Radiating element with stealth feed shank and / or stealth feed cable

Abstract

A radiating element includes a feed shank and a radiator mounted on the feed shank. The feed handle includes a signal line, a first ground line, and a ring-based metamaterial resonator.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 463,681, filed May 3, 2023, and U.S. Provisional Application Serial No. 63 / 528,689, filed July 25, 2023, the entire contents of each of which are incorporated herein by reference. Background Technology

[0003] The present invention relates generally to radio communications, and more specifically, to base station antennas for cellular communication systems and to radiating elements for such base station antennas.

[0004] Cellular communication systems are well known in the art. In a cellular communication system, a geographical area is divided into a series of areas called “cells” served by corresponding base stations. Each base station may include one or more base station antennas configured to provide bidirectional radio frequency (“RF”) communication with fixed and mobile users within the cell served by the base station. Typically, base station antennas are mounted on towers or other elevated structures, where a radiation pattern (also referred to herein as an “antenna beam”) is generated by the outward-pointing base station antennas.

[0005] A common base station configuration is a three-sector configuration, where the cell is divided into three 120° sectors in the azimuth (horizontal) plane. A separate base station antenna provides coverage (service) for each sector. Typically, each base station antenna will include multiple vertically extending columns of radiating elements, which operate using, for example, second-generation (“2G”), third-generation (“3G”), or fourth-generation (“4G”) cellular network protocols. These vertically extending columns of radiating elements are often referred to as “linear arrays” and can be either straight columns or columns of radiating elements with some elements horizontally staggered. Most modern base station antennas include both “low-band” linear arrays of radiating elements supporting service in some or all of the 617-960MHz band and “mid-band” linear arrays of radiating elements supporting service in some or all of the 1427-2690MHz band. These linear arrays are typically formed using dual-polarized radiating elements, which allows each linear array to transmit and receive RF signals simultaneously with two orthogonal polarizations.

[0006] Each of the linear arrays described above is coupled to two ports of a radio device (one port polarized per port). The RF signal emitted by the linear array is transmitted from the radio device ports to the antenna, where it is split into multiple sub-components. Each sub-component is fed to a corresponding subset of radiating elements in the linear array (typically one to three radiating elements per sub-component). The sub-components of the RF signal are transmitted through the radiating elements to generate an antenna beam covering a generally fixed coverage area (such as a sector of a cell). (E.g., using phase delay lines) The relative phases of the sub-components of the RF signal are set such that the individual antenna beams generated by each subset of the radiating elements are constructively combined to reduce the half-power beamwidth (“HPBW”) of the antenna beam generated in the elevation (vertical) plane. Because the aforementioned 2G / 3G / 4G linear arrays generate static antenna beams, they are often referred to as “passive” linear arrays.

[0007] Most cellular operators are currently upgrading their networks to support fifth-generation (“5G”) cellular services. A key component of 5G cellular services is the use of what is known as “active” beamforming arrays, which work in conjunction with “active” beamforming radios to dynamically adjust the size, shape, and pointing direction of the antenna beam generated by the active beamforming array. These active beamforming arrays consist of multiple rows of radiating elements, with eight rows being the most common. Active beamforming arrays are typically formed using “high-frequency” radiating elements that operate in higher frequency bands (e.g., some or all of the 3.1–4.2 GHz band and / or 5.1–5.8 GHz band), but active beamforming arrays operating in the higher portion of the mid-frequency range (e.g., 2300–2690 MHz) can also be provided. Each row of radiating elements in such an active beamforming array is typically coupled to a corresponding port of a beamforming radio. The beamforming radio can be a standalone device or can be integrated with an active antenna array. Beamforming radios can dynamically adjust the amplitude and phase of sub-components of an RF signal fed to each port of the radio to generate an antenna beam with a narrowed beamwidth (and therefore higher antenna gain) in the azimuth plane. These narrowed antenna beams can be electronically redirected in the azimuth plane by correctly selecting the amplitude and phase of the RF signal sub-components.

[0008] To avoid having to increase the number of antennas at cell sites, the aforementioned 5G antennas typically include passive linear arrays supporting traditional 2G, 3G, and / or 4G cellular services. In a popular solution, a 5G active antenna module (i.e., a module including an active beamforming array and associated beamforming radios) is mounted on the rear surface of a passive base station antenna comprising multiple 2G, 3G, and / or 4G passive linear arrays. Openings are provided in the reflectors of the passive base station antennas so that the antenna beam generated by the active beamforming array can be transmitted through the passive base station antenna. Typically, some radiating elements of the 2G / 3G / 4G passive linear arrays are mounted in front of the radiating elements of the beamforming array. This antenna design is advantageous because the active antenna module can be removable, so as enhanced 5G capabilities are developed, cellular operators can replace the original active antenna module with an upgraded active antenna module without having to replace the passive base station antenna. In this paper, the combination of a passive base station antenna with an active antenna module mounted thereon is referred to as a "passive / active antenna system". Summary of the Invention

[0009] According to an embodiment of the present invention, a radiating element is provided, the radiating element comprising: a feed stem having a signal line, a first ground line and a ring-based metamaterial resonator; and a radiator mounted on the feed stem.

[0010] In some embodiments, the ring-based metamaterial resonator overlaps with the first ground wire. In some embodiments, the ring-based metamaterial resonator includes a complementary split-ring resonator or a split-ring resonator.

[0011] In some embodiments, the feed handle includes a first plurality of ring-based metamaterial resonators, wherein the ring-based metamaterial resonator is one of the first plurality of ring-based metamaterial resonators, and the first plurality of ring-based metamaterial resonators overlap with at least 50% of the first ground wire. In some embodiments, the feed handle further includes a second ground wire and a second plurality of ring-based metamaterial resonators overlapping with at least 50% of the second ground wire. In some embodiments, the feed handle includes a feed handle printed circuit board having a dielectric substrate having a first metallization pattern and a second metallization pattern on its opposing first and second main surfaces, wherein the signal line and the ring-based metamaterial resonator are at least a portion of the first metallization pattern, and the first ground wire and the second ground wire are at least a portion of the second metallization pattern. In some embodiments, the signal line includes a first segment overlapping the first ground wire, a third segment overlapping the second ground wire, and a second segment connecting the first segment to the third segment. In some embodiments, the signal line is between the first plurality of ring-based metamaterial resonators, and the second plurality of ring-based metamaterial resonators overlap with the second ground wire.

[0012] In some embodiments, the feed handle includes a feed handle printed circuit board having: a first dielectric substrate having a first metallization pattern; a second dielectric substrate having a third metallization pattern; and a second metallization pattern positioned between the first dielectric substrate and the second dielectric substrate, wherein the ring-based metamaterial resonator is part of the first metallization pattern, the signal line is at least a part of the second metallization pattern, and the first ground line is part of the third metallization pattern.

[0013] In some embodiments, the radiator is mounted on the front end of the feed handle, and the ring-based metamaterial resonator overlaps with a portion of the first ground wire positioned in front of the signal line.

[0014] In some embodiments, any of the above-described radiating elements may be included in a base station antenna, which further includes a second radiating element configured to operate at a higher operating frequency band than the first radiating element. The ring-based metamaterial resonator is configured to operate as a bandpass filter having a passband that includes at least a portion of the higher operating frequency band. In some embodiments, the first radiating element may be mounted in front of the second radiating element.

[0015] According to another embodiment of the invention, radiating elements are provided, each including a radiator and a feed stem printed circuit board, the feed stem printed circuit board including at least: a first dielectric substrate; a first metallization pattern extending in a longitudinal direction on a first outer surface of the dielectric substrate; and a second metallization pattern including a plurality of ring-based metamaterial resonators.

[0016] In some embodiments, the first metallization pattern includes a first ground wire and a second ground wire. In some embodiments, the second metallization pattern further includes a signal line positioned between a first ring-based metamaterial resonator and a second ring-based metamaterial resonator among the plurality of ring-based metamaterial resonators. In some embodiments, the plurality of ring-based metamaterial resonators includes a first plurality of ring-based metamaterial resonators and a second plurality of ring-based metamaterial resonators. In some embodiments, the first plurality of ring-based metamaterial resonators overlap with the first ground wire.

[0017] In some embodiments, the plurality of ring-based metamaterial resonators include a plurality of complementary split-ring resonators or a plurality of split-ring resonators.

[0018] In some embodiments, the second metallization pattern is on the second outer surface of the first dielectric substrate.

[0019] In some embodiments, the feed stem printed circuit board further includes a second dielectric substrate, wherein the second metallization pattern is on the outer surface of the second dielectric substrate, and the feed stem further includes a signal line, the signal line being part of a third metallization pattern positioned between the first dielectric substrate and the second dielectric substrate. In some embodiments, the signal line includes a first segment overlapping the first ground line, a third segment overlapping the second ground line, and a second segment connecting the first segment to the third segment. In some embodiments, the plurality of ring-based metamaterial resonators includes a first plurality of ring-based metamaterial resonators and a second plurality of ring-based metamaterial resonators, wherein the first plurality of ring-based metamaterial resonators overlaps the first ground line, and the second plurality of ring-based metamaterial resonators overlap the second ground line.

[0020] In some embodiments, the signal line, together with the first ground line and the second ground line, includes an RF feed line.

[0021] According to other embodiments of the present invention, a base station antenna is provided, the base station antenna comprising: a first radiating element configured to operate in a first operating frequency band; and a second radiating element configured to operate in a second operating frequency band containing a higher frequency than the first operating frequency band. A feed stem of the first radiating element includes a radio frequency (“RF”) feed line, the RF feed line including a filter having a passband in the first operating frequency band and a stopband in the second operating frequency band.

[0022] In some embodiments, the filter includes an inductor connected in series with a first capacitor. In some embodiments, the RF feed includes a signal line and a first ground line, wherein the inductor is part of the first ground line. In some embodiments, the inductor includes a tortuous conductive trace having an average width less than half the average width of the remainder of the first ground line. In some embodiments, the filter further includes a second capacitor connected in parallel with the series combination of the inductor and the first capacitor.

[0023] In some embodiments, the filter is implemented on a first feed stem printed circuit board of the feed stem, and the filter is positioned between the signal line and the dipole radiator printed circuit board of the first radiating element. In some embodiments, the base station antenna further includes a metamaterial structure on the first feed stem printed circuit board, the metamaterial structure overlapping the first ground line. In some embodiments, the metamaterial structure includes a ring-based metamaterial resonator.

[0024] According to an additional embodiment of the present invention, a coaxial cable is provided, the coaxial cable including a center conductor, an outer conductor, a dielectric spacer between the center conductor and the outer conductor, and an insulating cable sheath covering the outer conductor. A plurality of metamaterial structures are provided on the insulating cable sheath.

[0025] In some embodiments, the metamaterial structure includes a plurality of ring-based metamaterial resonators. The plurality of ring-based metamaterial resonators may include, for example, a plurality of complementary split-ring resonators or a plurality of split-ring resonators.

[0026] In some embodiments, the plurality of ring-based metamaterial resonators extend on the insulated cable sheath in the longitudinal direction of the coaxial cable.

[0027] In some embodiments, the coaxial cable is disposed in a base station antenna, the base station antenna including: a plurality of first radiating elements configured to operate in a first frequency band; and a plurality of second radiating elements configured to operate in a second frequency band containing higher frequencies than the first frequency band, and the metamaterial structure is configured to cancel current in the second frequency band. In some embodiments, the coaxial cable is a feed cable for one of the first radiating elements.

[0028] According to another embodiment of the present invention, a radiating element is provided, the radiating element comprising: a feed stem having a signal line, a first ground line, and a first metal post extending parallel to a first segment of the first ground line; and a radiator mounted on the feed stem. The first metal post is configured to be capacitively coupled to the first segment of the first ground line.

[0029] In some embodiments, the signal line, the first ground line, and the first metal short post are implemented on a power feed shank printed circuit board.

[0030] In some embodiments, the radiating element further includes a second metal post extending parallel to a first segment of the first grounding wire, wherein the second metal post is configured to be capacitively coupled to the first segment of the first grounding wire.

[0031] In some embodiments, the first metal post, the second metal post, and the first segment of the first ground wire are all located on the first metallization layer of the power supply shank printed circuit board. In some embodiments, the first metal post is located on a first side of the first segment of the ground wire, and the second metal post is located on a second side of the first segment of the first ground wire opposite to the first side.

[0032] In some embodiments, the radiating element further includes: a third metal post extending parallel to a second segment of the first grounding wire, wherein the third metal post is configured to be capacitively coupled to the first grounding wire; and a fourth metal post extending parallel to a second segment of the first grounding wire, wherein the fourth metal post is configured to be capacitively coupled to the first grounding wire.

[0033] In some embodiments, the radiating element further includes a first additional metal post overlapping the first metal post and a second additional metal post overlapping the second metal post, wherein the first additional metal post, the second additional metal post, and at least a first portion of the signal line are all on a second metallization layer on the power feed spool printed circuit board that is different from the first metallization layer.

[0034] In some embodiments, a first conductive via in the power supply spool printed circuit board connects the first metal short post current to the first additional metal short post, and a second conductive via in the power supply spool printed circuit board connects the second metal short post current to the second additional metal short post.

[0035] In some embodiments, a first portion of the signal line is located between the first additional metal post and the second additional metal post.

[0036] In some embodiments, the first metal post and the first segment of the first ground wire together comprise at least a portion of an inductor-capacitor circuit having a bandpass filter response. In some embodiments, the radiating element is part of a base station antenna, and the base station antenna includes a second radiating element having an operating frequency band, wherein the frequency having the highest transmission level in the bandpass filter response is within the operating frequency band.

[0037] In some embodiments, the width of a first segment of the first grounding wire is less than half the width of another segment of the first grounding wire.

[0038] In some embodiments, the first metal short post is not electrically connected to the first ground wire or the signal line.

[0039] According to an additional embodiment of the invention, a radiating element is provided, the radiating element comprising: a feed stem having a signal line and a first ground line; and a radiator mounted on the feed stem. In these radiating elements, a first segment of the first ground line is part of a resonant circuit configured to have a bandpass response within a preselected frequency range.

[0040] In some embodiments, the radiating element has a first operating frequency band and is part of a base station antenna, the base station antenna further comprising a second radiating element having a second operating frequency band, and the passband of the bandpass response is at least partially within the second operating frequency band.

