Cross-dipole radiating element with frequency selective surface and base station antenna with such radiating element

Abstract

An antenna includes 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 including a higher frequency than the first operating frequency band. The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator is provided with a first dipole arm and a second dipole arm, and the second dipole radiator is provided with a third dipole arm and a fourth dipole arm. The first dipole arm includes a first metallic region substantially surrounding a first non-metallic interior region, and the first non-metallic inner region is configured such that a current induced on a first portion of the first metallic region by RF energy emitted by the second radiating element substantially counteracts a current induced on a second portion of the first metallic region by RF energy emitted by the second radiating element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application Serial No. 63,357,698, filed on July 1, 2022, the entire contents of which are incorporated herein by reference as if fully set forth. Background Art

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

[0004] Cellular communication systems are well known in the art. In a cellular communication system, a geographic area is divided into a series of areas called "cells" served by corresponding base stations. A base station may include one or more base station antennas configured to provide two-way radio frequency ("RF") communications with mobile users within the cell served by the base station. Typically, the base station antenna is mounted on a tower or other elevated structure, where a radiation pattern (also referred to herein as an "antenna beam") is generated by the base station antenna pointing outward. In many cases, each base station is divided into "sectors". In a common configuration, a hexagonal-shaped cell is divided into three 120° sectors in the azimuth plane, and each sector is served by one or more base station antennas that generate an antenna beam with an azimuth half-power beamwidth ("HPBW") of approximately 65°, thereby providing good coverage of the entire 120° sector. Base station antennas that provide less than omnidirectional (360°) coverage in the azimuth plane are generally referred to as "sector" base station antennas. The antenna beams formed by both omnidirectional and sector base station antennas are typically generated by linear or planar phased arrays of radiating elements included in the antenna.

[0005] To accommodate the growing volume of cellular traffic, cellular operators have added cellular services in a variety of new frequency bands. While in some cases a single array of so-called "wideband" or "ultra-wideband" radiating elements can be used to provide service in multiple frequency bands, in other cases different arrays of radiating elements must be used to support service in different frequency bands.

[0006] As the number of frequency bands has proliferated, and as increased sectorization has become more common (e.g., dividing a cell into six, nine, or even twelve sectors), the number of base station antennas deployed at a typical base station has increased significantly. However, there is often a limit to the number of base station antennas that can be deployed at a given base station due to, for example, local zoning regulations and / or weight and wind load constraints on the antenna tower. In order to increase capacity without further increasing the number of base station antennas, so-called multi-band base station antennas have been introduced that include multiple arrays of radiating elements. Multi-band base station antennas are now being developed that include arrays that operate in three (or more) different frequency bands, and typically multiple sub-bands in one or more of those frequency bands. For example, base station antennas are now being deployed that include two linear arrays of "low-band" radiating elements operating in some or all of the 694-960 MHz band, two linear arrays of "mid-band" radiating elements operating in some or all of the 1427-2690 MHz band, and one or more multi-column (planar) arrays of "high-band" radiating elements operating in some or all of higher frequency bands such as the 3.3-4.2 GHz band. Unfortunately, the different arrays can interact with each other, which can make it challenging to implement such multi-band antennas while also meeting customer requirements related to the size (particularly width) of the base station antenna. Summary of the invention

[0007] According to an embodiment of the present invention, an antenna (e.g., a base station antenna) is provided, the antenna comprising: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing a frequency higher than the first operating frequency band. The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, and the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm comprises a first metal region substantially surrounding a first non-metallic inner region, and the first non-metallic inner region is configured so that a current induced on a first portion of the first metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the first metal region by RF energy emitted by the second radiating element.

[0008] In some embodiments, the first metallic region may be a closed loop that completely surrounds the first non-metallic interior region.

[0009] In some embodiments, the first non-metallic interior region may include first and second grooves in the first metallic region from which metal is omitted, and a longitudinal axis of the first groove may intersect a longitudinal axis of the second groove at an angle of 90°.

[0010] In some embodiments, the first radiating element may be a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and the first slot may extend in the direction of the first linear polarization and the second slot may extend in the direction of the second linear polarization.

[0011] In some embodiments, the second dipole arm may include a second metal region substantially surrounding a second non-metallic interior region, and the second non-metallic interior region may be configured such that a current induced on a first portion of the second metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by RF energy emitted by the second radiating element. In some embodiments, the second non-metallic interior opening may include a third slot and a fourth slot in the second metal region from which metal is omitted, and a longitudinal axis of the third slot may intersect a longitudinal axis of the fourth slot at an angle of 90°. In some embodiments, the first slot and the third slot may be co-linear. In some embodiments, the second slot and the fourth slot may extend parallel to each other.

[0012] In some embodiments, the first non-metallic interior region may include a central opening and a first auxiliary opening and a second auxiliary opening extending outwardly from the central opening. In some embodiments, the first auxiliary opening and the second auxiliary opening may include a first co-linear segment and a second co-linear segment of a first slot extending through the central opening. In some embodiments, the central opening may also include a third auxiliary opening and a fourth auxiliary opening extending outwardly from the central region, and the third auxiliary opening and the fourth auxiliary opening may be a third co-linear segment and a fourth co-linear segment of a second slot extending through the central opening. In some embodiments, the first slot may intersect the second slot at an angle of 90°.

[0013] In some embodiments, the first dipole arm may have a square outer perimeter, and the first slot and the second slot may extend along respective diagonals of the square outer perimeter.

[0014] In some embodiments, the first non-metallic interior region may be a central opening and a plurality of auxiliary openings extending radially outward from the central opening. In some embodiments, the plurality of auxiliary openings may include a first slot and a second slot, the first slot including a first segment and a second segment that are collinear and radially extend from the central opening, and the second slot including a third segment and a fourth segment that are collinear and radially extend from the central opening. In some embodiments, the first segment to the fourth segment may define a cross shape. In some embodiments, the plurality of auxiliary openings may also include a plurality of satellite openings, and the distal end of each of the first segment to the fourth segment may terminate at a corresponding one of the satellite openings. In some embodiments, the width of each of the first segment to the fourth segment is less than the width of the corresponding one of the satellite openings. In some embodiments, each satellite opening may be a rectangular opening.

[0015] In some embodiments, the first metallic region may be a piece of metal sheet and the first non-metallic interior region may be an opening punched into the piece of metal sheet.

[0016] In some embodiments, each of the first to fourth dipole arms can have a substantially rectangular perimeter, except for first and second recesses on respective first and second sides of the substantially rectangular perimeter. In some embodiments, the first recess on the first dipole arm can face the first recess on the second dipole arm, and the second recess on the first dipole arm can face the second recess on the fourth dipole arm.

[0017] In some embodiments, the first to fourth dipole arms may each have a base adjacent to a feed structure of the first radiating element and a distal end opposite the base. In some embodiments, the first radiating element may further include at least one feed handle extending substantially perpendicular to a plane defined by the radially extending slot.

[0018] In some embodiments, the first to fourth dipole arms may be configured to be substantially transparent to RF signals in the second operating frequency band.

