to claim 56, wherein the density of conductive scattering elements on at least one first layer plate exceeds the density of conductive scattering elements on all second layer plates.

[0222] 60. The base station antenna according to claim 42, wherein at least one second layer plate has no conductive scattering element.

[0223] Embodiments of the invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are illustrated. However, the 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 complete and full, and will fully convey the scope of the invention to those skilled in the art. The same numerals refer to the same elements throughout the text.

[0224] In this text, if an axis extending in a given direction (e.g., forward direction) passes through two elements, then the first element overlaps with the second element in that direction.

[0225] In this article, the term “basic” means a change of less than 10%, unless otherwise stated.

[0226] 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 used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0227] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element, or there may be intermediate elements present. In contrast, when an element is referred to as being "directly on" another element, there are no intermediate elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intermediate elements present. Other terms used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.).

[0228] 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" ("a") and "the" ("the") are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprises" and / or "includes" are used herein, it indicates the presence of the stated features, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

[0229] All aspects and elements of the embodiments disclosed above can be combined in any way and / or combined with aspects or elements of other embodiments to provide multiple additional embodiments.

Claims

1. An antenna, comprising: Cylindrical RF lens; as well as A radiating element, arranged to illuminate the cylindrical RF lens, wherein the cylindrical RF lens comprises: Multiple substantially planar dielectric plates, each extending in a corresponding radial direction and having a first edge adjacent to the axis of the cylindrical RF lens, wherein the angles between the radial directions are equal, and Multiple concentric cylindrical dielectric shells, each supporting multiple conductive scattering elements, are arranged in rows and columns aligned to extend at angles of 45° and -45° relative to the axis of the cylindrical RF lens.

2. The antenna according to claim 1, wherein, The cylindrical RF lens includes more dielectric plates than a cylindrical dielectric shell.

3. The antenna according to claim 1, wherein, Each dielectric plate includes multiple slots extending parallel to the axis of the cylindrical RF lens.

4. The antenna according to claim 3, wherein, The cylindrical dielectric shell is received in a slot in the dielectric plate.

5. The antenna according to claim 1, wherein, The dielectric plate does not have conductive scattering elements.

6. The antenna according to claim 1, wherein, The dielectric constant of at least one dielectric plate exceeds the dielectric constant of at least one cylindrical dielectric shell.

7. The antenna according to claim 1, wherein, The thickness of at least one dielectric plate exceeds the thickness of at least one cylindrical dielectric shell.

8. The antenna according to claim 1, wherein, The average spacing between adjacent conductive scattering elements is at least 0.2 times the wavelength of the center frequency corresponding to the operating frequency band of the radiating element.

9. The antenna according to claim 1, wherein, The radiating element is a first radiating element, and the antenna further includes a second radiating element, wherein the first radiating element and the second radiating element are stacked along an axis extending parallel to the axis of the cylindrical RF lens.

10. The antenna according to claim 1, wherein, The radiating element is a first radiating element, and the antenna further includes a second radiating element, wherein the first radiating element and the second radiating element are spaced apart from each other in a plane perpendicular to the axis of the cylindrical RF lens.

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