[0041] In some embodiments, the feed handle further includes a first metal post configured to capacitively couple with the first ground wire. In some embodiments, the first metal post extends parallel to a first segment of the first ground wire.

[0042] In some embodiments, the signal line, the first ground line, and the first metal post are implemented on a power feed spool printed circuit board, and both the first segment of the first ground line and the first metal post are on a first metallization layer of the power feed spool printed circuit board.

[0043] In some embodiments, the radiating element further includes a second metal post extending parallel to a first segment of the first ground wire, wherein the second metal post is configured to be capacitively coupled to the first ground wire.

[0044] In some embodiments, the radiating element further includes a first additional metal post overlapping the first metal post and a second additional metal post overlapping the second metal post, wherein the first additional metal post, the second additional metal post, and at least a first portion of the signal line are all on a second metallization layer on the power feed spool printed circuit board that is different from the first metallization layer.

[0045] In some embodiments, a first portion of the signal line is located between the first additional metal post and the second additional metal post.

[0046] In some embodiments, a first conductive via in the power supply spool printed circuit board connects the first metal short post current to the first additional metal short post, and a second conductive via in the power supply spool printed circuit board connects the second metal short post current to the second additional metal short post.

[0047] According to other embodiments of the present invention, a radiating element is provided, the radiating element comprising: a feed stem printed circuit board having a signal line, a first ground line, a first metal post and a second metal post on opposite sides of a first section of the first ground line, and a first additional metal post and a second additional metal post overlapping the corresponding first metal post and second metal post; and a radiator mounted on the feed stem.

[0048] In some embodiments, the first ground wire and the first and second metal short posts are each part of a first metallization layer of the power feed spool printed circuit board, and the first and second additional metal short posts are each part of a second metallization layer of the power feed spool printed circuit board.

[0049] In some embodiments, the first metal post and the second metal post are configured to be coupled to the first grounding capacitor.

[0050] In some embodiments, the radiating element further includes: a third metal post extending parallel to a second segment of the first ground wire, wherein the third metal post is configured to be capacitively coupled to the first ground wire and is part of the first metallization layer; and a fourth metal post extending parallel to the second segment of the first ground wire, wherein the fourth metal post is configured to be capacitively coupled to the first ground wire and is part of the first metallization layer.

[0051] In some embodiments, the radiating element further includes a third additional metal post overlapping the third metal post and a fourth additional metal post overlapping the fourth metal post, wherein the third additional metal post and the fourth additional metal post are both portions of the second metallization layer of the feed stem printed circuit board.

[0052] In some embodiments, a first conductive via in the power supply spool printed circuit board connects the first metal short post current to the first additional metal short post, and a second conductive via in the power supply spool printed circuit board connects the second metal short post current to the second additional metal short post.

[0053] In some embodiments, the second metallization layer of the power supply spool printed circuit board further includes a signal line, and at least a first portion of the signal line is located between the first additional metal post and the second additional metal post.

[0054] In some embodiments, the first metal post and the first section of the first ground wire together comprise at least a portion of an inductor-capacitor circuit having a bandpass filter response.

[0055] In some embodiments, the radiating element is part of a base station antenna, which includes a second radiating element having an operating frequency band, and the frequency with the highest transmission level in the bandpass filter response is within the operating frequency band.

[0056] In some embodiments, the width of a first segment of the first grounding wire is less than half the width of another segment of the first grounding wire. Attached Figure Description

[0057] Figure 1A This is a schematic perspective view of a traditional low-frequency cross-dipole radiating element.

[0058] Figure 1B yes Figure 1A A schematic side view of a traditional low-frequency cross dipole radiating element.

[0059] Figure 2A This is a schematic perspective view of a passive / active antenna system including a passive base station antenna according to an embodiment of the present invention, wherein the passive base station antenna may be implemented using low-frequency radiating elements.

[0060] Figure 2B yes Figure 2A A schematic front view of a passive / active antenna system without a radome and frequency selection surface.

[0061] Figure 3A This is a schematic perspective view of a radiating element according to an embodiment of the present invention.

[0062] Figure 3B yes Figure 3A A schematic side view of one of the feed stem printed circuit boards included in the radiating element.

[0063] Figure 3C yes Figure 3A A schematic plan view of the first outer surface of the power supply handle printed circuit board.

[0064] Figure 3D yes Figure 3B A schematic plan view of the internal metal layer of the power supply handle printed circuit board.

[0065] Figure 3E yes Figure 3B A schematic plan view of the second outer surface of the power supply stem printed circuit board.

[0066] Figure 3F This shows all three metallization layers. Figure 3B-3E A schematic shaded plan view of the printed circuit board for the power supply handle.

[0067] Figure 3G This is a circuit diagram of the equivalent circuit of a split-ring resonator.

[0068] Figure 4A This is a schematic plan view of the first outer surface of the power supply handle printed circuit board, which can replace... Figure 3A The radiating element includes a feed stem printed circuit board.

[0069] Figure 4B yes Figure 4A A schematic plan view of the second outer surface of the power supply stem printed circuit board.

[0070] Figure 4C yes Figures 4A-4B A schematic shaded plan view of the printed circuit board for the power supply handle.

[0071] Figure 5 This is a schematic shaded side view of a radiating element with a power feed handle printed circuit board according to another embodiment of the present invention.

[0072] Figure 6 This is a schematic shaded side view of a radiating element with a feed handle printed circuit board according to an additional embodiment of the present invention.

[0073] Figures 7A-7C This is a schematic shaded plan view of a power supply handle printed circuit board according to another embodiment of the present invention.

[0074] Figure 8A and 8BThis is a schematic perspective view of a stealthy coaxial cable according to an embodiment of the present invention.

[0075] Figure 9A This is a schematic diagram illustrating how a wide microstrip trace can have a high-pass filter response.

[0076] Figure 9B It is shown that... Figure 9A A schematic diagram illustrating how a narrower microstrip trace has a high-pass filter response offset to a lower frequency compared to a wider microstrip trace.

[0077] Figure 9C This is a schematic diagram illustrating how a narrow microstrip trace with short, coplanar waveguide-shaped pillars can have a bandpass filter response.

[0078] Figure 10A This is a schematic shaded side view of the feed handle of a radiating element according to another embodiment of the present invention.

[0079] Figure 10B yes Figure 10A A schematic shaded perspective view of the concealed portion of the ground wire included on a power supply handle printed circuit board.

[0080] Figure 10C It is along Figure 10B A schematic cross-sectional view taken from line 10C-10C.

[0081] Figure 10D yes Figure 10A A schematic shaded perspective view of another hidden portion of the grounding wire included on one of the power supply handle printed circuit boards.

[0082] Figure 10E It is along Figure 10D A schematic cross-sectional view taken from line 10E-10E.

[0083] Figure 11 This is a schematic side view of the feed handle of a radiating element according to other embodiments of the present invention.

[0084] Figure 12A This is a schematic shaded side view of a mid-frequency radiating element according to an additional embodiment of the present invention.

[0085] Figure 12B This is a schematic shaded side view of a mid-frequency radiating element according to another embodiment of the present invention.

[0086] Figure 13 This is a schematic perspective view of a stealthy coaxial cable according to another embodiment of the present invention. Detailed Implementation

[0087] The aforementioned passive / active antenna systems allow cellular operators to support both traditional 2G / 3G / 4G cellular services and 5G cellular services using a single base station antenna system. However, unfortunately, in practice, the radiating elements of a passive 2G / 3G / 4G array mounted in front of a 5G beamforming array can cause "scattering" of the antenna beam generated by that 5G beamforming array. Scattering is undesirable because it can reduce the gain of the 5G antenna beam by altering its shape in both the azimuth and elevation planes. For example, scattering often negatively impacts the beamwidth, beam shape, pointing angle, gain, and front-to-back ratio of the 5G antenna beam.

[0088] Two different types of scattering can occur. First, the conductive structure of the radiating element of the lower-frequency (passive) array mounted in front of the 5G beamforming array can reflect the RF energy emitted by the radiating element of the beamforming array. Then, some of this reflected RF energy may leave the base station antenna in an undesirable direction (possibly after further reflection from other metal structures in the base station antenna, such as reflectors), or it may leave the base station antenna in a desired direction but with a phase that destructively combines the reflected RF energy with the non-reflected RF energy. The end result is that when the RF energy emitted by the beamforming array is reflected from the radiating element of the passive 2G / 3G / 4G linear array, these reflections often distort the radiation pattern generated by the beamforming array in an undesirable way.

[0089] Second-type scattering occurs when the conductive structure of the radiating element in a passive 2G / 3G / 4G linear array has an electrical length that causes the structure to resonate in the operating frequency band of a 5G beamforming array. For example, if the electrical length of the conductive structure is about half the wavelength or about the full wavelength of a frequency within the operating frequency band of a 5G beamforming array, the conductive structure of a radiating element in a passive (lower frequency band) array can resonate in the operating frequency band of a 5G (higher frequency band) beamforming array. In many cases, the operating frequency band of a beamforming array can be about four times the frequency within the operating frequency band of a passive low-frequency linear array and about twice the frequency within the operating frequency band of a passive mid-frequency linear array. Since the dipole arms of the radiating elements in, for example, low-frequency linear arrays typically have an electrical length of about ¼ of the center wavelength of the low-frequency operating frequency range, they may have a resonant length relative to the RF energy emitted by the 5G beamforming array. Therefore, the RF energy emitted by the 5G beamforming array can couple to, for example, the dipole arms of a nearby low-frequency radiating element, and the higher-frequency currents formed on these dipole arms generate additional high-frequency radiation that distorts the high-frequency antenna beam (because some RF energy is emitted from an unintended location, i.e. from the low-frequency dipole arms).

[0090] So-called "stealth" radiating elements with dipole arms are known in the art, which are designed such that they will not generate currents in response to RF radiation within a preselected frequency range (e.g., currents in the operating frequency band of high-frequency radiating elements in 5G beamforming arrays). These radiating elements can reduce or eliminate the second type of scattering described above from the dipole arms of nearby lower-frequency radiating elements to higher-frequency radiation. The present invention is partly based on the understanding that feed handles of lower-frequency radiating elements (e.g., low-frequency and / or mid-frequency radiating elements) can also cause both types of scattering. A feed handle of a cross-dipole radiating element refers to a structure that feeds RF signals to and from the dipole arm of the radiating element. In most cases, the dipole arm is mounted on the distal (front) end of the feed handle, and the base (rear) end of the feed handle is mounted on a reflector of a base station antenna or on a feed board printed circuit board mounted on the reflector.

[0091] The feed stem of the low-frequency radiating element may include multiple metallic patterns that can reflect high-frequency RF radiation emitted by a high-frequency beamforming array mounted behind the low-frequency radiating element (i.e., the feed stem of the low-frequency radiating element can cause the first type of scattering discussed above). This reflection can reduce the shape and characteristics of the antenna beam formed by the high-frequency 5G beamforming array. Additionally, the feed stem of the low-frequency radiating element typically also has a metallic structure with a length of approximately ¼ of the center wavelength of the low-frequency operating frequency range; therefore, the feed stem of the low-frequency radiating element can also cause the second type of scattering discussed above regarding the RF radiation emitted by the 5G beamforming array. Although the amount of scattering caused by the feed stem is often much lower than that caused by a non-stealthy low-frequency dipole arm, the amount of scattering may still be significant enough to distort the antenna beam formed by the 5G beamforming array.

[0092] According to embodiments of the present invention, a base station antenna is provided, comprising a low-frequency (or mid-frequency) radiating element with a stealthy feed stem, the stealthy feed stem potentially having a reducing effect on high-frequency RF radiation emitted by a high-frequency array positioned adjacent to and / or behind the low-frequency radiating element. In some embodiments, the radiating element has a feed stem comprising a metamaterial structure, such as a split-ring resonator or a complementary split-ring resonator. The metamaterial structure can be designed to cancel current in the operating frequency band(s) of nearby higher-frequency radiating elements. Thus, the metamaterial structure allows the feed stem to transmit more RF energy within one or more frequency ranges (e.g., the operating frequency range of the aforementioned high-frequency beamforming array mounted behind the low-frequency radiating element). In some embodiments, the metamaterial structure on the feed stem of the low-frequency radiating element can have a bandpass filter response, wherein they substantially transmit RF energy within the operating frequency range of the aforementioned high-frequency array. The metamaterial structure can overlap, for example, with a dual-grounded element of a microstrip feed on the feed stem to make the dual-grounded element stealthy. These metamaterial structures can, for example, allow a portion of the metal structure on the feed stalk to transmit more of the high-frequency RF radiation emitted by the aforementioned high-frequency array positioned behind the low-frequency radiating element. Since scattering tends to occur when the metal structure on the feed stalk has a length that resonates within the operating frequency band of the high-frequency array, it may be important to ensure that the feed stalk does not include a metal structure whose length is a quarter-wavelength multiple of the frequency within the operating frequency band of the high-frequency array. Therefore, it may not be necessary to completely cover the metal structure on the feed stalk with a metamaterial structure; rather, covering a portion may be sufficient so that the exposed metal structure does not resonate within the operating frequency band of the high-frequency array.

[0093] According to another embodiment of the invention, a radiating element with a feed stem having an RF feed line including a filter-based stealth circuit is provided. While resonant circuits are sometimes included on the feed stem of the radiating element of a base station antenna, these resonant circuits (e.g., capacitors or series inductor-capacitor circuits) are typically provided to impedance match the dipole arm impedance of the radiating element to the RF transmission line on the feed stem. For example, U.S. Patent No. 9,819,084 discloses the use of a capacitor-inductor-capacitor impedance matching circuit, which can be implemented on the feed stem and / or in the connection between the feed stem and the dipole arm to provide improved impedance matching. According to an embodiment of the invention, the filter-based stealth structure can be formed in a metallic structure on the feed stem. These filters can be tuned to pass RF energy in the operating frequency band of the radiating element while rejecting (blocking) RF energy in the operating frequency band of other nearby radiating elements operating in different frequency bands.

[0094] According to another embodiment of the invention, a lower-frequency radiating element is provided, the lower-frequency radiating element having a feed stem comprising one or more ground wires. At least one of the ground wires may be made relatively narrow to provide increased inductance. Short metal posts may be disposed on one or both sides of the narrow ground wires, the short metal posts introducing capacitance in parallel with the inductance of the ground wires to form an inductor-capacitor (LC) circuit with bandpass filter characteristics. The inductance value can be adjusted, for example, by adjusting the length and / or width of the ground wires, and the capacitance value can be selected by adjusting the length of the metal posts and / or the distance between the ground wires and the metal posts. By adjusting the inductance and / or capacitance values, the position of the passband of the bandpass filter can be adjusted so that the passband falls within the operating frequency band of a nearby higher-frequency radiating element. The net effect is that the addition of the short metal posts makes the ground wires on the lower-frequency radiating element stealthed from RF energy in the operating frequency band of a nearby higher-frequency radiating element.