[0019] In some embodiments, the shape of the first non-metallic interior region can be configured to cause the first metal region to act as a frequency selective surface that conducts current excited in response to RF energy in the first operating frequency band while counteracting current excited in response to RF energy in the second operating frequency band.

[0020] According to another embodiment of the present invention, an antenna is provided, the antenna comprising: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing higher frequencies than the first operating frequency band. The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, the second dipole radiator having a third dipole arm and a fourth dipole arm, and the first dipole arm comprising a first metal region substantially surrounding a non-metallic inner region, and the shape of the non-metallic inner region is configured to cause the first metal region to act as a frequency selective surface, the frequency selective surface conducting a current excited in response to RF energy in the first operating frequency band while counteracting a current excited in response to RF energy in the second operating frequency band.

[0021] In some embodiments, the first metallic region may be a closed loop that completely surrounds the first non-metallic interior region.

[0022] In some embodiments, the first non-metallic interior region may include a first slot and a second slot in the first metal region from which metal is omitted, and a longitudinal axis of the first slot intersects a longitudinal axis of the second slot at an angle of 90°. In some embodiments, the first radiating element may be a dual-polarized radiating element configured to transmit and receive RF energy in respective first and second orthogonal linear polarizations, and the first slot may extend in the direction of the first linear polarization, and the second slot may extend in the direction of the second linear polarization. In some embodiments, the second dipole arm may include a second metal region substantially surrounding the second non-metallic interior region, and the second non-metallic interior region may be configured such that a current induced on a first portion of the second metal region by the RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by the RF energy emitted by the second radiating element. In some embodiments, the second non-metallic interior opening may include a third slot and a fourth slot in the second metal region from which metal is omitted, and a longitudinal axis of the third slot may intersect a longitudinal axis of the fourth slot at an angle of 90°. In some embodiments, the first slot and the third slot may be collinear, and the second slot and the fourth slot may extend parallel to each other.

[0023] In some embodiments, the first non-metallic interior region may include a central opening and a plurality of auxiliary openings extending radially outward from the central opening. In some embodiments, the plurality of auxiliary openings may include a first slot and a second slot, the first slot including a first segment and a second segment that are co-linear and extend radially from the central opening, and the second slot including a third segment and a fourth segment that are co-linear and extend radially from the central opening. In some embodiments, the first segment to the fourth segment may define a cross shape. In some embodiments, the plurality of auxiliary openings may also include a plurality of satellite openings, wherein the distal end of each of the first segment to the fourth segment may terminate at a corresponding one of the satellite openings, and the width of each of the first segment to the fourth segment may be less than the width of the corresponding one of the satellite openings. In some embodiments, each satellite opening may be a rectangular opening.

[0024] In some embodiments, each of the first to fourth dipole arms can have a substantially rectangular perimeter, except for first and second recesses on respective first and second sides of the substantially rectangular perimeter. In some embodiments, the first recess on the first dipole arm can face the first recess on the second dipole arm, and the second recess on the first dipole arm can face the second recess on the fourth dipole arm.

[0025] According to some further embodiments of the present invention, an antenna is provided, the antenna comprising: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing higher frequencies than the first operating frequency band. The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm comprises a first metal region substantially surrounding a first non-metallic inner region, the first non-metallic inner region comprising a central opening and first and second auxiliary openings extending radially from the central opening.

[0026] In some embodiments, the first metallic region is a closed loop that completely surrounds the first non-metallic interior region.

[0027] In some embodiments, the first auxiliary opening and the second auxiliary opening may be first and second co-linear segments of a first slot extending through the central opening.

[0028] In some embodiments, the central opening may also include a third auxiliary opening and a fourth auxiliary opening extending outward from the central opening, the third auxiliary opening and the fourth auxiliary opening including a third colinear segment and a fourth colinear segment of a second groove extending through the central opening, wherein the first groove intersects the second groove at an angle of 90°.

[0029] In some embodiments, the first dipole arm may have a substantially square outer perimeter, and the first slot and the second slot may extend along respective diagonals of the square outer perimeter.

[0030] In some embodiments, the first radiating element may be a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and the first slot may extend in the direction of the first linear polarization and the second slot may extend in the direction of the second linear polarization.

[0031] In some embodiments, the second dipole arm may include a second metal region substantially surrounding a second non-metallic interior region, and the second non-metallic interior region may be configured such that a current induced on a first portion of the second metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by RF energy emitted by the second radiating element, and the second non-metallic interior opening may include a third slot and a fourth slot in the second metal region in which metal is omitted, and a longitudinal axis of the third slot may intersect a longitudinal axis of the fourth slot at an angle of 90°.

[0032] In some embodiments, the first and third grooves may be co-linear and / or the second and fourth grooves may extend parallel to each other.

[0033] In some embodiments, each of the first to fourth dipole arms can have a substantially rectangular perimeter, except for first and second recesses on respective first and second sides of the substantially rectangular perimeter. In some embodiments, the first recess on the first dipole arm can face the first recess on the second dipole arm, and the second recess on the first dipole arm can face the second recess on the fourth dipole arm.

[0034] According to another embodiment of the present invention, an antenna is provided, the antenna comprising: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing a higher frequency than the first operating frequency band. The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm comprises a first metal sheet, the first metal sheet having a first internal opening, the first internal opening comprising a first slot and a second slot intersecting the first slot at an angle of 90°.

[0035] In some embodiments, a perimeter of the first metal sheet completely surrounds the interior opening.

[0036] In some embodiments, the first radiating element is a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and the first slot extends in the direction of the first linear polarization and the second slot extends in the direction of the second linear polarization.

[0037] In some embodiments, the second dipole arm includes a second metal sheet substantially surrounding a second internal opening, and the second internal opening is configured such that a current induced on a first portion of the second metal sheet by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal sheet by RF energy emitted by the second radiating element, the second internal opening includes a third slot and a fourth slot in the second metal region in which metal is omitted, and a longitudinal axis of the third slot intersects a longitudinal axis of the fourth slot at an angle of 90°.

[0038] In some embodiments, the first and third grooves are co-linear, and wherein the second and fourth grooves extend parallel to each other.

[0039] In some embodiments, the first internal opening includes a central opening and a plurality of satellite openings, the first groove includes a first colinear segment and a second colinear segment extending radially from the central opening, the second groove includes a third colinear segment and a fourth colinear segment extending radially from the central opening, wherein a distal end of each of the first to fourth segments terminates at a corresponding one of the satellite openings, and a width of each of the first to fourth segments is less than a width of a corresponding one of the satellite openings.

[0040] In some embodiments, the first dipole arm has a substantially square outer perimeter, and the first slot and the second slot extend along respective diagonals of the square outer perimeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a perspective view of a base station antenna according to an embodiment of the present invention.

[0042] Figure 2 The radome is removed. Figure 1 Front view of a base station antenna.

[0043] Figure 3 The radome is removed. Figure 1 Cross-sectional view of a base station antenna.

[0044] Figure 4A yes Figure 1-3 Side view of one of the low-band radiating elements of a base station antenna.