[0095] The feed stem of a lower-frequency radiating element may include one or more feed stem printed circuit boards having a first metallization layer including a ground line (or at least a portion thereof) and a second metallization layer including a signal line (or at least a portion thereof). In some embodiments, the feed stem printed circuit board may include multiple segments in which short metal posts are disposed on one or both sides of the ground line. Each of these segments may be considered as a unit cell of a frequency selective surface. Additional short metal posts may be disposed on the opposite side of the feed stem printed circuit board, overlapping the short metal posts disposed on one or both sides of the ground line. The overlapping short metal posts and the additional short metal posts may be electrically connected to each other, for example, through plated vias in the feed stem printed circuit board.

[0096] In other embodiments of the invention, stealthy coaxial cables are provided that can have increased transmittance of RF energy in selected frequency bands. These stealthy coaxial cables may, for example, have metamaterial structures printed on the outer protective sheath of the cable. These metamaterial structures can be designed to allow the coaxial cable to transmit more RF energy in one or more frequency ranges, thereby reducing the degree to which the coaxial cable scatters RF energy in these frequency ranges. The metamaterial structure may include, for example, a split-ring resonator or a complementary split-ring resonator. In other embodiments, a short metal sleeve section may be provided on the coaxial cable, which is designed to have a bandpass filter response that makes the coaxial cable stealthy within a predetermined frequency range.

[0097] Before discussing the radiating elements according to embodiments of the present invention, it is helpful to discuss the design and operation of representative conventional low-frequency radiating elements of base station antennas, as well as base station antennas in which radiating elements and coaxial cables according to embodiments of the present invention can be used.

[0098] Figure 1A This is a perspective view of a traditional low-frequency cross-dipole radiating element 1. Figure 1B This is a shaded side view of the cross-dipole radiating element 1, showing the metallization pattern on the printed circuit board 20-1 of the first feed stem of the radiating element 1. Figure 1B In the diagram, the solid line represents the metallization pattern on the first side of the power supply handle printed circuit board 20-1, and the dashed line represents the metallization pattern on the second (opposite) side of the power supply handle printed circuit board 20-1. Figure 1B In this context, since the main surface of the power supply handle printed circuit board 20-2 is perpendicular to the viewing angle, only the side surface of the second power supply handle printed circuit board 20-2 is visible. It should be noted that, herein, the same element may be referred to individually by its entirety (e.g., power supply handle printed circuit board 20-2) and may be referred to collectively by the first part of its reference numerals (e.g., power supply handle printed circuit board 20).

[0099] like Figure 1A As shown, a conventional cross-dipole radiating element 1 includes a feed handle 10 and a pair of dipole radiators 70-1, 70-2. The feed handle 10 includes a first feed handle printed circuit board and a second feed handle printed circuit board 20-1, 20-2. Each feed handle printed circuit board 20-1, 20-2 includes a corresponding RF feed line 16-1, 16-2. The RF feed lines 16-1, 16-2 transmit RF signals between a first RF transmission line and a second RF transmission line (not shown) connected to the radiating element 1 to transmit RF signals to and from the radiating element 1. Each such RF transmission line may include, for example, a coaxial cable or a microstrip transmission line on the feed board printed circuit board.

[0100] refer to Figure 1A and 1B Both, each power supply spool printed circuit board 20 has a base 22 and a distal end 24 positioned in front of the base 22. The first power supply spool printed circuit board 20-1 includes a slit 26 extending forward from its base 22, and the second power supply spool printed circuit board 20-2 includes a slit 26 extending rearward from its distal end 24. The power supply spool printed circuit boards 20-1 and 20-2 are arranged perpendicular to each other, their slits 26 engaging such that, when viewed from the front, the two mating power supply spool printed circuit boards 20-1, 20-2 have a cross shape.

[0101] The rear portion of each feed handle printed circuit board 20 may include a protrusion inserted through a slot (not shown) in the feed handle printed circuit board. Metallization pads on the protrusions may be soldered to metallization pads on the feed handle printed circuit board to mechanically mount the radiating element 1 onto the feed handle printed circuit board and electrically connect the RF feed lines 16-1, 16-2 on the feed handle 10 to RF transmission lines on the feed handle printed circuit board.

[0102] Dipole radiators 70-1 and 70-2 are positioned at the distal end 24 of the feed handle printed circuit board 20 and can (and typically) be physically mounted on the feed handle printed circuit board 20. The first dipole radiator 70-1 extends along a first axis, and the second dipole radiator 70-2 extends along a second axis substantially perpendicular to the first axis. The first dipole radiator 70-1 includes a first dipole arm and second dipole arms 80-1 and 80-2, and the second dipole radiator 70-2 includes a third dipole arm and fourth dipole arms 80-3 and 80-4. Dipole radiators 70-1 and 70-2 can be formed in a dipole radiator printed circuit board 82. The dipole arm 80 is a stealthy dipole arm formed as a series of widened metal segments 84 interconnected by narrow metal traces 86 (see [link to original text]). Figure 1A As shown, the narrow metal trace 86 can be a "zigzag" trace with a U-shape (or other zigzag shape), allowing the trace to have a relatively long length while accommodating the small space between adjacent widened metal segments 84. The average width of each widened metal segment 84 can be at least three times, at least four times, or at least five times the average width of each narrow metal trace 86. Dipole radiators 70-1, 70-2 are shown as having an elongated "number 8" shape, wherein each dipole arm 80 is formed as a ring. Various dipole arms are known in the art, including dipole arms having many different shapes or formed in different ways (e.g., using metal plates). It should be understood that a radiating element having the feed handle design disclosed herein according to embodiments of the invention can have any suitable dipole arm design.

[0103] The dipole arms 80-1 and 80-2 of the first dipole radiator 70-1 are center-fed by the first RF feed line 16-1 on the first feed handle printed circuit board 20-1 and radiate together at the first polarization. In the depicted embodiment, the first dipole radiator 70-1 is designed to transmit and receive signals with a polarization of +45°. 0 Linearly polarized signals. The dipole arms 80-3 and 80-4 of the second dipole radiator 70-2 are center-fed by the second RF feed line 16-2 on the second feed handle printed circuit board 20-2, and radiate together at the second polarization orthogonal to the first polarization. The second dipole radiator 70-2 is designed to transmit and receive signals with a tilt of -45°. 0 Linearly polarized signals.

[0104] like Figure 1B As shown, a dual-line transmission line structure is formed on the second side of the power supply handle printed circuit board 20-1. The dual-line transmission line structure includes a first ground line and second ground lines 30-1, 30-2, which are implemented as first and second metallized regions extending from the base 22 of the first power supply handle printed circuit board 20-1 to its distal end 24. Each ground line 30-1, 30-2 is coupled to a ground conductor (not shown) of the first RF transmission line that powers the radiating element 1. The connection between the first and second ground lines 30-1, 30-2 and the ground conductor of the first RF transmission line can be located at the base 22 of the first power supply handle printed circuit board 20-1. The first and second ground lines 30-1, 30-2 may each have an electrical length of approximately ¼ of the center wavelength of the radiating element 1.

[0105] Signal line 40 is formed on the first side of the power supply spool printed circuit board 20-1. Signal line 40 is coupled to the signal conductor of the RF transmission line that powers the first power supply spool printed circuit board 20-1. Signal line 40 extends forward from the base 22 of the first power supply spool printed circuit board 20-1 and travels approximately two-thirds of the distance toward its distal end 24. Then, signal line 40 passes through the first 90°... 0 The direction is changed to extend laterally across the first side of the power supply spool printed circuit board 20-1. Finally, signal line 40 passes through the second 90. 0 It is turned to extend rearward toward the base 22 of the first power supply handle printed circuit board 20-1.

[0106] Signal line 40 includes a forward extending segment 42-1, a lateral extending segment 42-2, and a rearward extending segment 42-3. The forward extending segment 42-1 overlaps with the first ground line 30-1. In this document, two elements are considered "overlapping" if an axis perpendicular to the main surface of the printed circuit board intersects two elements on the printed circuit board (or equivalent structure). The lateral extending segment 42-2 extends from the end of the forward extending segment 42-1 to cross the gap 36 (i.e., the unmetallized area) between the first and second ground lines 30-1, 30-2. The lateral extending segment 42-2 partially overlaps with both the first and second ground lines 30-1 and 30-2. The rearward extending segment 42-3 extends rearward from the end of the lateral extending segment 42-2 at a right angle toward the base 22 of the first feed stem printed circuit board 20-1. The rearward extending segment 42-3 overlaps with the second ground line 30-2.

[0107] Figure 2A-2B A conventional passive / active antenna system 100 is shown, comprising both a passive base station antenna 110 and an active antenna module 150. Specifically, Figure 2AThis is a schematic rear perspective view of a passive / active antenna system 100, and Figure 2B It eliminates the need for antenna covers on both the passive base station antenna 110 and the active antenna module. Figure 2A A schematic perspective view of a passive / active antenna system 100. Figure 2A and 2B In the diagram, the axes indicate the longitudinal (L), lateral (T), and forward (F) directions of the base station antenna system 100. In the following description, the antenna 100 and its included radiating elements will be described using the following terms, which assume that the antenna 100 is mounted on a tower for normal use, wherein the longitudinal axis of the antenna 100 extends along a vertical axis, and the front surface of the antenna 100 is mounted opposite the tower pointing towards the coverage area of ​​the antenna 100.

[0108] refer to Figure 2A The passive / active antenna system 100 can be mounted on, for example, an antenna tower 102 using mounting hardware 104. The active antenna module 150 can be directly mounted on the rear surface of the passive base station antenna 110, or it can be held in place behind the passive base station antenna 110 by the mounting hardware 104. The front surface of the passive / active antenna system 100 can be opposite the antenna tower 102 facing the coverage area of ​​the passive / active antenna system 100. The passive base station antenna 110 includes a tubular radome 112 that surrounds and protects the antenna assembly mounted inside the radome 112. A top cover 114 covers a top opening in the radome 112, and a bottom cover 116 covers a bottom opening in the radome 112. A plurality of RF ports 118 extend through the bottom cover 116 and are used to connect the passive base station antenna 110 to one or more external radio devices (not shown). The active antenna module 150 can be removably mounted behind the passive base station antenna 110, so that the active antenna module 150 can be replaced later with a different active antenna module.

[0109] refer to Figure 2BThe passive base station antenna 110 includes a reflector assembly 120. The reflector assembly 120 may be referred to herein as a "passive reflector assembly" as it is part of the passive base station antenna 110. The passive reflector assembly 120 includes a main reflector 122 and spaced-apart first and second reflector strips 124-1, 124-2, the first and second reflector strips extending longitudinally from corresponding first and second opposite sides of the main reflector 122. The passive reflector assembly 120 may also include a third reflector strip 124-3 extending in a lateral direction between the top ends of the first and second reflector strips 124-1, 124-2. An opening 126 is defined between the first reflector strip and the second reflector strips 124-1, 124-2. For example, opening 126 may be defined by the top portion of main reflector 122, first reflector strips and second reflector strips 124-1, 124-2, and third reflector strip 124-3. At least the main reflector 122 may include a metallic surface (e.g., an aluminum sheet) that acts as a reflector and ground plane for the radiating elements of antenna 100. Various mechanical and electronic components (not shown) of the antenna may be mounted behind the passive reflector assembly 120; these components are, for example, phase shifters, remote electronic tilting units, mechanical linkages, controllers, duplexers, etc.

[0110] The passive base station antenna 110 also includes a plurality of passive linear arrays of radiating elements extending forward from the passive reflector assembly 120. The linear arrays can support, for example, 2G, 3G, and / or 4G cellular services. Figure 2A-2B In the exemplary passive base station antenna 110 shown, the linear array includes a first low-frequency band linear array and second low-frequency band linear arrays 130-1 and 130-2 configured to operate in all or part of the 617-960MHz frequency band. Each low-frequency band linear array 130 includes a vertically extending column of low-frequency band radiating elements 132. The passive base station antenna 110 also includes a first intermediate-frequency band linear array 140-1 to a fourth intermediate-frequency band linear array 140-4 configured to operate in all or part of the 1427-2690MHz frequency band. Each intermediate-frequency band linear array 140 includes a vertically extending column of intermediate-frequency band radiating elements 142. Each of the low-frequency linear array and the mid-frequency linear array 130, 140 can generate a static antenna beam (e.g., each configured to cover a sector of a base station) that provides coverage to a predefined coverage area, wherein only the coverage area changes when the electronic downtilt angle of the generated antenna beam is adjusted (e.g., to change the size of the sector served by the passive base station antenna 110).

[0111] Each of the low-frequency and mid-frequency radiating elements 132 and 142 can be implemented as a dual-polarized radiating element, comprising a first radiator and a second radiator that transmits and receives RF energy in orthogonal polarization. When using such a dual-polarized radiating element, each of the low-frequency and mid-frequency linear arrays 130 and 140 can be connected to a pair of RF ports 118. The first RF port 118 connects between a first port of the radio device (e.g., a remote radio head mounted on antenna tower 102 near the passive base station antenna 110) and a first polarized radiator of the radiating element in one of the linear arrays, and the second RF port 118 connects between a second port of the radio device and a second polarized radiator of the radiating element in the linear array. An RF signal to be transmitted by a selected linear array in linear arrays 130 and 140 is transmitted from one of the multiple radio devices to one of the RF ports 118, and from the RF port 118 to a power divider (or, alternatively, including a phase shifter assembly of the power divider), which divides the RF signal into multiple sub-components, which are fed to a corresponding first or second radiator of a radiating element in the linear array, wherein the sub-components of the RF signal are radiated into free space.

[0112] Low-frequency and / or mid-frequency radiating elements 132 and 142 can be mounted on a feed board printed circuit board that couples RF signals to and from each of the radiating elements 132 and 142. Figure 2B In the diagram, the mid-frequency radiating elements 142 are shown mounted in pairs on multiple mid-frequency feed board printed circuit boards 148 (the low-frequency radiating elements are also mounted on the feed board printed circuit boards, but they are not visible in the figures). Cables can be used to connect each feed board printed circuit board 148 to other components of the antenna, such as duplexers, phase shifters, etc.