[0045] Figure 4B yes Figure 4A Front view of a dipole radiator with a low-band radiating element.

[0046] Figure 4C yes Figures 4A-4B A greatly enlarged front view of one of the dipole arms of the low-band radiating element.

[0047] Figure 5A yes Figures 4A-4B Front view of the low-band radiating element of FIG. 1 , showing the current distribution when the +45° dipole radiator is fed a low-band RF signal.

[0048] Figure 5B yes Figures 4A-4B A front view of a low-band radiating element showing the current distribution on the dipole radiator in response to radiation emitted by a -45° dipole radiator of a nearby mid-band radiating element.

[0049] Figures 6A-6G is a front view of a low-band radiating element according to another embodiment of the present invention.

[0050] Figure 7 is a schematic front view of a radiating element having dipole arms designed to mask in different frequency bands according to further embodiments of the present invention.

[0051] Figure 8 is a front view of a multi-band radiating element according to another embodiment of the present invention. DETAILED DESCRIPTION

[0052] Embodiments of the present invention generally relate to radiating elements for multi-band base station antennas, and to related base station antennas. Base station antennas including radiating elements according to embodiments of the present invention can be used, for example, as sector antennas in the above-mentioned cellular communication systems. Multi-band base station antennas according to embodiments of the present invention can support multiple major air interface standards in two or more cellular frequency bands, and allow wireless operators to reduce the number of antennas deployed at a base station, thereby reducing tower leasing costs.

[0053] A challenge in multi-band base station antenna design is to reduce the effect of scattering RF signals in one frequency band by radiating elements in other frequency bands. Scattering is undesirable because it can affect the shape of the antenna beam in both the azimuth and elevation planes, and the effect can vary significantly with frequency, which can make it difficult to compensate for these effects. In addition, at least in the azimuth plane, scattering tends to affect the beamwidth, beam shape, pointing angle, gain, and front-to-back ratio of the antenna beam in an undesirable manner. Radiating elements in accordance with embodiments of the present invention are so-called "masked" radiating elements that have a reduced effect (i.e., reduced scattering) on ​​antenna beams generated by closely positioned radiating elements that transmit and receive signals in other frequency bands.

[0054] Masking low-band radiating elements is known in the art. For example, U.S. Patent No. 9,570,804 discloses a low-band radiating element operating in the 696-960 MHz band, the low-band radiating element comprising a dipole arm formed as a series of RF chokes so as to make the low-band radiating element substantially transparent to RF energy in the 1.7-2.7 GHz band. U.S. Patent No. 10,439,285 and U.S. Patent No. 10,770,803 each disclose a low-band radiating element operating in the 696-960 MHz band, the low-band radiating element comprising a dipole arm formed as a series of widened segments connected by narrow inductor segments, which can be implemented as small serpentine trace segments on a printed circuit board. In each case, the narrow inductor segments act as high impedance elements for RF energy in the 1.7-2.7 GHz band, thereby making the low-band radiating element substantially transparent to RF energy in this frequency range. As another example, U.S. Patent No. 11,018,437 discloses a low-band radiating element operating in the 696-960 MHz band, comprising two dipole arms substantially transparent to RF energy in the 1.7-2.7 GHz band and another two dipole arms substantially transparent to RF energy in the 3.3-4.2 GHz band. Additional shielding radiation element designs are disclosed in Chinese Patent No. CN 112787061A, Chinese Patent No. CN 112164869A, Chinese Patent No. CN 112290199A, Chinese Patent No. CN 111555030A, Chinese Patent No. CN112186333A, Chinese Patent No. CN 112186341A, Chinese Patent No. CN 112768895A, Chinese Patent No. CN112821044A, Chinese Patent No. CN 213304351U, Chinese Patent No. CN 112421219A and PCT Publication WO 2021 / 042862.

[0055] According to an embodiment of the present invention, a multi-band base station antenna is provided, which includes at least an array of first radiating elements and an array of second radiating elements that transmit and receive signals in corresponding first and second (different) frequency bands. In some embodiments, the multi-band base station antenna may also include an array of third radiating elements that transmit and receive signals in a third frequency band different from the first and second frequency bands. In some embodiments, the first frequency band may include a 617-960 MHz band or a portion thereof, the second frequency band may include a 1427-2690 MHz band or a portion thereof, and the third frequency band may include a 3100-4200 MHz band or a portion thereof. Each first radiating element may be a shielded radiating element having a dipole radiator that is substantially transparent to RF energy in the second frequency band. In some embodiments, each first radiating element may also be substantially transparent to RF energy in the third frequency band.

[0056] As discussed above, many different shielded radiating elements are known in the art that are designed to be substantially transparent to RF energy emitted by nearby radiating elements operating in different frequency bands. However, many of these designs have dipole arms with integrated inductor-capacitor ("LC") resonant circuits that form filters that block current in the operating frequency band of nearby radiating elements. However, the inductors in these LC circuits can make it more difficult to impedance match the feed stem of a decoupling radiating element to its dipole arm. Shielded radiating elements according to embodiments of the present invention use frequency selective surfaces that are configured to destructively cancel RF energy in a second frequency band while passing RF energy in a first frequency band. As a result, shielded radiating elements according to embodiments of the present invention can have improved impedance matching between the feed stem and the dipole arms, which allows the radiating element to exhibit a wider operating bandwidth. In addition, shielded radiating elements according to embodiments of the present invention can provide enhanced suppression of higher frequency band currents.

[0057] The shielded radiating elements according to embodiments of the present invention may be cross-dipole radiating elements, such as -45° / +45° polarized cross-dipole radiating elements or horizontal / vertical polarized cross-dipole radiating elements. Each radiating element comprises a pair of dipole radiators radiating with orthogonal polarizations. Each dipole radiator may comprise a pair of center-fed dipole arms, such that each radiating element comprises a total of four dipole arms.

[0058] In some embodiments, each dipole arm may include a square piece of metal having an internal opening in which metal has been removed so that each dipole arm includes a metal region that substantially or completely surrounds an associated non-metallic internal region. The non-metallic internal region may include only an opening in the metal (i.e., it is air), or may be partially or completely filled with a non-metallic material. The internal openings may be shaped so that currents induced on one or more portions of the metal region by higher frequency band RF energy emitted by a nearby radiating element are substantially offset by currents induced on corresponding corresponding portions of the metal region by higher frequency band RF energy. The shape of the internal openings is also configured so that currents induced on the metal region in response to RF energy in the operating frequency band of the radiating element will flow on the dipole arm without significant offset so as to radiate the RF energy along a desired polarization direction. Thus, each dipole arm may be viewed as a frequency selective surface that allows current to flow in some frequency ranges and substantially suppresses currents in other frequency bands.

[0059] The antenna according to some embodiments of the present invention may include: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band including frequencies higher than the first operating frequency band. The first radiating element includes a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, and the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first metal region substantially surrounding a first non-metallic inner region, and the first non-metallic inner region is configured so that a current induced on a first portion of the first metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the first metal region by RF energy emitted by the second radiating element.

[0060] The antenna according to another embodiment of the present invention may include: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing a higher frequency than the first operating frequency band. The first radiating element includes a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, and the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first metal region substantially surrounding a non-metallic inner region, and the shape of the non-metallic inner region is configured to cause the first metal region to act as a frequency selective surface, the frequency selective surface conducting a current excited in response to RF energy in the first operating frequency band while counteracting a current excited in response to RF energy in the second operating frequency band.

[0061] Antennas according to some further embodiments of the present invention may include: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing higher frequencies than the first operating frequency band. The first radiating element includes a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, and the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first metal region substantially surrounding a first non-metallic inner region, the first non-metallic inner region including a central opening and first and second auxiliary openings extending outward from the central region.

[0062] An antenna according to another embodiment of the present invention may include: a reflector; a first radiating element, the first radiating element extending forward from the reflector, the first radiating element being configured to operate in a first operating frequency band; and a second radiating element, the second radiating element extending forward from the reflector, the second radiating element being configured to operate in a second operating frequency band containing a frequency higher than the first operating frequency band. The first radiating element includes a first dipole radiator and a second dipole radiator, the first dipole radiator having a first dipole arm and a second dipole arm, and the second dipole radiator having a third dipole arm and a fourth dipole arm. The first dipole arm includes a first metal sheet, the first metal sheet having an internal opening, the internal opening including a first slot and a second slot intersecting the first slot at an angle of 90°.

[0063] When an antenna according to an embodiment of the present invention includes an array of radiating elements operating in three different frequency bands, the radiating elements operating in the lowest frequency band can be referred to as "low-band" radiating elements, the radiating elements operating in the highest frequency band can be referred to as "high-band" radiating elements, and the radiating elements operating in the middle frequency band can be referred to as "mid-band" radiating elements.

[0064] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

[0065] Figure 1-3 A base station antenna 100 according to some embodiments of the present invention is shown. Specifically, Figure 1 is a perspective view of the antenna 100, and Figure 2 and Figure 3 1 and 2 are front and cross-sectional views of the antenna 100, respectively, with its radome removed to show the antenna assembly 200 of the antenna 100. In the following description, the antenna 100 and the radiating elements included therein 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 to the tower pointing to the coverage area of ​​the antenna 100.

[0066] like Figure 1-3 As shown in , the base station antenna 100 is an elongated structure extending along a longitudinal axis L. The base station antenna 100 may have a tubular shape with a generally rectangular cross-section. The antenna 100 includes a radome 110 and a top cover 120. The antenna 100 also includes a bottom cover 130, which includes a plurality of connectors 140, such as RF ports, mounted therein. When the antenna 100 is mounted for normal operation, the antenna 100 is typically mounted in a vertical configuration (i.e., the longitudinal axis L may be generally perpendicular to a plane defined by the horizon). The radome 110, the top cover 120, and the bottom cover 130 may form an outer housing of the antenna 100. The antenna assembly 200 is contained within the outer housing. The antenna assembly 200 may be slidably inserted into the radome 110 from the top or bottom before the top cover 120 or the bottom cover 130 is attached to the radome 110.

[0067] Figure 2 and Figure 3 1 and 2 are respectively a front view and a cross-sectional view of the antenna assembly 200 of the base station antenna 100. Figure 2 and Figure 3As shown in , the antenna assembly 200 includes a ground plane structure 210 having a sidewall 212 and a reflector surface 214. Various mechanical and electronic components (not shown) of the antenna, such as phase shifters, remote electronic tilt units, mechanical linkages, controllers, duplexers, etc., can be mounted in a cavity defined between the sidewall 212 and the back side of the reflector surface 214. The reflector surface 214 of the ground plane structure 210 can include or include a metal surface (e.g., an aluminum sheet) that acts as a reflector and ground plane for the radiating elements of the antenna 100. The reflector surface 214 may also be referred to herein as a reflector 214.

[0068] A plurality of dual-polarized radiating elements are mounted to extend forward from the reflector 214. The radiating elements include a low-band radiating element 224, a mid-band radiating element 234, and a high-band radiating element 244, 254. The low-band radiating element 224 is mounted in two columns to form two linear arrays 220-1, 220-2 of the low-band radiating element 224. The mid-band radiating element 234 can also be mounted in two columns to form two linear arrays 230-1, 230-2 of the mid-band radiating element 234. Two planar arrays of high-band radiating elements 244, 254 are included in the antenna 100. The first planar array 240 includes four columns 242 of high-band radiating elements 244. The second planar array 250 includes four columns 252 of high-band radiating elements 254. The high-band radiating element 244 can be the same as or different from the high-band radiating element 254. All four columns 242 high-band radiating elements 244 can be connected to the port of the first beamforming radio device (not shown) so that the first planar array 240 can perform active beamforming to generate higher gain antenna beams. All four columns 252 high-band radiating elements 254 can be connected to the port of the second beamforming radio device (not shown) so that the second planar array 250 can also perform active beamforming. In this article, the linear array 220-1, 220-2 of low-band radiating element 224 can also be referred to as low-band linear array 220-1, 220-2, the linear array 230-1, 230-2 of mid-band radiating element 234 can also be referred to as mid-band linear array 230-1, 230-2, and the array 240, 250 of high-band radiating element 244, 254 can also be referred to as high-band array 240, 250.

[0069] It will be appreciated that the number of arrays of low-band, mid-band and / or high-band radiating elements may vary. Figure 2 and 3The number of columns and / or the number of radiating elements in each array and the relative positions of the arrays may also be different than shown in FIG. It should be noted that throughout this document, the same elements may be referred to individually by their entire reference numeral (e.g., linear array 230-2) and collectively by the first portion of their reference numeral (e.g., linear array 230).

[0070] In the depicted embodiment, the first planar array and the second planar array 240, 250 of the high-band radiating elements 244, 254 are positioned between the linear arrays 220-1, 220-2 of the low-band radiating elements 224, and each linear array 220 of the low-band radiating elements 224 is positioned between the planar arrays 240, 250 of the high-band radiating elements 244, 254 and the corresponding linear arrays in the linear array 230 of the mid-band radiating elements 234. It should be understood that the antenna 100 shows a typical layout of an array of low-band radiating elements, mid-band radiating elements, and high-band radiating elements. Based on the application and customer requirements, many other array configurations are often used. For example, in another exemplary embodiment, the first planar array and the second planar array 240, 250 of the high-band radiating elements 244, 254 can be omitted or replaced with two additional mid-band linear arrays 230. The radiating elements according to embodiments of the present invention can be used in arrays with any suitable configuration.