[0113] Most of the low-frequency and mid-frequency radiating elements 132, 142 are mounted to extend forward from the main reflector 122. However, the low-frequency linear arrays 130-1, 130-2 essentially extend the entire length of the passive / active antenna system 100 and thus extend beyond the main reflector 122. The first and second reflector strips 124-1, 124-2 can provide mounting locations for the low-frequency radiating elements 132 positioned above the main reflector 122. The first and second reflector strips 124-1, 124-2 can be integrated with the main reflector 122 such that the first and second reflector strips 124-1, 124-2 and the main reflector 122 will be maintained at a common ground voltage, which can improve the performance of the low-frequency linear arrays 130-1, 130-2.

[0114] Each low-frequency radiating element 132 may include a tilt of -45 degrees. 0 / +45 0 A crossed dipole radiating element, the crossed dipole radiating element comprising a tilt of -45 degrees 0 Polarized dipole radiator 134-1 and tilt +45 0 Polarized dipole radiators 134-2. Dipole radiators 134-1, 134-2 may be mounted on a feed handle (not shown). In some cases, the three uppermost low-frequency radiating elements 132 may be mounted on a frequency selective surface (not shown) covering the opening 126. This frequency selective surface is described in more detail below. In other cases, the low-frequency radiating elements 132 may include a tilted feed handle that allows these radiating elements to be mounted on the first reflector strip and the second reflector strips 124-1, 124-2, with the dipole radiators 134 of these radiating elements 132 in front of the opening 126 (and any FSS covering the opening 126). Each low-frequency radiating element 132 has a dipole radiator 134 that is designed to substantially transmit the RF energy emitted by the mid-frequency radiating element 142.

[0115] The active antenna module 150 includes a multi-row beamforming array 160 of high-frequency radiating elements 162 and a beamforming radio (not visible in the figure). The multi-row beamforming array 160 may be mounted in the front portion of the active antenna module 150, and the beamforming radio may be mounted behind the multi-row beamforming array 160. The beamforming array 160 may, for example, include multiple vertically extending rows of high-frequency radiating elements 162 configured to operate in all or part of the 3.1–4.2 GHz frequency band (e.g., in the 3.1–3.6 GHz band). The high-frequency radiating elements 162 are mounted to extend forward from the reflector 154 (referred to herein as the “active reflector”) of the active antenna module 150. The beamforming radio is capable of electronically adjusting the amplitude and / or phase of sub-components of the RF signals output to the different radiating elements 162 of the multi-row beamforming array 160. For example, each port of the beamforming radio can be coupled to a column of high-frequency radiating elements 162 of the beamforming array 160, and the amplitude and phase of the sub-components of the RF signal fed to each column can be adjusted so that the generated antenna beam narrows in the azimuth plane and points in the desired direction in the azimuth plane.

[0116] The beamforming array 160 of the active antenna module 150 is mounted behind the opening 126 in the passive reflector assembly 120. The beamforming array 160 is... Figure 2B As can be seen, because Figure 2BThe frequency selective surface and the radome of the passive base station antenna 110 are omitted, as is the radome of the active antenna module 150. The opening 126 in the passive reflector assembly 120 (and any frequency selective surface extending across the opening 126) allows the antenna beam generated by the beamforming array 160 to pass through the passive base station antenna 110 to provide service to the coverage area of ​​the passive / active antenna system 100.

[0117] As discussed above, a frequency selective surface (not shown) may cover opening 126. The frequency selective surface may be configured to allow RF energy emitted by the high-frequency radiating element 162 in the beamforming array 160 to pass through it, while simultaneously reflecting lower-frequency RF energy (and specifically, low-frequency RF signals emitted by the low-frequency radiating element 132). The frequency selective surface may be coplanar with opening 126, either in front of or behind opening 126. The frequency selective surface may have a grid pattern, such as a grid of metal pads and / or other metal structures. The grid pattern may be arranged in any suitable manner and may be symmetrical or asymmetrical across the width and / or length of the frequency selective surface. The grid pattern may include sub-wavelength periodic microstructures. The metal pads / structures may be arranged in one or more layers. The frequency selective surface may be formed on a substrate (e.g., a printed circuit board or stamped metal sheet in an exemplary embodiment). In some embodiments, the frequency selective surface may include portions of the passive reflector assembly 120 stamped therein to form a metal grid structure. In such cases, “opening” 126 comprises a number of small openings that act as large openings relative to the RF energy in the operating frequency band of beamforming array 160.

[0118] Figure 2A-2B One challenge with the passive / active base station antenna system 100 is that some of the low-frequency radiating elements 132 are mounted directly in front of the high-frequency beamforming array 160. Therefore, the metal elements of the low-frequency radiating elements 132 can partially block / reflect the RF radiation emitted by the high-frequency beamforming array 160, and / or the high-frequency RF radiation can induce a current in the metal elements of the low-frequency radiating elements 132, which then re-radiates the high-frequency radiation in a manner that distorts the shape of the antenna beam generated by the high-frequency beamforming array 160.

[0119] As discussed above, according to embodiments of the present invention, a cross-dipole radiating element is provided having a feed handle that is at least partially transparent to RF energy in the operating frequency band of one or more nearby higher-frequency radiating elements. Specifically, the radiating element according to embodiments of the present invention may include metamaterial structures and / or filters that are at least partially transparent in the operating frequency band of nearby higher-frequency radiating elements. Therefore, the feed handle of the radiating element according to embodiments of the present invention can cause less scattering of RF energy emitted by nearby higher-frequency radiating elements, which can improve the peak directivity and shape of the antenna beam generated by an array of nearby higher-frequency radiating elements.

[0120] The following discussion of cross-dipole radiating elements according to embodiments of the invention will focus on low-frequency radiating elements having a feed stem that is partially transparent to RF radiation emitted relative to, for example, nearby high-frequency radiating elements. However, it should be understood that the techniques disclosed herein can be used, for example, to provide mid-frequency radiating elements that are partially transparent to RF radiation emitted relative to nearby high-frequency radiating elements, or for any other suitable application. Therefore, although radiating elements according to embodiments of the invention are described below as low-frequency radiating elements, it should be understood that they can alternatively be reduced in size to function as, for example, mid-frequency radiating elements.

[0121] Figure 3A This is a schematic perspective view of a radiating element 200 according to an embodiment of the present invention. Figure 3B yes Figure 3A A schematic side view of one of the feed stem printed circuit boards included in the radiating element. Figure 3C yes Figure 3A A plan view of the first outer surface of the power supply handle printed circuit board. Figure 3D yes Figure 3B A schematic plan view of the internal metal layer of the power supply handle printed circuit board. Figure 3E yes Figure 3B A schematic plan view of the second outer surface of the power supply stem printed circuit board. Figure 3F This shows all three metallization layers. Figure 3B-3E A schematic shaded plan view of the printed circuit board for the power supply handle.

[0122] refer to Figure 3AThe radiating element 200 includes a feed handle 210, a first dipole radiator 270-1, and a second dipole radiator 270-2. The dipole radiators 270-1 and 270-2 are mounted adjacent to the distal end of the feed handle 210 (and are typically mounted on the distal end of the feed handle). The first dipole radiator 270-1 includes a first dipole arm and second dipole arms 280-1 and 280-2, and the second dipole radiator 270-2 includes a third dipole arm and fourth dipole arms 280-3 and 280-4. The dipole radiators 270 and dipole arms 280 can be referenced above. Figure 1A-1B The dipole radiator 70 and dipole arm 80 are described as being the same, so further description of them will be omitted here.

[0123] The feed handle 210 includes a first feed handle printed circuit board and second feed handle printed circuit boards 220-1 and 220-2. Each feed handle printed circuit board 220 has a base and a distal (front) end positioned in front of the base. A dipole radiator 270 is mounted at the distal end of the feed handle printed circuit board 220. The first feed handle printed circuit board 220-1 includes a slit extending rearward from its distal end (see...). Figure 3B The second power supply spool printed circuit board 220-2 includes a slit extending forward from its base. The power supply spool printed circuit boards 220-1 and 220-2 are arranged perpendicular to each other, wherein the slits in the two power supply spool printed circuit boards 220 receive each other, such that when viewed from the front, the two mating printed circuit boards 220-1, 220-2 have a cross shape.

[0124] like Figure 3B As shown, the first power supply stalk printed circuit board 220-1 can be implemented using a multilayer printed circuit board, which includes a first dielectric substrate and a second dielectric substrate 222-1, 222-2 stacked together. A first metallization pattern and a third metallization pattern 224-1, 224-3 are disposed on the respective outer main surfaces of the first dielectric substrate and the second dielectric substrate 222-1, 222-2, and a second metallization pattern 224-2 is disposed between the first dielectric substrate and the second dielectric substrate 222-1, 222-2.

[0125] Figure 3C-3E This is a plan view showing each of the corresponding first metallization patterns 224-1 to third metallization patterns 224-3 of the first power supply printed circuit board 220-1 (assuming that the second metallization pattern 224-2 is formed on the second dielectric substrate 222-2). Figure 3F This is a shaded plan view of the first power supply shank printed circuit board 220-1, which shows the relative positions of the metal structures of all three first metallization patterns 224-1 to third metallization patterns 224-3.

[0126] like Figure 3C As shown, a first metallization pattern 224-1 is formed on the outer surface of a first dielectric substrate 222-1. The first metallization pattern 224-1 includes a two-wire transmission line structure comprising a first metal ground wire and second metal ground wires 246-1, 246-2 extending distally from the base of a first feed handle printed circuit board 220-1. Each ground wire 246-1, 246-2 is coupled at or near the base of the first feed handle printed circuit board 220-1 to a ground conductor of a first RF transmission line that powers a radiating element 200 (not shown). The first ground wire and the second ground wire 246-1, 246-2 may each have an electrical length of approximately ¼ of the center wavelength of the radiating element 200.

[0127] like Figure 3D As shown, a second metallization pattern 224-2 is formed on the inner surface of either the first dielectric substrate 222-1 or the second dielectric substrate 222-2 (or both). The second metallization pattern 224-2 includes a signal line 240 coupled to a signal conductor of an RF transmission line that powers the first feed handle printed circuit board 220-1. The signal line 240 extends forward from the base of the first feed handle printed circuit board 220-1 and travels approximately two-thirds of the distance toward its distal end. The signal line 240 then passes through a first 90°... 0 The direction changes so that it extends laterally across the first side of the power supply spool printed circuit board 220-1. Finally, the signal line 240 passes through the second 90... 0 It is turned to extend rearward toward the base of the first power supply handle printed circuit board 220-1.

[0128] Signal line 240 includes a forward extending segment 242-1, a lateral extending segment 242-2, and a rearward extending segment 242-3. The forward extending segment 242-1 overlaps with the first grounding wire 246-1 (see...). Figure 3F In this document, if an axis perpendicular to the main surface of the printed circuit board intersects two components on the printed circuit board (or equivalent structure), then the two components are considered to "overlap". Lateral extension segment 242-2 extends from the end of forward extension segment 242-1 to cross the gap 236 (i.e., the unmetallized area) disposed between the first ground wire and the second ground wires 246-1, 246-2 (see...). Figure 3C The lateral extension segment 242-2 partially overlaps with both the first grounding wire 246-1 and the second grounding wire 246-2. The rearward extension segment 242-3 extends rearward from the end of the lateral extension segment 242-2 toward the base of the first power supply handle printed circuit board 220-1 at a right angle. The rearward extension segment 242-3 overlaps with the second grounding wire 246-2.

[0129] Signal trace 240, together with the first ground wire and the second ground wires 246-1 and 246-2, form RF feed line 216-1 (see...). Figure 3F The RF feed line transmits RF signals between the RF transmission line (not shown) of the feed network for the radiating element 200 and the cross-dipole radiator 270-1. The RF transmission line of the feed network may include, for example, a coaxial cable or a microstrip transmission line on the feed board printed circuit board. The RF feed line 216-1 transmits RF signals between the cross-dipole radiator 270-1 and other components of the base station antenna including the radiating element 200.

[0130] like Figure 3E As shown, a third metallization pattern 224-3 is formed on the outer surface of the second dielectric substrate 222-2. The third metallization layer 224-3 includes a pair of metamaterial structures 250. Each metamaterial structure 250 may overlap with a corresponding one of ground lines 246-1, 246-2. In the depicted embodiment, each metamaterial structure 250 includes a plurality of complementary split-ring resonators 252 arranged along an axis defined by the corresponding ground lines 246-1, 246-2. The complementary split-ring resonator is a ring-based metamaterial resonator. Another known metamaterial ring resonator is the split-ring resonator. A split-ring resonator consists of a pair of concentric metal rings (also called loops) typically formed by etching a metal layer on a dielectric substrate (e.g., using printed circuit board manufacturing techniques). Slits may be formed on opposite sides of the rings. The rings may be square, circular, elliptical, rectangular, or any other suitable shape. A small gap is provided between the two rings. The magnetic flux incident on a split-ring resonator induces a rotating current in the rings, and in response to this current, the rings generate their own flux to enhance or counteract the incident electromagnetic field (depending on the resonant characteristics of the split-ring resonator). The small gaps between the rings produce a large capacitance value that lowers the resonant frequency, allowing the split-ring resonator to function in response to RF energy as if it were electrically smaller (compared to its physical size). The equivalent circuit of a single split-ring resonator is as follows: Figure 3G As shown in the diagram, L represents inductive coupling and C represents capacitive coupling. The resonant frequency of the split-ring resonator is:

[0131]

[0132] A complementary split-ring resonator is a complementary structure to a split-ring resonator. Therefore, a complementary split-ring resonator can be formed by providing a metal layer and then removing the metal to create a non-metallized region having the shape of a split-ring resonator. In other words, a complementary split-ring resonator is the negative image of the aforementioned split-ring resonator. Embodiments of the invention are shown herein as implemented as complementary split-ring resonators; however, it should be understood that split-ring resonators or other metamaterial structures may be used in other embodiments.