[0071] Low-band radiating element 224 can be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may include a 617-960MHz frequency range or a portion thereof (e.g., a 617-896MHz frequency band, a 696-960MHz frequency band, etc.). Mid-band radiating element 234 can be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band may include a 1427-2690MHz frequency range or a portion thereof (e.g., a 1710-2200MHz frequency band, a 2300-2690MHz frequency band, etc.). High-band radiating elements 244, 254 can be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may include a 3300-4200MHz frequency range or a portion thereof. Two low-band linear arrays 220-1, 220-2 may be configured or may not be configured to transmit and receive signals in the same portion of the first frequency band. For example, in one embodiment, the low-band radiating elements 224 in the first linear array 220-1 can be configured to transmit and receive signals in the 700 MHz frequency band, and the low-band radiating elements 224 in the second linear array 220-2 can be configured to transmit and receive signals in the 800 MHz frequency band. In other embodiments, the low-band radiating elements 224 in both the first and second linear arrays 220-1, 220-2 can be configured to transmit and receive signals in the same frequency band to, for example, support the use of multiple-input multiple-output ("MIMO") communication technology. The mid-band radiating elements and high-band radiating elements 234, 244, 254 in the different mid-band arrays and high-band arrays 230, 240, 250 can similarly have any suitable configuration. The radiating elements 224, 234, 244, 254 can be dual-polarized radiating elements (e.g., -45° / +45° cross-dipole radiating elements or -45° / +45° polarized patch radiating elements), and therefore each array 220, 230, 240, 250 can be used to form a pair of antenna beams, i.e., the dual-polarized radiating elements are designed to transmit and receive one antenna beam for each of the two polarizations of RF signals.

[0072] Although not shown in the figure, the radiating elements 224, 234, 244, 254 can be mounted on a feeder board that couples RF signals to and from each radiating element 224, 234, 244, 254. One or more radiating elements 224, 234, 244, 254 can be mounted on each feeder board. Cables can be used to connect each feeder board to other components of the antenna, such as a duplexer, phase shifter, etc.

[0073] While cellular network operators are interested in deploying antennas with a large number of radiating element arrays in order to reduce the number of base station antennas required for each base station, increasing the number of arrays typically increases the width of the antenna. Both the weight and wind loading of a base station antenna increase with increasing width, so wider base station antennas tend to require more structurally robust antenna supports and antenna towers, both of which can significantly increase the cost of the base station. Therefore, cellular network operators may impose limits on the width of base station antennas (where the limits may depend on the application of the antenna).

[0074] The width of a multi-band base station antenna can be reduced by reducing the spacing between adjacent arrays. However, as the spacing is reduced, the interaction between the radiating elements of different arrays increases, and this increased interaction can affect the shape of the antenna beam generated by the array in an undesirable manner. For example, low-band cross-dipole radiating elements are typically dipole radiators, each of which has a length of approximately 1 / 2 wavelength of the center frequency of the designed operating band of the radiating element. Each dipole radiator typically includes a pair of center-fed dipole arms, each of which has a length of approximately 1 / 4 wavelength of the center frequency of the designed operating band of the radiating element. If, for example, the low-band radiating element is designed to operate in the 900 MHz band, and the mid-band radiating element is designed to operate in the 1800 MHz band, the length of the low-band dipole radiator will be approximately one wavelength of the mid-band operating frequency. Therefore, the length of each dipole arm of the low-band dipole radiator will be approximately 1 / 2 wavelength of the mid-band operating frequency, so the RF energy emitted by the mid-band radiating element will tend to couple into the dipole arms of the low-band radiating element because this RF energy will resonate in the 1 / 2 wavelength dipole arms.

[0075] When the intermediate frequency band and / or high frequency band RF energy is coupled to the dipole arm of the low frequency band radiating element, the corresponding intermediate frequency band and / or high frequency band current is induced on the dipole arm. When the low frequency band radiating element and the intermediate frequency band radiating element are designed to work in the frequency band with the center frequency separated by about twice (or four times), this type of induced current is particularly likely to occur, because the low frequency band dipole arm with a length of one quarter wavelength of the low frequency band operating frequency will have a length of about half wavelength (or full wavelength) of the higher frequency band operating frequency in this case. The induced current produces the intermediate frequency band (and / or high frequency band) RF radiation emitted from the low frequency band dipole arm. The intermediate frequency band / high frequency band RF energy emitted from the dipole arm of the low frequency band resonant element distorts the antenna beam of the intermediate frequency band and / or high frequency band array, because the radiation is emitted from a position different from the expected position. The greater the degree of inducing the intermediate frequency band / high frequency band current on the low frequency band dipole arm, the greater the impact on the characteristics of the antenna beam produced by the intermediate frequency band array and the high frequency band array.

[0076] The low-band radiating element 224 according to an embodiment of the present invention can be designed to be substantially transparent to the RF energy emitted by the mid-band radiating element and / or the high-band radiating element 234, 244, 254. Therefore, even if the mid-band radiating element and the high-band radiating element 234, 244, 254 are very close to the low-band radiating element 224, the undesirable coupling of the mid-band and / or high-band RF energy discussed above to the low-band radiating element 224 can be significantly reduced.

[0077] Figures 4A-4C 1 shows a low-band radiating element 300 according to an embodiment of the present invention, which can be used to implement the low-band radiating element 224 of the base station antenna 100. In particular, Figure 4A is a side view of the low-band radiating element 300, Figure 4B is a front view of the dipole radiators 320 - 1 , 320 - 2 of the low-band radiating element 300 , and Figure 4C yes Figures 4A-4B FIG. 3 is a greatly enlarged front view of the dipole arm 330 - 1 of the low-band radiating element 300 .

[0078] refer to Figure 4A , the low-band radiating element 300 includes a pair of feeding handles 310 and dipole radiators 320-1, 320-2. In some embodiments, the feeding handles 310 may each include a printed circuit board 312 having an RF transmission line 314 formed thereon. These RF transmission lines 314 transmit RF signals between a feed board (not shown) mounted on the reflector 214 and the dipole radiator 320. The feeding handles 310 extend backward from a plane defined by the dipole radiators 320-1, 320-2. For example, the feeding handles 310 may extend substantially perpendicular to the plane defined by the dipole radiators 320-1, 320-2.

[0079] Each feeding handle 310 may also include a hook balun 316. The first feeding handle 310-1 in the feeding handle may include a front slit, and the second feeding handle 310-2 in the feeding handle includes a rear slit. These slits allow the two feeding handles 310 to be assembled together to form a forward extending column having a generally x-shaped vertical cross-section. The rear portion of each feeding handle 310 may include a protrusion that is inserted through a slit in a feed plate (not shown) to mount the radiating element 300 thereon. The RF transmission line 314 on the corresponding feeding handle 310 can center feed the dipole radiators 320-1 and 320-2. Although the feeding handle 310 is shown as a feeding handle based on a printed circuit board, it should be understood that embodiments of the present invention are not limited thereto. In other embodiments, a sheet metal feed stem may instead be used (eg, in the form of four rearwardly extending dipole legs, which may be used in conjunction with a pair of sheet metal hook baluns to form feed stem 310).