[0133] As described above, each complementary split-ring resonator 252 will have a resonant frequency. Therefore, each complementary split-ring resonator 252 can function as a bandpass or bandstop filter that does not transmit RF energy in a frequency range centered on the resonant frequency. Within the stopband, the current induced in the complementary split-ring resonator in response to the RF energy emitted by nearby radiating elements is canceled out within the ring structure. Thus, by designing the complementary split-ring resonator 252 to have a resonant frequency within the operating frequency band of nearby higher-frequency radiating elements, the complementary split-ring resonator 252 can "hide" the RF radiation emitted by nearby higher-frequency radiating elements from the dual ground wires 246-2, 246-2, without forming a metallic structure on which high-frequency currents will form. As a result, the complementary split-ring resonator 252 allows the feed stem printed circuit board 220-1 to transmit more RF signals in the operating frequency band of nearby higher-frequency radiating elements.

[0134] In some embodiments, to broaden the frequency range of RF signals that the feed stem printed circuit board 220-1 will transmit more of, the resonant frequencies of the complementary split-ring resonators 252 can be designed to have different resonant frequencies spaced apart from those of nearby higher-frequency radiating elements. For example, if the operating frequency band of nearby higher-frequency radiating elements is 3.1-3.7 GHz, the resonant frequencies of the complementary split-ring resonators 252 can be selected to be, for example, 3.15 GHz, 3.3 GHz, 3.45 GHz, and 3.6 GHz. The resonant frequency of each complementary split-ring resonator 252 can be adjusted by changing the inductance and / or capacitance of each segment. For example, the resonant frequency can be changed by varying the length of each segment while keeping all other parameters constant.

[0135] Figure 3F This is a schematic shaded plan view of the first power supply stem printed circuit board 220-1, which shows how the various metal structures of the first metallization layer 224-1 to the third metallization layer 224-3 overlap.

[0136] The second power supply handle printed circuit board 220-2 may have a design substantially the same as the first power supply handle printed circuit board 220-1, except that the slit in the second power supply handle printed circuit board 220-2 extends forward from its base rather than backward from its distal end, as is the case with the slit in the first power supply handle printed circuit board 220-1, and the signal line 240 on the second power supply handle printed circuit board 220-2 extends further forward before bending to form a U-shape, allowing the signal line 240 to extend through the slit. Therefore, further description of the second power supply handle printed circuit board 220-2 will be omitted here.

[0137] By adding metamaterial structure 250 to the first feed stem printed circuit board and the second feed stem printed circuit boards 220-1, 220-2, the negative impact that the feed stem 210 of the low-frequency radiating element 200 may have on the antenna beam generated by the high-frequency beamforming array 160 can be reduced. The first ground line and the second ground lines 30-1, 30-2, which are part of the feed stem 10 of the conventional low-frequency radiating element 1, each include a large metallized area. Therefore, when Figure 2A-2B When the passive / active antenna system 100 includes a linear array of low-frequency radiating elements 1, the ground wire 20 can reflect RF radiation emitted by the high-frequency beamforming array 160 (i.e., can cause first-type scattering), especially when the high-frequency beamforming array 160 is electronically scanned in the azimuth plane. Furthermore, the first and second ground wires 30-1, 30-2 can each have a length of approximately ¼ of the center wavelength of the radiating element 1, and thus can have a length of approximately one wavelength for frequencies within the operating frequency range of the high-frequency beamforming array 160. Therefore, a high-frequency current can be formed on the ground wire 20 in response to the RF radiation emitted by the high-frequency beamforming array 160, and the ground wire 20 can then emit high-frequency radiation in response to these currents, meaning that the conventional feed handle 10 can also cause the second type of scattering discussed above. Because the low-frequency radiating element 200 according to an embodiment of the invention has a feed stem printed circuit board 220 with dual ground lines 246 that utilize metamaterial structures 250 for RF energy stealth in the high-frequency range, the influence of the feed stem 210 on the high-frequency antenna beam can be reduced. For example, using a stealthy feed stem can increase the gain of the high-frequency beamforming array by 0.1 dB to 0.2 dB.

[0138] Figures 4A-4C This is a schematic diagram of the power supply handle printed circuit board 320-1, which can replace... Figure 3B-3E The power supply handle printed circuit board 220-1 is used. Specifically, Figure 4A This is a schematic plan view of the first main surface of the power supply handle printed circuit board 320-1. Figure 4B This is a schematic plan view of the second main surface of the power supply stem printed circuit board 320-1, and Figure 4C This is a schematic shaded plan view of the power supply handle printed circuit board 320-1.

[0139] like Figures 4A-4C As shown, the power supply stalk printed circuit board 320-1 is implemented using a printed circuit board including a single dielectric substrate 322, the single dielectric substrate having a first metallization pattern and second metallization patterns 324-1, 324-2 disposed on its respective main surfaces. The first metallization pattern 324-1 can be coupled with... Figure 3BThe first metallization pattern 224-1 shown is substantially the same, therefore further description thereof will be omitted. Reference Figure 4B The second metallization pattern 324-2 includes both signal lines 240 and metamaterial structures 250, which are formed on... Figure 3B-3E On the corresponding second and third metallization patterns 224-2, 224-3 of the first feed stem printed circuit board 220-1. The metamaterial structure 250 (which is again shown as an example of a complementary split-ring resonator 252) is spaced slightly further apart in the second metallization pattern 324-2, such that the first and third segments 242-2, 242-3 of the signal trace 240 can overlap with the first and second ground lines 246-1, 246-2, respectively. The stealth performance of the first feed stem printed circuit board 320-1 may not be as good as that of the first feed stem printed circuit board 220-1 because the metamaterial structure 250 does not completely overlap with the corresponding ground lines 246-1, 246-2, but the cost may be reduced due to the use of a single-layer printed circuit board.

[0140] Figure 5 This is a schematic shaded side view of a low-frequency radiating element 400 according to another embodiment of the present invention. The low-frequency radiating element 400 includes a feed handle 410 and a first dipole radiator and second dipole radiators 470-1 and 470-2. The dipole radiators 470-1 and 470-2 can be referenced above. Figure 1A-1B The dipole radiator 70 described is the same, so further description of it will be omitted here.

[0141] The power supply handle 410 includes a first power supply handle printed circuit board and second power supply handle printed circuit boards 420-1 and 420-2. The power supply handle printed circuit boards 420-1 and 420-2 can be connected to... Figure 1A-1B The feed stem printed circuit boards 20-1 and 20-2 of the conventional radiating element 1 are the same, except that the front side of each feed stem printed circuit board 420-1 and 420-2 includes a metamaterial structure 450. For example, as Figure 5 As shown, the first to third complementary split-ring resonators 452 are formed on the front side of the feed stem printed circuit board 420-1. Each complementary split-ring resonator 452 overlaps with a corresponding portion of one of a pair of dual ground wires 446-1, 446-2. The complementary split-ring resonators 452 can be designed to cancel out high-frequency currents that would otherwise form on them, and thus can be used to allow the feed stem printed circuit board 420-1 to transmit more RF energy in the high-frequency range.

[0142] The complementary split-ring resonator 452 can be used to allow the overlapping portion of the dual ground wires 446-1, 446-2 to transmit high-frequency RF energy. This can advantageously "decompose" a metal structure (e.g., dual ground wires 446-1, 446-2) with a length that can resonate in the high-frequency range into multiple smaller metal structures that may not resonate in the high-frequency range. This can further help to allow more RF energy in the high-frequency energy range to be transmitted through the feed handle printed circuit board 420. Therefore, the influence of the feed handle printed circuit board 420-1 on the antenna beam generated by the high-frequency array mounted behind the radiating element 400 can be significantly reduced, thereby improving the performance of the high-frequency array. The feed handle printed circuit board 420-2 can have a substantially the same design as the feed handle printed circuit board 420-1, except that the position of the slit can be reversed, and the shape of the signal line 440 on the second feed handle printed circuit board 420-2 is adjusted accordingly in the same manner as discussed above with respect to the second feed handle printed circuit board 220-2.

[0143] Figure 6 This is a schematic shaded side view of a low-frequency radiating element 500 with a stealthy feed handle printed circuit board according to an additional embodiment of the present invention. The low-frequency radiating element 500 includes a feed handle 510 and a first dipole radiator and second dipole radiators 570-1 and 570-2. The dipole radiators 570-1 and 570-2 can be referenced above. Figure 1A-1B The dipole radiator 70 described is the same, so further description of it will be omitted here.

[0144] The power supply handle 510 includes a first power supply handle printed circuit board and second power supply handle printed circuit boards 520-1 and 520-2. The power supply handle printed circuit boards 520-1 and 520-2 can be connected to... Figure 1A-1B The conventional radiating element 1 has the same feed stem printed circuit boards 20-1 and 20-2, except that the front (far) end of each ground wire 546-1 and 546-2 is modified to include a series inductor-capacitor (LC) circuit 560-1 and 560-2. Specifically, the front portion of each ground wire 546-1 and 546-2 (note that ground wires 546-1 and 546-2 are implemented on the rear side of the feed stem printed circuit board 520-1) includes a narrowed zigzag trace 562 forming the corresponding inductor. The front portion of each ground wire 546-1 and 546-2 also includes a board 564 connected in series to the corresponding zigzag trace 562. A corresponding board 566 is also disposed on the front side of the feed stem printed circuit board 520-1, overlapping with board 564, such that each pair of boards 564 and 566 forms the corresponding capacitor. In other words, the zigzag trace 562 and the boards 564 and 566 form a pair of series LC circuits at the front portion of each grounding wire 546-1 and 546-2.

[0145] The LC circuit formed in the front portion of ground lines 546-1, 546-2 can be tuned to transmit RF energy in the low-frequency operating band while rejecting (blocking) RF energy in the operating band of other nearby radiating elements operating in different bands (e.g., the operating band of the nearby beamforming array 160). Therefore, the LC circuit can act as a filter blocking high-frequency currents. It should be understood that the aforementioned filter can be implemented at other locations along either or both of the dual ground lines 546-1, 546-2, and / or more than one such filter can be arranged along either or both of the dual ground lines 546-1, 546-2. The LC circuit can also be designed to provide appropriate impedance matching between the RF transmission lines in the feed stem printed circuit boards 520-1, 520-2 and the dipole radiators 570-1, 570-2.

[0146] like Figure 6 As also shown, one or more metamaterial structures 550 may also be disposed on the feed stem printed circuit board 520-1. For example, one or more complementary split-ring resonators 552 may be formed on the front side of the feed stem printed circuit board 520-1, the one or more complementary split-ring resonators overlapping a corresponding portion of one of the ground lines 546-1, 546-2. The complementary split-ring resonators 552 may be designed to cancel out high-frequency currents that would otherwise form on them, and thus may be used to allow the feed stem printed circuit board 520-1 to transmit more RF energy in the high-frequency range.

[0147] Figures 7A-7C These are schematic shaded plan views of concealed power supply spool printed circuit boards 620, 720, and 820, respectively, according to other embodiments of the present invention. The concealed power supply spool printed circuit boards 620, 720, and 820 can replace the power supply spool printed circuit board 220-1, for example in... Figure 3A The radiating element 200 is used (and the feed stem printed circuit board 220-2 will be similarly replaced with a feed stem printed circuit board similar to the feed stem printed circuit boards 620, 720, 820 but with different slits).

[0148] The power supply handle printed circuit boards 620, 720, and 820 can be used with... Figure 5The feed stem printed circuit board 420-1 is identical to the feed stem printed circuit board 620, 720, 820, but each of the feed stem printed circuit boards 620, 720, 820 further includes an open-circuit short post 660, 760, 860 connected to the ground wire 646, 746, 846 of the respective feed stem printed circuit board 620, 720, 820. The electrical length of the open-circuit short posts 660, 760, 860 can be selected such that each short post 660, 760, 860 acts as a band-stop filter. In an exemplary embodiment, the electrical length of each short post 660, 760, 860 can be between 0.2 and 0.3 of the center wavelength of a nearby radiating element (e.g., a high-frequency beamforming array 160) in order to suppress the current formed on the ground wire 646, 746, 846 of the respective feed stem printed circuit board 620, 720, 820 in response to RF radiation emitted by such radiating element.

[0149] exist Figure 7A In this embodiment, two open-circuit short posts 660-1, 660-2 extend from each grounding wire 646. The two open-circuit short posts 660-1, 660-2 share a first segment 662 and each has a second segment 664-1, 664-2 extending from the shared first segment 662. Figure 7B In one embodiment, two open-circuit short posts 760 extend from each grounding wire 746, but in this case, the open-circuit short posts 760 are spaced apart from each other and do not share a common segment. Figure 7C The embodiments are similar to Figure 7B The embodiments are shown, but the open-circuit short post 860 is in different positions and has different shapes.

[0150] Although Figures 7A-7C Each ground wire in the embodiments includes two open-circuit short posts, but it should be understood that embodiments of the invention are not limited thereto. In other embodiments, fewer (one) or more (three, four, five or more) open-circuit short posts may extend from each ground wire. It should also be understood that the number of open-circuit short posts extending from each ground wire need not be the same. Although the short posts are shown as being formed on the same side of the feed handle printed circuit board as the ground wire, it should also be understood that some or all of the short posts may be formed on the other side of the feed handle printed circuit board, or some or all of the short posts may have portions on both sides of the feed handle printed circuit board. It should also be understood that open-circuit short posts may be added to any of the feed handles according to embodiments of the invention discussed herein to further suppress the formation of current thereon in response to RF radiation emitted by nearby radiating elements.

[0151] Figure 8A and 8B This is a schematic perspective view of the stealthy coaxial cables 900 and 901 according to an embodiment of the present invention. (Refer to the above text) Figure 2A-2BAs discussed, in some passive / active antenna systems, multiple low-frequency radiating elements (and potentially mid-frequency radiating elements) can be mounted in front of a beamforming array of high-frequency radiating elements. For example, as referenced above... Figure 2A-2B As described, in some cases, the passive reflector assembly 120 of the passive base station antenna 110 of the passive / active antenna system 100 may include an opening 126, and a frequency selective surface may cover the opening 126. A low-frequency radiating element 132 may be mounted on the frequency selective surface and may be directly in front of the high-frequency radiating element 162 of the beamforming array 160 included in the active antenna module 150 of the passive / active antenna system 100. The low-frequency radiating element 132 is typically mounted on a feed board printed circuit board. To feed RF signals to the low-frequency radiating element, a pair of coaxial cables (one polarized each) are typically connected to each feed board printed circuit board. Unfortunately, these coaxial cables can be used to scatter the RF energy emitted by the beamforming array 160.