[0080] In some embodiments, the first and second dipole radiators 320-1 and 320-2 may include metal sheet dipole radiators. The first dipole radiator 320-1 includes a first dipole arm and a second dipole arm 330-1 and 330-2, and the second dipole radiator 320-2 includes a third dipole arm and a fourth dipole arm 330-3 and 330-4. Figure 4B As shown in FIG. , the dipole radiators 320-1, 320-2 may be implemented in a "cross" arrangement to form a pair of center-fed -45° / +45° dipole radiators 320. In some embodiments, each dipole arm 330 may include a separate piece of stamped metal. Figure 4B A sheet metal dipole arm 330 is shown in FIG. 3 , but it will be appreciated that in other embodiments, the two dipole radiators 320 - 1 , 320 - 2 (and their constituent dipole arms 330 ) may alternatively be formed on a dipole radiator printed circuit board.

[0081] The azimuth half-power beamwidth of each low-band radiating element 300 may be in the range of 55° to 85°. In some embodiments, the azimuth half-power beamwidth of each low-band radiating element 300 may be approximately 65° at the center of the operating frequency band of the low-band radiating element 300.

[0082] The length of each dipole arm 330 can be between approximately 0.2 and 0.35 operating wavelengths, where "operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of the radiating element 300. For example, if the low-band radiating element 300 is designed to transmit and receive signals across the 694-960 MHz band, the center frequency of the operating frequency band will be 827 MHz, and the corresponding operating wavelength will be 36.25 cm. As used herein, the "length" of a dipole arm refers to the span of the dipole arm from its base (which is typically the portion of the dipole arm that connects to the feed handle) to its distal end. For the dipole arms 330, the length of each dipole arm is the length of the diagonal of the square defined by the outer perimeter of each dipole arm 330.

[0083] The dipole radiator 320-1 may include a first stamped metal sheet and a second stamped metal sheet 322-1, 322-2 forming dipole arms 330-1, 330-2. The dipole radiator 320-2 may similarly include a third stamped metal sheet and a fourth stamped metal sheet 322-3, 322-4 forming dipole arms 330-3, 330-4. As shown, the four dipole arms 330 may be arranged to form a rectangle 324 (typically a square 324). The dipole arms 330-1, 330-2 extend along one diagonal of the square 324, while the dipole arms 330-3, 330-4 extend along another diagonal of the square 324. In some embodiments, the four dipole arms 330 may extend in a common plane parallel to the reflector 214. Each feeding stem 310 may extend in a direction generally perpendicular to a plane defined by the dipole arms 330 such that the feeding stem 310 extends in a forward direction.

[0084] like Figure 4B As best shown in FIG. 1 , a first dipole radiator 320-1 extends along a first axis 326-1 and a second dipole radiator 320-2 extends along a second axis 326-2 that is substantially perpendicular to the first axis 326-1. Dipole arms 330-1 and 330-2 of the first dipole radiator 320-1 are center-fed by a first of the RF transmission lines 314 and radiate together at a first polarization. In the depicted embodiment, the first dipole radiator 320-1 is designed to transmit and receive signals having a +45° polarization. Dipole arms 330-3 and 330-4 of the second dipole radiator 320-2 are center-fed by a second of the RF transmission lines 314 and radiate together at a second polarization that is orthogonal to the first polarization. The second dipole radiator 320-2 is designed to transmit and receive signals having a -45° polarization. The dipole arm 330 may be mounted via the feed handle 310 in front of the reflector 214 at approximately 3 / 16 to 1 / 4 of the operating wavelength.

[0085] Reference again Figure 2 and Figure 3 , it can be seen that the low-band radiating element 224 (300) extends further forward from the reflector 214 than both the mid-band radiating element 234 and the high-band radiating elements 244, 254. In order to keep the width of the base station antenna 100 relatively narrow, the low-band radiating element 224 (300) can be positioned very close to both the mid-band radiating element 234 and the high-band radiating elements 244, 254. In the depicted embodiment, each low-band radiating element 224 (300) of the linear array 230 adjacent to the mid-band radiating element 234 can overlap a majority of two of the mid-band radiating elements 234. Similarly, each low-band radiating element 224 (300) of the array 240, 250 adjacent to the high-band radiating elements 244, 254 can overlap at least a portion of one or more of the high-band radiating elements 244, 254. This arrangement allows the width of the base station antenna 100 to be significantly reduced. As used herein, two radiating elements "overlap" if an axis perpendicular to a plane defined by the reflector to which the radiating elements are mounted passes through the two radiating elements.

[0086] Although positioning the low-band radiating elements 224 (300) so that they overlap with the mid-band radiating elements and / or the high-band radiating elements 234, 244, 254 can advantageously facilitate reducing the width of the base station antenna 100, this approach may significantly increase the coupling of RF energy emitted by the mid-band radiating elements and / or the high-band radiating elements 234, 244, 254 to the low-band radiating elements 224 (300), and such coupling may result in scattering of the antenna beam formed by the arrays 230, 240, 250 of the mid-band radiating elements and / or the high-band radiating elements 234, 244, 254.

[0087] To reduce this coupling, the low-band radiating element 300 can be designed with a dipole arm 330 that is substantially "transparent" to radiation emitted by either or both of the mid-band radiating element 234 and the high-band radiating elements 244, 254. This can be challenging because the mid-band radiating element 234 can (in some cases) operate at frequencies as low as 1427 MHz, and the high-band radiating elements 244, 254 can (in some cases) operate at frequencies as high as 4200 MHz. Therefore, ideally, the low-band radiating element 300 is substantially transparent to RF energy in the frequency range of 1427-4200 MHz, while allowing current in the frequency range of 617-960 MHz to flow freely on the dipole arm 330. In this article, a dipole arm of a radiating element configured to transmit RF energy in a first frequency band is considered to be "transparent" to RF energy in a second different frequency band if RF energy in a second different frequency band is poorly coupled to the dipole arm. Thus, if the dipole arm of a first radiating element transparent to the second frequency band is positioned such that it overlaps a second radiating element emitting in the second frequency band, adding the first radiating element will not substantially affect the antenna pattern of the second radiating element.

[0088] Figure 4C is a greatly enlarged front view of dipole arm 330-1. Figure 4C , a piece of metal sheet used to form the first dipole arm 330-1 is stamped to create an opening in a central region thereof. Thus, the first dipole arm 330-1 includes a first metal region 332-1 that substantially surrounds a first non-metallic interior region 334-1. In the depicted embodiment, the first metal region 332-1 completely surrounds the first non-metallic interior region 334-1. In some embodiments, the outer perimeter of the first metal region 332-1 can be substantially rectangular. In the depicted embodiment, the outer perimeter of the first metal region 332-1 is substantially square, having first to fourth side edges 336-1 to 336-4.

[0089] The outer perimeter of the first metal region 332-1 is only "substantially" square because the first and second recesses 338-1, 338-2 are formed in the outer portions of the first and second sides of the first metal region 332-1. In the depicted embodiment, the first and second recesses 338-1, 338-2 each have a rectangular shape and are approximately centered in the middle along the respective first and second sides of the first metal region 332-1. Each dipole arm 330 includes a first and second recess 338-1, 338-2, which are arranged so that the first recess 338-1 on each dipole arm 330 faces the second recess 338-2 on the adjacent dipole arm 330. The recess 338 can reduce the undesirable coupling between the first dipole radiator and the second dipole radiator 320-1, 320-2, which can improve the cross-polarization discrimination performance of the low-band linear array 220. It should be appreciated that in other embodiments, more than one recess 338 may be provided on each side edge 336, recesses 338 may be provided on the outer edges 336-3, 336-4, recesses 338 may be omitted, and / or the size and / or shape of recesses 338 may differ from that shown.