[0152] like Figures 8A-8B As shown, according to another embodiment of the invention, a coaxial cable is provided having a metamaterial structure printed on or otherwise formed on its outer protective sheath. First refer to... Figure 8A The coaxial cable 900 includes a center conductor 910, a dielectric separator 920, an outer conductor 930, and an insulated cable sheath 940. Each of these components of the coaxial cable 900 can be conventional. Additionally, a plurality of metamaterial structures 950 are formed on the cable sheath 940. Each metamaterial structure 950 may include, for example, a metallic pattern printed on the outer surface of the cable sheath 940. The metamaterial structures 950 can be designed to allow the coaxial cable 900 to transmit more RF energy in one or more frequency ranges, thereby reducing the degree to which the coaxial cable 900 scatters RF energy in these frequency ranges. In the depicted embodiment, each metamaterial structure 950 includes a complementary split-loop resonator 952. The complementary split-loop resonator 952 is arranged along the longitudinal axis of the coaxial cable 900. It should be understood that split-loop resonators or other metamaterial structures may be used in other embodiments.

[0153] exist Figure 8A In one embodiment, a single-row complementary split-ring resonator 952 is formed on the cable sheath 940. For example... Figure 8B As shown, in other embodiments, a coaxial cable 901 is provided that includes more than one row of metamaterial structures 950 that can be formed on a cable sheath 940.

[0154] Figures 9A-9CThis is a graph showing the S11 (return loss) and S12 (insertion loss) s-parameters of several conductive structures for the RF energy incident upon them. In each graph, the conductive structure is shown in the upper left corner, the s-parameters are shown in the graph, and the equivalent circuit of the metal structure is shown in the lower left corner. Port 1 (the source) can be considered as being in front of the metal structure (i.e., above the page), and port 2 can be considered as being behind the metal structure (i.e., behind the page). The S11 curve in each graph shows the amount of energy measured at port 1 in response to the RF signal emitted from port 1 toward the conductive structure (i.e., the percentage of emitted RF energy reflected back to port 1) as a function of frequency. The S12 curve in each graph shows the amount of energy measured at port 2 in response to the RF signal emitted from port 1 toward the conductive structure (i.e., the percentage of emitted RF energy transmitted through / around the conductive structure) as a function of frequency.

[0155] like Figure 9A As shown, a wide conductive trace can be viewed as a series resistor-inductor (RL) circuit that will provide a high-pass response. Figure 9A As shown in the S12 curve in the graph, the wide trace transfers an increasing percentage of incident RF energy with increasing frequency and generally has a high-pass response, although with very poor selectivity (i.e., there is no abrupt change in the S11 or S12 response, but rather the transmission characteristics change very gradually with frequency). The wide trace reflects almost all of the incident energy in the 0.5–4.0 GHz frequency range, but at higher frequencies (not shown in the graph), a non-negligible amount of RF energy begins to transfer to port 2.

[0156] refer to Figure 9B The inductance L of a series resistor-inductor (RL) circuit can be increased by reducing the width of the conductive trace. The increased inductance is used to shift the response to a lower frequency, causing the circuit to start at a higher frequency than... Figure 9A In circuits where lower frequencies carry a larger portion of the incident RF energy, for example, Figure 9B It shows that more than 10% of the RF energy is delivered at 4.0 GHz.

[0157] like Figure 9C As shown, a capacitor (C) is added in parallel to a series resistor-inductor (RL) circuit formed by the narrow trace by adding short metal pillars on each side of the narrow trace. This allows the circuit to have a bandpass response. As shown in the figure, null values ​​appear in the return loss (S11) curve in the 3.4-4.0 GHz frequency range, indicating that within this frequency range, Figure 9C The structure shown on the upper left may be relatively invisible or "stealthy" for RF energy.

[0158] As discussed above, the dual grounding wires included in the feed stem of a lower-frequency radiating element can potentially be used to scatter RF energy emitted by a nearby higher-frequency radiating element, since the grounding wires can resonate within the operating frequency band of the higher-frequency radiating element and / or can reflect RF energy. By adding one or more short metal posts running parallel to one or more sections of the grounding wires, a parallel LC circuit can be created, which can be tuned to have a bandpass response in the operating frequency band of the higher-frequency radiating element, thereby allowing the grounding wires to transmit more RF energy in the operating frequency band of the higher-frequency radiating element. According to another embodiment of the invention, lower-frequency radiating elements using this technique are provided such that the feed stems of these lower-frequency radiating elements are stealthy within a suitable frequency range.

[0159] Figures 10A-10E The design of the feed handle 1010 of the radiating element according to another embodiment of the invention is illustrated schematically. In particular, Figure 10A This is a schematic shaded side view of the power supply handle 1010. Figure 10B This is a schematic shaded perspective view of the concealed portion of the grounding wire included on one of the power supply handle printed circuit boards of the power supply handle 1010. Figure 10C It is along Figure 10B A schematic cross-sectional view taken from line 10C-10C. Figure 10D This is a schematic shaded perspective view of another hidden portion of the grounding wire included on one of the feed handle printed circuit boards of the feed handle 1010. Finally, Figure 10E It is along Figure 10D A schematic cross-sectional view taken from line 10E-10E. Any suitable dipole radiator (e.g., referenced above). Figure 1A The described dipole radiator 70 can be mounted on the feed handle 1010 to form a lower frequency radiating element. The lower frequency radiating element including the feed handle 1010 can, for example, be a low-frequency radiating element configured to operate in the frequency range of 696-960 MHz.

[0160] refer to Figure 10A The feed handle 1010 includes a first feed handle printed circuit board and second feed handle printed circuit boards 1020-1 and 1020-2. Each feed handle printed circuit board 1020 has a base and a distal end positioned in front of the base. A dipole radiator of the radiating element is mounted at the distal end of the feed handle printed circuit board 1020 (the distal end is...). Figure 10A (The top of the middle). The first power supply printed circuit board and the second power supply printed circuit boards 1020-1, 1020-2 include corresponding slits similar to or the same as the slits in the power supply printed circuit board 220 (see above). Figures 3A-3B Therefore, further description of these slits will be omitted here.

[0161] Each power supply stem printed circuit board 1020 is implemented using a printed circuit board including a corresponding dielectric substrate 1022. Figure 10A In (and as described below) Figure 11 (In the figure), the dielectric substrate 1022 for the first power feed handle printed circuit board 1020-1 is omitted for simplification, but the dielectric substrate 1022 for the second power feed handle printed circuit board 1020-2 is shown. A first metallization pattern and second metallization patterns 1024-1, 1024-2 are disposed on the respective main surfaces of the dielectric substrate 1022 for the first power feed handle printed circuit board 1020-1. Figure 10A This is a shaded view of a first metallization pattern 1024-1 on the back side of a dielectric substrate 1022 shown in dashed lines.

[0162] like Figure 10A As shown, the first metallization pattern 1024-1 includes a dual-line transmission line structure comprising a first metal ground wire and second metal ground wires 1046-1, 1046-2 extending from the base of the first feed handle printed circuit board 1020-1 to its distal end. Each ground wire 1046-1, 1046-2 is coupled to a ground conductor (not shown) of a first RF transmission line connected to the feed handle 1010. The first ground wire and the second ground wire 1046-1, 1046-2 may each have an electrical length of approximately ¼ of the center wavelength of the radiating element of the feed handle 1010. The front portion of each ground wire 1046-1, 1046-2 includes a corresponding series LC circuit 1060-1, 1060-2, which may be connected to... Figure 6 The series LC circuits 560-1 and 560-2 included in the power supply handle printed circuit board 520 are the same. (See reference...) Figure 6 As discussed, the LC circuit formed in the front portion of grounding wires 1046-1 and 1046-2 can be tuned to transmit RF energy in the low-frequency operating band while rejecting (blocking) RF energy in the operating bands of other nearby radiating elements operating in different frequency bands (e.g., the operating band of the nearby beamforming array 160). Therefore, the LC circuit can act as a filter blocking high-frequency currents. The LC circuit 1060 can also be designed to provide appropriate impedance matching between the RF transmission lines and the dipole radiators in the feed stem printed circuit boards 1020-1 and 1020-2.

[0163] As from Figure 10AIt can also be seen that the first and second sections 1048-1 and 1048-2 of the second grounding wire 1046-2 are narrower than the first grounding wire 1046-1 and narrower than the rest of the second grounding wire 1046-2. Additionally, the first and second metal short posts 1080-1 and 1080-2 are positioned on opposite sides of the first section 1048-1 of the second grounding wire 1046-2. The third metal short post 1080-3 is positioned behind the first metal short post 1080-1, and the fourth metal short post 1080-4 is positioned behind the second metal short post 1080-2. The third and fourth metal short posts 1080-3 and 1080-4 are positioned on opposite sides of the second section 1048-2 of the second grounding wire 1046-2. Compared to the first ground wire 1046-1 (and compared to the remainder of the second ground wire 1046-2), the width of the first and second segments 1048-1, 1048-2 of the second ground wire 1046-2 is narrowed to provide space for the first metal short posts 1080-1 to the fourth metal short posts 1080-4 in the first metallization pattern 1024-1 on the power supply handle printed circuit board 1020-1. The first metal short posts 1080-1 to the fourth metal short posts 1080-4 are part of the first metallization pattern 1024-1. Reference will be made below. Figure 10B-10E The function and operation of the metal short column 1080 will be discussed in more detail.

[0164] The second metallization pattern 1024-2 includes a signal line 1040 coupled to a signal conductor (not shown) of an RF transmission line that powers the first feed handle printed circuit board 1020-1. The signal line 1040 extends forward from the base of the first feed handle printed circuit board 1020-1 and travels approximately two-thirds of the distance toward its distal end. Then, the signal line 1040 passes through a first 90°... 0 The direction changes so that it extends laterally across the first side of the power supply spool printed circuit board 1020-1. Finally, the signal line 1040 passes through the second 90... 0 The signal line 1040 is diverted to extend rearward toward the base of the first feed stem printed circuit board 1020-1, thereby dividing the signal line 1040 into a forward extending segment, a lateral extending segment, and a rearward extending segment. The forward extending segment overlaps with the first ground line 1046-1. The lateral extending segment extends from the end of the forward extending segment to cross the gap 1036 (i.e., the unmetallized area) between the first ground line and the second ground line 1046-1, 1046-2. The lateral extending segment partially overlaps with both the first ground line 1046-1 and the second ground line 1046-2. The rearward extending segment overlaps with the second ground line 1046-2.

[0165] The second metallization pattern 1024-2 also includes four additional metal short posts 1090-1 to 1090-4, wherein the first and second additional metal short posts 1090-1, 1090-2 are positioned on opposite sides of the rearward extension segment of the signal trace 1040, and the third and fourth additional metal short posts 1090-3, 1090-4 are positioned immediately behind the corresponding first and second additional metal short posts 1090-1, 1090-2. Reference will be made below. Figure 10B-10E The function and operation of the additional metal short post 1090 are discussed in more detail. The signal trace 1040, together with the first ground line and the second ground lines 1046-1, 1046-2, form the RF feed line 1016-1, which transmits RF signals between the RF transmission line (not shown) for the feed network of the radiating element including the feed handle 1010 and the dipole radiator of the radiating element.

[0166] Figure 10B This is a schematic perspective view of a small portion of the first feed handle printed circuit board 1020-1 near the far end of signal line 1040. Figure 10C It is along Figure 10B A schematic cross-sectional view taken from line 10C-10C.

[0167] refer to Figures 10A-10E The first and second metal short pillars 1080-1 and 1080-2 are formed in the same metallization layer (layer 1024-1) as the second grounding wire 1046-2, and extend parallel to and very close to the first (narrowed) segment 1048-1 of the second grounding wire 1046-2. Therefore, the first segment 1048-1 of the second grounding wire 1046-1 and the first and second metal short pillars 1080-1 and 1080-2 form a first resonant structure 1070-1, which has the features described above. Figure 9C The design of the resonant structure is discussed above. The lengths of the first and second metal short pillars 1080-1 and 1080-2 can be configured such that the resonant structure 1070-1 exhibits a bandpass response within a desired frequency range (e.g., the frequency range of a nearby higher-frequency radiating element). Similarly, the third and fourth metal short pillars 1080-3 and 1080-4, together with the second ground wire 1046-2, are also formed in the first metallization layer 1024-1, extending parallel to and very close to the second (narrowed) segment 1048-2 of the second ground wire 1046-2. Therefore, the second segment 1048-2 of the second ground wire 1046-1 and the third and fourth metal short pillars 1080-3 and 1080-4 form the second resonant structure 1070-2, which also has the characteristics described above. Figure 9CThe design of the resonant structure is discussed. The lengths of the first and second metal short pillars 1080-1 and 1080-2, as well as the lengths of the third and fourth metal short pillars 1080-3 and 1080-4, can be set such that the first and second resonant structures 1070-1 and 1070-2, as discussed above, each exhibit a bandpass response within a desired frequency range (e.g., the frequency range of a nearby higher-frequency radiating element). In other words, by narrowing the section of the second ground wire 1046-2 and positioning the metal short pillar 1080 on either side, it is possible to... Figure 10B and 10D The diagram of the grounding wire shows more about the operating frequency band of the nearby radiating elements.

[0168] Unfortunately, reducing the width of the first and second segments 1048-1, 1048-2 of the second ground line 1046-2 reduces the impedance matching between the RF transmission line 1016-1 and the dipole radiator mounted on the first feed stem printed circuit board 1020-1. This can increase the return loss of lower frequency radiating elements, thereby reducing their operating bandwidth. To counteract this impedance degradation, additional metal pillars 1090 are provided in the second metallization layer 1024-2. The additional metal pillars 1090 may be, for example, identical to metal pillar 1080, and in some embodiments may exactly overlap with metal pillar 1080. As can also be seen, plated vias 1086 extend through a dielectric substrate 1022 that connects the current of the first metal pillars 1080-1 to the fourth metal pillars 1080-4 to the first additional metal pillars 1090-1 to the fourth additional metal pillars 1090-4.

[0169] like Figure 10B and 10C As shown, a portion of the signal line 1040-1 may extend between the first additional metal post and the second additional metal posts 1090-1, 1090-2. Figure 10D and 10E As shown, signal line 1040-1 does not extend between the third additional metal short post and the fourth additional metal short posts 1090-3 and 1090-4. Figure 10B-10C A portion of the first feed stem printed circuit board 1020-1 shown can be considered as the first unit of the frequency selection surface, and Figure 10D-10E A portion of the first feed handle printed circuit board 1020-1 shown can be considered as the second unit of the frequency selection surface.