[0090] In some embodiments, the first metal region 332-1 may be a substantially flat piece of metal in which an opening is formed. The first metal region 332-1 may be formed by stamping a piece of metal sheet to remove the metal corresponding to the opening. In some embodiments, the first metal region 332-1 may completely surround the opening to enclose the opening. The first metal region 332-1 may have an outer periphery that substantially defines a square. The first metal region 332-1 may include, for example, aluminum, steel, or copper or an alloy thereof. In other embodiments, the first metal region 332-1 may not be flat. For example, the outer edge of the first metal region 332-1 may be bent backward (or forward) to increase the size of the dipole arm 330-1 without increasing its occupied area (the occupied area of ​​the dipole arm refers to the periphery of the dipole arm when viewed from the front). In addition or alternatively, for the same purpose, the edge of the internal opening may be bent backward (or forward). In such embodiments, the metal corresponding to the opening may not be completely removed, but the portion of the metal corresponding to the opening is bent backward.

[0091] The first non-metallic inner region 334-1 includes a central opening 340-1 and a first auxiliary opening to a fourth auxiliary opening 342-1, 344-1, 346-1, 348-1 extending outward from the central opening 340-1. In the depicted embodiment, the central opening 340-1 has a square shape, and the first auxiliary opening to the fourth auxiliary opening 342-1, 344-1, 346-1, 348-1 extend radially outward from the central opening 340-1. The first auxiliary opening and the second auxiliary opening 342-1, 344-1 include a first collinear segment and a second collinear segment of the first slot 360-1 extending through the central opening 340-1. The third auxiliary opening and the fourth auxiliary opening 346-1, 348-1 include a third collinear segment and a fourth collinear segment of the second slot 362-1 extending through the central opening 340-1. The longitudinal axis of the first slot 360-1 intersects the longitudinal axis of the second slot 362-1 at an angle of 90°. The first slot 360-1 extends at an angle of -45° and thus extends along the polarization direction of the first dipole radiator 320-1. The second slot 362-1 extends at an angle of +45° and thus extends along the polarization direction of the second dipole radiator 320-2. When the first and second slots 360, 362 are aligned along the respective polarization directions, the current distribution on the dipole arm 330 can be more easily controlled. As described above, in some embodiments, the outer perimeter of the first metal region 332-1 can be substantially square. In such embodiments, the longitudinal axes of the first and second slots 360-1, 362-1 can extend along respective diagonals defined by the substantially square outer perimeter of the first metal region 332-1.

[0092] The plurality of auxiliary openings may also include a plurality of satellite openings 350-1, 352-1, 354-1, 356-1. In the depicted embodiment, each satellite opening 350-1, 352-1, 354-1, 356-1 has a square shape and merges into the distal end of a respective one of the first to fourth segments of the first and second slots 360-1, 362-1. In other words, the distal ends of the first to fourth segments terminate in the respective square satellite openings 350-1, 352-1, 354-1, 356-1. The longitudinal axis of the first slot 360-1 may be aligned with one of the diagonals of the square satellite openings 350-1, 352-1, and the longitudinal axis of the second slot 362-1 may be aligned with one of the diagonals of the square satellite openings 354-1, 356-1. The first segment and the second segment of the first slot 360-1 each have a width W1. The width W2 of each of the first and second satellite openings 350-1, 352-1 (wherein the widths W1 and W2 refer to the span of the segment / satellite opening in the plane defined by the dipole radiators 320-1, 320-2 in a direction perpendicular to the longitudinal axis of the first slot 360-1) can be greater than the width W1 of the first and second segments. Therefore, the first and second satellite openings 350-1, 352-1 expand the distal ends of the first and second segments of the first slot 360-1.

[0093] Each of the second through fourth dipole arms 330-2 through 330-4 may have the same exact shape as the first dipole arm 330-1 (although each dipole arm 330 is oriented differently than the other dipole arms 330, such as Figure 4B ). Thus, for example, the second dipole arm 330-2 includes a second metal region 332-2 that substantially surrounds the second non-metallic interior region 334-2. The second non-metallic interior region 334-2 includes a first slot and a second slot 360-2, 362-2. The longitudinal axis of the first slot 360-2 intersects the longitudinal axis of the second slot 362-2 at an angle of 90°. Notably, the first slot 360-1 of the first dipole arm 330-1 is collinear with the first slot 360-2 of the second dipole arm 330-2. The second slot 362-1 of the first dipole arm 330-1 extends parallel to (but not collinear with) the second slot 362-2 of the second dipole arm 330-2.

[0094] Each dipole arm 330 may be configured to inhibit current from forming thereon in response to RF radiation emitted by the mid-band radiating element 234 and / or the high-band radiating element 244, 254, which may be located proximate to the low-band radiating element 300. Specifically, each dipole arm 330 may be configured such that the instantaneous direction of a first current formed on a first portion of the dipole arm 330 in response to RF radiation emitted by the mid-band radiating element or the high-band radiating element 234, 244, 254 will be substantially opposite to the instantaneous direction of a second current formed on a second portion of the dipole arm 330 in response to the mid-band or high-band RF radiation. Thus, the first and second currents "flowing" on the dipole arm 330 will tend to cancel each other, thereby inhibiting current from forming on the low-band dipole arm 330 in response to RF radiation emitted by the nearby mid-band radiating element and / or the high-band radiating element 234, 244, 254. This can be achieved by shaping the first non-metallic interior region 334-1 so that the first metal region 332-1 acts as a frequency selective surface that conducts currents excited in response to RF energy in the first operating frequency band while canceling currents excited in response to RF energy in the second operating frequency band. In contrast, the currents induced in the dipole arms 330 in response to RF energy in the low-band frequency range have the same current direction, so that the dipole arms will effectively transmit and receive in the low-band.

[0095] Figure 5A and Figure 5B is a front view of the radiating element 300 showing simulated current density on its dipole arms 330 in response to RF energy in the low-band operating band and the high-band operating band, respectively. Figure 5A and Figure 5B , the triangles illustrate the current induced on the dipole arm 330, wherein the vertex of each triangle represents the current direction, and the size of each triangle indicates the density of the current (wherein a larger triangle represents a larger current density). Figure 5A The dashed horizontal and vertical vectors in show the general direction of the current on the dipole arm 330 in response to the low-band RF energy.