[0170] Therefore, according to another embodiment of the invention, a radiating element is provided, the radiating element comprising: a feed handle 1010 having a signal line 1040, a ground line 1046-2, and a first metal post 1080-1 extending parallel to a first segment 1048-1 of the ground line 1046-2; and a radiator (not shown) mounted on the feed handle 1010. The first metal post 1080-1 is configured to be capacitively coupled to the first segment 1048-1 of the ground line 1046-2.

[0171] According to an additional embodiment of the invention, a radiating element is provided, comprising: a feed handle 1010 having a signal line 1040 and a ground line 1046-2; and a radiator mounted on the feed handle 1010. In these radiating elements, a first segment 1048-1 of the ground line 1046-2 is part of a resonant circuit 1070-1 configured to have a bandpass response within a preselected frequency range.

[0172] According to other embodiments of the present invention, a radiating element is provided, the radiating element comprising a feed stem printed circuit board 1020-1 having a signal line 1040, a ground line 1046-2, first and second metal short posts 1080-1, 1080-2 on opposite sides of a first segment 1048-1 of the ground line 1046-2, and first and second additional metal short posts 1090-1, 1090-2 overlapping the corresponding first and second metal short posts 1080-1, 1080-2. The radiating element may further include a radiator mounted on a feed stem 1010.

[0173] In some embodiments, signal line 1040, ground line 1046-2, and first metal post 1080-1 are implemented on a power supply shank printed circuit board 1020-1. In some embodiments, the first metal post 1080-1 is not currently connected to ground line 1046-2 or signal line 1040. In some embodiments, the width of a first segment 1048-1 of ground line 1046-2 is less than half the width of another segment of ground line 1046-2.

[0174] In some embodiments, the radiating element further includes a second metal post 1080-2 extending parallel to the first segment 1048-1 of the ground wire 1046-2, wherein the second metal post 1080-2 is configured to capacitively couple with the first segment 1048-1 of the ground wire 1046-2. In some embodiments, the first metal post 1080-1 is on a first side of the first segment 1048-1 of the ground wire 1046-2, and the second metal post 1080-2 is on a second side of the first segment 1048-1 of the ground wire 1046-2 opposite to the first side. In some embodiments, the first metal post 1080-1, the second metal post 1080-2, and the first segment 1048-1 of the ground wire 1046-2 are all on the first metallization layer 1024-1 of the power supply stem printed circuit board 1020-1.

[0175] In some embodiments, the radiating element further includes a third metal short post and a fourth metal short post 1080-3, 1080-4, the third metal short post and the fourth metal short post extending parallel to the second segment 1048-2 of the grounding wire 1046-2 and configured to be capacitively coupled to the second segment 1048-2 of the grounding wire 1046-2.

[0176] In some embodiments, the radiating element further includes a first additional metal short post 1090-1 overlapping with the first metal short post 1080-1 and a second additional metal short post 1090-2 overlapping with the second metal short post 1080-2, wherein the first additional metal short post and the second additional metal short posts 1090-1, 1090-2, and at least a first portion of the signal line 1040 are all on the second metallization layer 1024-2 of the power supply spool printed circuit board 1020-1, the second metallization layer being different from the first metallization layer 1024-1. In some embodiments, a first conductive via 1086-1 in the power supply spool printed circuit board 1020-1 connects the first metal short post 1080-1 to the first additional metal short post 1090-1, and a second conductive via 1086-2 in the power supply spool printed circuit board 1020-1 connects the second metal short post 1080-2 to the second additional metal short post 1090-2. In some embodiments, the first portion of the signal line 1040 is between the first additional metal post and the second additional metal post 1090-1, 1090-2.

[0177] In some embodiments, the first metal short post 1080-1 and the first segment 1048-1 of the ground wire 1046-2 together comprise at least a portion of an inductor-capacitor circuit 1070-1 having a bandpass filter response. In some embodiments, the radiating element is part of a base station antenna, and the base station antenna includes a second radiating element having an operating frequency band, wherein the frequency having the highest transmission level in the bandpass filter response is within the operating frequency band.

[0178] Simulations show that the feed handle 1010 exhibits good stealth performance across the entire 3.4-4.0 GHz frequency band. For example, assuming an array of radiating elements in the higher frequency band (3.4-4.0 GHz) is mounted behind the feed handle 1010 and is not electronically scanned (0 in the azimuth plane)... 0 (Scanning angle), then the feed stem 1010 can exhibit good stealth performance across the entire 3.4-4.0 GHz frequency band. When the array of higher frequency radiating elements is electronically scanned to 45 degrees in the azimuth plane... 0 The same results were observed. Simulations show that the return loss of RF transmission line 1016-1 is better than -11.85dB across the entire 696-960MHz operating frequency band, and the return loss performance can be improved to more than -15dB through optimization.

[0179] Figure 11 This is a schematic side view of the feed handle 1110 of a radiating element according to other embodiments of the present invention. The feed handle 1110 can be coupled with... Figures 10A-10E The feed handles 1010 are almost identical, so the following discussion will focus only on the differences between the two feed handles.

[0180] like Figure 11 As shown, the first ground line 1146-1 formed in the first metallization pattern 1024-1 of the first feed handle printed circuit board 1120-1 of the feed handle 1110 includes a narrowing section. The first metallization pattern 1024-1 also includes a fifth and a sixth metal post 1080-5, 1080-6 formed on opposite sides of the narrowing section of the first ground line 1146-1. The narrowing section of the first ground line 1146-1 and the fifth and sixth metal posts 1080-5, 1080-6 form a third resonant structure 1070-3. The third resonant structure 1070-3 can be configured to allow more RF energy in the operating frequency band of nearby higher frequency radiating elements to pass through the first ground line 1146-1. The second metallization pattern 1024-2 also includes a fifth and a sixth additional metal post 1090-5, 1090-6 formed on opposite sides of the signal line 1040.

[0181] Figure 12A This is a schematic shaded side view of a mid-frequency radiating element 1200 according to an additional embodiment of the present invention. Figure 12A As shown, the radiating element 1200 includes a feed handle 1210 and a dipole radiator printed circuit board 1270. The dipole radiator printed circuit board 1270 includes a first dipole radiator and a second dipole radiator arranged as a first dipole radiator and a second dipole radiator (in... Figure 12A The first to fourth dipole arms (not visible in the middle) Figure 12A(Not visible in the text). The first and second dipole radiators can be any suitable dipole radiator design. For example, the first and second dipole radiators can be referenced above. Figure 1A The dipole radiators 70-1 and 70-2 discussed are the same.

[0182] The feed handle 1210 is formed as a single feed handle printed circuit board 1220. The feed handle printed circuit board 1220 includes a first RF transmission line 1216-1 feeding a first dipole radiator and a second RF transmission line 1216-2 feeding a second dipole radiator. The feed handle printed circuit board 1220 includes a dielectric substrate 1222 having a first metallization pattern and a second metallization pattern formed on its main surface. Ground lines 1246-1 and 1246-2 for the first RF transmission line 1216-1 and a signal line 1240-2 (mainly) for the second RF transmission line 1216-2 are formed in the second metallization pattern, while ground lines 1246-3 and 1246-4 for the second RF transmission line 1216-2 and a signal line 1240-1 (mainly) for the first RF transmission line 1216-1 are formed in the first metallization pattern. Unlike the remainder of the corresponding first and third ground wires 1246-1, 1246-3, the small front portion of the first and third ground wires 1246-1, 1246-3 is formed in another of the first and second metallization patterns. Various designs of cross-dipole radiating elements with single-fed stem printed circuit boards are disclosed in PCT patent application number PCT / CN2022 / 104848 (“'848 application”), the entire contents of which are incorporated herein by reference.

[0183] The power supply stem printed circuit board 1220 differs from the power supply stem printed circuit board disclosed in application '848' in that the split-ring resonator 1290 is provided with a first metallization pattern and a second metallization pattern. Specifically, the first metallization pattern includes a first split-ring resonator and second split-ring resonators 1290-1, 1290-2 for concealing a portion of the second ground wire 1246-2, and the second metallization pattern includes a third split-ring resonator and fourth split-ring resonators 1290-3, 1290-4 for concealing a portion of the fourth ground wire 1246-4. The split-ring resonator 1290 is used to interact with... Figure 5 The complementary split-ring resonator 452 in the radiating element 400 is used to make the second ground wire and the fourth ground wire 1246-2 and 1246-4 invisible in the same way as the corresponding ground wires 446-1 and 446-2, so further description of them will be omitted here.

[0184] Figure 12BThis is a schematic shaded side view of a mid-frequency radiating element 1300 according to another embodiment of the present invention. Figure 12B As shown, the radiating element 1300 includes a feed handle 1310, the feed handle being connected to... Figure 12A The feed handle 1210 of the radiating element 1200 is similar in that the feed handle 1310 is formed using a single feed handle printed circuit board 1320, which includes a first RF transmission line and second RF transmission lines 1316-1, 1316-2 feeding a pair of dipole radiators. However, the split-ring resonator 1290 included on the feed handle 1210 is omitted in the radiating element 1300 and replaced by a plurality of metal short posts 1380 and additional metal short posts 1390 formed adjacent to ground lines 1346-1 to 1346-4. Specifically, metal short posts 1380-1 and 1380-2 are disposed on opposite sides of the first grounding wire 1346-1, metal short posts 1380-2 and 1380-3 are disposed on opposite sides of the second grounding wire 1346-2, metal short posts 1380-4 and 1380-5 are disposed on opposite sides of the third grounding wire 1346-3, and metal short posts 1380-5 and 1380-6 are disposed on opposite sides of the fourth grounding wire 1346-4. Metal short posts 1380-1 to 1380-3 are part of the second metallization pattern of the power supply handle printed circuit board 1320, while metal short posts 1380-4 to 1380-6 are part of the first metallization pattern of the power supply handle printed circuit board 1320. Additional metal short posts 1390-1 and 1390-2 can be disposed on the first metallized pattern to exactly overlap with metal short posts 1390-1 and 1390-2, respectively, and additional metal short posts 1390-3 and 1390-4 can be disposed in the second metallized pattern to exactly overlap with metal short posts 1380-5 and 1380-6, respectively. Electroplated through-holes (not shown) can electrically connect each metal short post 1380 to a corresponding one of the additional metal short posts 1390 that overlap with the metal short post. Additionally, electroplated through-hole 1386 can also electrically connect metal short post 1380-3 to metal short post 1380-4.

[0185] The metal short post 1380 can add capacitance, which, when inductively coupled to the ground line 1346, can form a resonant circuit with a bandpass filter response. The resonant circuit can be tuned to have a passband within the operating frequency band of one or more nearby higher-frequency radiating elements in the same way that the metal short post 1080 of the feed stem 1010 is used to conceal its ground line. Additional metal short posts 1390 and plated vias 1386 can be provided to better impedance match the RF transmission line 1316 to the dipole radiator. Therefore, Figure 12B The above reference is shown. Figures 10A-10EThe techniques described can be used for radiating elements operating in other frequency bands and / or for radiating elements with different feed stem designs.

[0186] Figure 13 This is a schematic perspective view of a stealthy coaxial cable 1400 according to another embodiment of the present invention. (Reference) Figure 13 The coaxial cable 1400 includes a center conductor 1410, a dielectric spacer 1420, an outer conductor 1430, and an insulated cable sheath 1440. Each of these components of the coaxial cable 1400 can be conventional. Additionally, the coaxial cable 1400 includes a plurality of spaced-apart metal posts 1450 formed above the outer sheath 1440. The metal posts 1450 can be capacitively coupled to the outer conductor 1430 to form corresponding resonant circuits 1460 with a bandpass response. The bandpass response of these resonant circuits 1460 can be tuned to operate within the frequency band of nearby radiating elements (not shown), which can be used to make the coaxial cable stealthy with respect to RF energy in the operating frequency band of these nearby radiating elements. Because the outer conductor 1430 of the coaxial cable 1400 may be relatively large, the inductance of the resonant circuits 1460 may be relatively small, which may result in a narrower passband. Therefore, this technique is particularly suitable for stealthing coaxial cables located near higher-frequency radiating elements with a narrower operating frequency band.

[0187] The metal stub 1450 may include a metal sleeve 1450 that is directly mounted on the cable sheath 1440. The metal sleeve 1450 may have an annular shape.

[0188] It should be understood that many modifications can be made to the radiating element described above without departing from the scope of the invention. For example, the radiating element described above is formed using a feed stem printed circuit board. In other embodiments, other types of feed stem implementations can be used, such as metal plate feed stems. Similarly, although the dipole arm of the low-frequency radiating element described above is implemented in a dipole radiator printed circuit board, it should be understood that the embodiments of the invention are not limited thereto. For example, in other embodiments, the dipole arm can be implemented as a sheet metal dipole arm or can be implemented using other metal structures.

[0189] The radiating element according to embodiments of the present invention can be included in a multi-band base station antenna, and can reduce the amount of interaction between arrays in different frequency bands. A base station antenna including a radiating element according to embodiments of the present invention can be used as a sector antenna, for example, in the aforementioned cellular communication system.

[0190] 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 thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Throughout the text, the same reference numerals denote the same elements.

[0191] 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, without departing from the scope of the invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0192] It will be understood that when an element is described as being “on” another element, that element may be directly on the other element, or there may be intermediate elements present. Conversely, when an element is described as being “directly on” another element, there are no intermediate elements present. It will also be understood that when an element is described as being “connected” or “coupled” to another element, that element may be directly connected or coupled to the other element, or there may be intermediate elements present. Conversely, when an element is described as being “directly connected” or “directly coupled” to another element, there are no intermediate elements present. Other terms used to describe relationships between elements should be interpreted in a similar manner (i.e., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).

[0193] Relative terms, such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical”, may be used herein to describe the relationship of one element, layer, or region to another element, layer, or region, as illustrated in the accompanying drawings. It should be understood that these terms are intended to cover different orientations of the device other than those depicted in the accompanying drawings.

[0194] In this article, the term "basically" means within + / - 10%.

[0195] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the terms “comprising,” “including,” and / or “having” as used herein mean the presence of the stated features, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

[0196] 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. A radiating element, comprising: A feed handle having a signal line, a first ground line, and a ring-based metamaterial resonator; as well as A radiator mounted on the feed handle.

2. The radiating element of claim 1, wherein the ring-based metamaterial resonator overlaps with the first ground wire.

3. The radiating element of claim 2, wherein the ring-based metamaterial resonator comprises a complementary split-ring resonator.

4. The radiating element of claim 2, wherein the ring-based metamaterial resonator comprises a split-ring resonator.

5. The radiating element according to any one of claims 1-4, wherein the feed handle comprises a first plurality of ring-based metamaterial resonators, wherein the ring-based metamaterial resonator is one of the first plurality of ring-based metamaterial resonators, and the first plurality of ring-based metamaterial resonators overlaps with the first ground wire by at least 50%.

6. The radiating element of claim 5, wherein the feed handle further comprises a second ground wire and a second plurality of ring-based metamaterial resonators that overlap at least 50% with the second ground wire.

7. The radiating element of claim 6, wherein the feed stem comprises a feed stem printed circuit board having a dielectric substrate having a first metallization pattern and a second metallization pattern on its opposing first and second main surfaces, wherein the signal line and the ring-based metamaterial resonator are at least a portion of the first metallization pattern, and the first ground line and the second ground line are at least a portion of the second metallization pattern.

8. The radiating element of claim 7, wherein the signal line comprises a first segment overlapping the first grounding wire, a third segment overlapping the second grounding wire, and a second segment connecting the first segment to the third segment.

9. The radiating element of claim 8, wherein the signal line is between the first plurality of ring-based metamaterial resonators, and the second plurality of ring-based metamaterial resonators overlap with the second ground line.

10. The radiating element according to any one of claims 1-4, wherein the feed handle comprises a feed handle printed circuit board having: a first dielectric substrate having a first metallization pattern thereon; a second dielectric substrate having a third metallization pattern thereon; and a second metallization pattern positioned between the first dielectric substrate and the second dielectric substrate, wherein the ring-based metamaterial resonator is part of the first metallization pattern, the signal line is at least a part of the second metallization pattern, and the first ground line is part of the third metallization pattern.

11. The radiating element according to any one of claims 1-4, wherein the radiator is mounted on the front end of the feed handle, and the ring-based metamaterial resonator overlaps with a portion of the first ground wire positioned in front of the signal line.

12. A base station antenna, comprising: A first radiating element, the first radiating element being configured as the radiating element according to claim 1; as well as A second radiating element, configured to operate at a higher frequency band than the first radiating element. The ring-based metamaterial resonator is configured to operate as a bandpass filter having a passband that includes at least a portion of the higher operating frequency band.

13. The base station antenna according to claim 12, wherein the first radiating element is mounted in front of the second radiating element.

14. A radiating element, comprising: A feed stem printed circuit board, the feed stem printed circuit board comprising at least: a first dielectric substrate; a first metallization pattern extending in the longitudinal direction of the feed stem printed circuit board on a first outer surface of the dielectric substrate; and a second metallization pattern including a plurality of ring-based metamaterial resonators; and Radiator.

15. The radiating element of claim 14, wherein the first metallization pattern comprises a first ground wire and a second ground wire.

16. The radiating element of claim 15, wherein the second metallization pattern further comprises a signal line positioned between a first ring-based metamaterial resonator and a second ring-based metamaterial resonator among the plurality of ring-based metamaterial resonators.

17. The radiating element of claim 15, wherein the plurality of ring-based metamaterial resonators comprises a first plurality of ring-based metamaterial resonators and a second plurality of ring-based metamaterial resonators.

18. The radiating element of claim 17, wherein the first plurality of ring-based metamaterial resonators overlap with the first ground wire.

19. The radiating element according to any one of claims 14-18, wherein the plurality of ring-based metamaterial resonators comprises a plurality of complementary split-ring resonators.

20. The radiating element according to any one of claims 14-18, wherein the plurality of ring-based metamaterial resonators comprises a plurality of split-ring resonators.

21. The radiating element of claim 16, wherein the second metallization pattern is on the second outer surface of the first dielectric substrate.

22. The radiating element of claim 15, wherein the feed stem printed circuit board further comprises a second dielectric substrate, wherein the second metallization pattern is on the outer surface of the second dielectric substrate, and the feed stem further comprises a signal line, the signal line being part of a third metallization pattern positioned between the first dielectric substrate and the second dielectric substrate.

23. The radiating element of claim 22, wherein the signal line comprises a first segment overlapping the first grounding wire, a third segment overlapping the second grounding wire, and a second segment connecting the first segment to the third segment.

24. The radiating element of claim 23, wherein the plurality of ring-based metamaterial resonators comprises a first plurality of ring-based metamaterial resonators and a second plurality of ring-based metamaterial resonators, wherein the first plurality of ring-based metamaterial resonators overlaps with the first ground wire, and the second plurality of ring-based metamaterial resonators overlaps with the second ground wire.

25. The radiating element of claim 16, wherein the signal line, the first ground line, and the second ground line together comprise an RF feed line.

26. A base station antenna, comprising: A first radiating element, the first radiating element being configured to operate in a first operating frequency band; as well as A second radiating element, the second radiating element being configured to operate in a second operating frequency band that includes a higher frequency than the first operating frequency band; The feed stem of the first radiating element includes a radio frequency ("RF") feed line, the RF feed line including a filter having a passband in the first operating frequency band and a stopband in the second operating frequency band.

27. The base station antenna of claim 26, wherein the filter includes an inductor connected in series with the first capacitor.

28. The base station antenna of claim 27, wherein the RF feed line includes a signal line and a first ground line, and wherein the inductor is part of the first ground line.

29. The base station antenna of claim 28, wherein the inductor includes a tortuous conductive trace having an average width smaller than half the average width of the remainder of the first ground wire.

30. The base station antenna of claim 27, wherein the filter further comprises a second capacitor connected in parallel with the series combination of the inductor and the first capacitor.

31. The base station antenna of claim 28, wherein the filter is implemented on a first feed handle printed circuit board of the feed handle, and the filter is positioned between the signal line and the dipole radiator printed circuit board of the first radiating element.

32. The base station antenna according to claim 28 further includes a metamaterial structure on the printed circuit board of the first feed handle, the metamaterial structure overlapping the first ground wire.

33. The base station antenna of claim 32, wherein the metamaterial structure comprises a ring-based metamaterial resonator.

34. A coaxial cable, comprising: Central conductor; outer conductor; A dielectric spacer between the center conductor and the outer conductor; as well as An insulated cable sheath that covers the outer conductor. Multiple metamaterial structures are provided on the insulated cable sheath.

35. The coaxial cable of claim 34, wherein the metamaterial structure comprises a plurality of ring-based metamaterial resonators.

36. The coaxial cable of claim 35, wherein the plurality of ring-based metamaterial resonators comprises a plurality of complementary split-ring resonators.

37. The coaxial cable of claim 35, wherein the plurality of ring-based metamaterial resonators comprises a plurality of split-ring resonators.

38. The coaxial cable of claim 35, wherein the plurality of ring-based metamaterial resonators extend on the insulating cable sheath in the longitudinal direction of the coaxial cable.

39. The coaxial cable according to claim 35, wherein the coaxial cable is disposed in a base station antenna, the base station antenna comprising: A plurality of first radiating elements, the plurality of first radiating elements being configured to operate in a first frequency band; And a plurality of second radiating elements configured to operate in a second frequency band containing a higher frequency than the first frequency band, and the metamaterial structure configured to cancel the current in the second frequency band.

40. The coaxial cable of claim 39, wherein the coaxial cable is a feed cable for one of the first radiating elements.

41. A radiating element, comprising: A power feed handle having a signal line, a first ground line, and a first metal post extending parallel to a first segment of the first ground line, wherein the first metal post is configured to be capacitively coupled to the first ground line. as well as A radiator mounted on the feed handle.

42. The radiating element of claim 41, wherein the signal line, the first ground line, and the first metal post are implemented on a feed stem printed circuit board.

43. The radiating element of claim 42 further includes a second metal post extending parallel to a first segment of the first ground wire, wherein the second metal post is configured to be capacitively coupled to the first ground wire.

44. The radiating element of claim 43, wherein the first metal post, the second metal post, and the first section of the first ground wire are all on the first metallization layer of the power supply shank printed circuit board.

45. The radiating element according to claim 44, further comprising: A third metal post extends parallel to a second section of the first grounding wire, wherein the third metal post is configured to be capacitively coupled to the first grounding wire. as well as A fourth metal post extends parallel to a second segment of the first grounding wire, wherein the fourth metal post is configured to capacitively couple with the first grounding wire.

46. ​​The radiating element of claim 44 further comprises a first additional metal post overlapping the first metal post and a second additional metal post overlapping the second metal post, wherein the first additional metal post, the second additional metal post, and at least a first portion of the signal line are all on a second metallization layer on the power feed spool printed circuit board, which is different from the first metallization layer.

47. The radiating element of claim 46, wherein the first conductive via in the feed stem printed circuit board connects the first metal short pillar current to the first additional metal short pillar, and the second conductive via in the feed stem printed circuit board connects the second metal short pillar current to the second additional metal short pillar.

48. The radiating element of claim 46, wherein a first portion of the signal line is between the first additional metal post and the second additional metal post.

49. The radiating element of claim 41, wherein the first metal post and the first section of the first ground wire together comprise at least a portion of an inductor-capacitor circuit having a bandpass filter response.

50. The radiating element of claim 49, wherein the radiating element is part of a base station antenna, and wherein the base station antenna includes a second radiating element having an operating frequency band, and the frequency having the highest transmission level in the bandpass filter response is within the operating frequency band.

51. The radiating element of claim 41, wherein the width of the first segment of the first grounding wire is less than half the width of the second segment of the first grounding wire.

52. The radiating element of claim 41, wherein the first metal post is not currently connected to the first ground wire or the signal line.

53. The radiating element of claim 44, wherein the first metal post is on a first side of a first section of the first grounding wire, and the second metal post is on a second side of the first section of the first grounding wire opposite to the first side.

54. A radiating element, comprising: A power supply handle, the power supply handle having a signal line and a first ground line; as well as Radiator mounted on the feed handle, The first section of the first grounding wire is part of a resonant circuit configured to have a bandpass response within a preselected frequency range.

55. The radiating element of claim 54, wherein the radiating element has a first operating frequency band and is part of a base station antenna, the base station antenna further comprising a second radiating element having a second operating frequency band, and the passband of the bandpass response is at least partially within the second operating frequency band.

56. The radiating element of claim 55, wherein the feed handle further comprises a first metal post configured to couple with the first grounding capacitor.

57. The radiating element of claim 56, wherein the first metal post extends parallel to a first section of the first grounding wire.

58. The radiating element of claim 56, wherein the signal line, the first ground line, and the first metal post are implemented on a feed stem printed circuit board, and both the first segment of the first ground line and the first metal post are on a first metallization layer of the feed stem printed circuit board.

59. The radiating element of claim 58 further includes a second metal post extending parallel to a first segment of the first ground wire, wherein the second metal post is configured to be capacitively coupled to the first ground wire.

60. The radiating element of claim 59 further comprises a first additional metal post overlapping the first metal post and a second additional metal post overlapping the second metal post, wherein the first additional metal post, the second additional metal post, and at least a first portion of the signal line are all on a second metallization layer on the power feed spool printed circuit board, which is different from the first metallization layer.

61. The radiating element of claim 60, wherein the first portion of the signal line is between the first additional metal post and the second additional metal post.

62. The radiating element of claim 60, wherein a first conductive via in the feed stem printed circuit board connects the first metal short pillar current to the first additional metal short pillar, and a second conductive via in the feed stem printed circuit board connects the second metal short pillar current to the second additional metal short pillar.

63. A radiating element, comprising: A power supply spool printed circuit board, the power supply spool printed circuit board having a signal line, a first ground line, a first metal post and a second metal post on opposite sides of a first section of the first ground line, and a first additional metal post and a second additional metal post overlapping the corresponding first metal post and second metal post; and A radiator mounted on the feed handle.

64. The radiating element of claim 63, wherein the first ground wire and the first and second metal short posts are each part of a first metallization layer of the feed stem printed circuit board, and the first and second additional metal short posts are each part of a second metallization layer of the feed stem printed circuit board.

65. The radiating element of claim 64, wherein the first metal post and the second metal post are configured to be coupled to the first grounding capacitor.

66. The radiating element according to claim 65, further comprising: A third metal post extends parallel to a second segment of the first grounding wire, wherein the third metal post is configured to be capacitively coupled to the first grounding wire and is part of the first metallization layer. as well as A fourth metal post extends parallel to a second segment of the first grounding wire, wherein the fourth metal post is configured to be capacitively coupled to the first grounding wire and is part of the first metallization layer.

67. The radiating element of claim 66 further comprises a third additional metal post overlapping the third metal post and a fourth additional metal post overlapping the fourth metal post, wherein the third additional metal post and the fourth additional metal post are both portions of the second metallization layer of the feed stem printed circuit board.

68. The radiating element of claim 65, wherein a first conductive via in the feed stem printed circuit board connects the first metal short pillar current to the first additional metal short pillar, and a second conductive via in the feed stem printed circuit board connects the second metal short pillar current to the second additional metal short pillar.

69. The radiating element of claim 67, wherein the second metallization layer of the feed stem printed circuit board further includes a signal line, and at least a first portion of the signal line is between the first additional metal post and the second additional metal post.

70. The radiating element of claim 63, wherein the first metal post and the first section of the first ground wire together comprise at least a portion of an inductor-capacitor circuit having a bandpass filter response.

71. The radiating element of claim 70, wherein the radiating element is part of a base station antenna, the base station antenna including a second radiating element having an operating frequency band, and the frequency having the highest transmission level in the bandpass filter response is within the operating frequency band.

72. The radiating element of claim 63, wherein the width of the first segment of the first grounding wire is less than half the width of the second segment of the first grounding wire.

73. A coaxial cable, comprising: Central conductor; outer conductor; A dielectric spacer between the center conductor and the outer conductor; An insulated cable sheath that covers the outer conductor; as well as Multiple short metal posts are installed on the cable sheath.

74. The coaxial cable of claim 73, wherein the inductance of the metal post and the portion of the outer conductor covered by the metal post generates a resonant circuit, the resonant circuit being configured to have a bandpass response in a preselected frequency band.

75. The coaxial cable of claim 73, wherein the metal post comprises a plurality of annular metal posts.

76. The coaxial cable of claim 73, wherein the metal short posts of the plurality of metal short posts are spaced apart from each other.

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