[0096] like Figure 5AAs shown in , when the +45° dipole radiator 320-1 of the radiating element 300 is fed with low-band RF energy, low-band currents are induced primarily on the dipole arms 330-1 and 330-2, with much smaller currents induced on the dipole arms 330-3 and 330-4 due to the incomplete differentiation between the two dipole radiators 320-1, 320-2. As shown by the dashed vectors, on the dipole arm 330-2, the current flows from the distal end toward the base, and on the dipole arm 330-1, the current flows from the base toward the distal end. The strongest currents on each dipole arm 330 flow along the two inner edges 336-1, 336-2 of each dipole arm 330, flowing in the horizontal direction on one of the inner edges and in the vertical direction on the other inner edge. The magnitudes of these currents are substantially equal and together produce RF radiation having a +45° polarization, as is well understood by those skilled in the art. therefore, Figure 5A It is shown that radiating element 300 will efficiently radiate low-band RF energy with a desired polarization.

[0097] Figure 5B 3 shows the current distribution on the dipole arm 330 when a nearby higher frequency band radiating element is emitting RF energy. Figure 5B In FIG. 3 , the nearby higher frequency band radiating element emits RF radiation having a -45° polarization, so it can be seen that the higher frequency band current induced on the dipole arm 330 is induced along the edge of the second slot 362 extending at a -45° angle and extends around the satellite openings 354, 356 of the second slot 362. Figure 5B As shown in , these higher frequency band currents are generated along both sides of the second slot 362. Therefore, the current flowing on one side of a given second slot 362 tends to be equal and opposite to the current flowing on the other side of the second slot 362. The same is true with respect to the current flowing around the satellite openings 354, 356. The net result is that the higher frequency band currents tend to cancel each other out, leaving very little net higher frequency band current on the dipole arm 330. As shown in FIG. Figure 5B 300, the amount of higher frequency band current on other portions of the dipole arm 330 is very low. Thus, the dipole arm 330 tends to be substantially invisible to the higher frequency band current, such that only very low levels of higher frequency band current are effectively induced on the dipole arm 330. As a result, the radiating element 300 will not substantially affect the radiation pattern of nearby higher frequency band radiating elements, including higher frequency band radiating elements mounted directly behind the radiating element 300.

[0098] As made clear in the discussion above, radiating element 300 suppresses the generation of higher frequency band currents by configuring the non-metallic interior region 334 of each dipole arm 330 so that the current induced in the first portion of the metal region 332 of the dipole arm 330 by the RF energy emitted by the nearby second radiating element substantially cancels the current induced in the second portion of the metal region 332 by the RF energy emitted by the nearby second radiating element.

[0099] It should be understood that many modifications may be made to radiating element 300 and it will still provide the same shielding performance, so long as the non-metallic interior region 334 of each dipole arm 330 is configured such that the current induced on the first portion of the metallic region 332 by the RF energy emitted by a nearby higher frequency band second radiating element substantially cancels the current induced on the second portion of the metallic region 332 by the RF energy emitted by the nearby second radiating element. Figures 6A-6G Additional exemplary radiating elements that can provide the same type of shielding performance are shown. In each figure, only the upper left dipole arm of the radiating element is shown to simplify the drawings. It should be understood that Figures 6A-6G The radiating elements shown in FIG. 1 will each have Figure 4B The four dipole arms are arranged in the manner shown in FIG.

[0100] refer to Fig. 6A , shows a dipole arm 430 of a radiating element according to another embodiment of the present invention. The dipole arm 430 is similar to Figure 4C 4. Dipole arm 430 is similar to dipole arm 330-1, except that satellite openings 450, 452, 454, 456 of non-metallic interior region 434 of dipole arm 430 are each rotated 45° relative to satellite openings 350, 352, 354, 356 of non-metallic interior region 334-1 of dipole arm 330-1. Since all other aspects of dipole arm 430 may be the same as dipole arm 330-1, further description of dipole arm 430 or its operation will be omitted.

[0101] refer to Figure 6B The dipole arm 530 of the radiation element according to another embodiment of the present invention is also similar to Figure 4C 330-1, except that the satellite openings 550, 552, 554, 556 of the non-metallic inner region 534 of the dipole arm 530 each have a circular shape, rather than the square satellite openings 350, 352, 354, 356 as in the case of the dipole arm 330-1. Since all other aspects of the dipole arm 530 can be the same as the dipole arm 330-1, further description of the dipole arm 530 or its operation will be omitted. It should be understood that according to other embodiments of the present invention, the satellite openings in the dipole arm can have a variety of different shapes, such as hexagonal, octagonal, etc.

[0102] refer to Figure 6C The dipole arm 630 of the radiation element according to another embodiment of the present invention is also similar to Figure 4C 630, except that the square center opening 640 of the non-metallic interior region 634 of the dipole arm 630 is rotated 45° relative to the square center opening 340-1 of the dipole arm 330-1. Since all other aspects of the dipole arm 630 may be the same as the dipole arm 330-1, further description of the dipole arm 630 or its operation will be omitted.

[0103] refer to Fig.6D , shows a dipole arm 730 of a radiating element according to another embodiment of the present invention, which is similar to Figure 4C 330-1, except that the central opening 740 of the non-metallic inner region 734 of the dipole arm 730 has a circular shape, rather than a square central opening 340 as in the case of the dipole arm 330-1. Since all other aspects of the dipole arm 730 may be the same as the dipole arm 730-1, further description of the dipole arm 730 or its operation will be omitted. It should be understood that in the dipole arms according to other embodiments of the present invention, the central opening may have a variety of different shapes, such as hexagonal, octagonal, etc.

[0104] refer to Fig. 6E , shows a dipole arm 830 of a radiation element according to another embodiment of the present invention, which is also similar to Figure 4C Dipole arm 830 is identical to dipole arm 330-1, except that its non-metallic interior region 834 further includes a third horizontally oriented slot 864 and a fourth vertically oriented slot 866 that each extend through a square center opening 840 of the non-metallic interior region 834. The non-metallic interior region 834 also includes four additional satellite openings 851, 853, 855, 857 formed at the ends of the third and fourth slots 864, 866.

[0105] refer to Fig. 6F , shows a dipole arm 930 of a radiation element according to another embodiment of the present invention, which is also similar to Fig. 6E The dipole arm 930 is different from the dipole arm 830 in that the first and second slots 360, 362 are omitted, and the first to fourth satellite openings 350, 352, 354, 356 are also omitted. A radiating element having the design of the dipole arm 930 may be particularly useful when implementing a cross-dipole radiating element that transmits and receives signals with horizontal polarization and vertical polarization.

[0106] refer to Figure 6G, shows a dipole arm 1030 of a radiating element according to another embodiment of the present invention. The dipole arm 1030 is similar to Figure 4C 1, except that the satellite openings 1050, 1052, 1054, 1056 of the non-metallic inner region 1034 of the dipole arm 1030 are formed as squares with a recess 1070 formed therein. Since all other aspects of the dipole arm 1030 may be the same as the dipole arm 330-1, further description of the dipole arm 1030 or its operation will be omitted.

[0107] Simulations indicate that radiating elements according to embodiments of the present invention can provide good performance in lower frequency bands while also providing good masking performance relative to nearby higher frequency band radiating elements. In some exemplary embodiments, radiating elements according to embodiments of the present invention can be implemented as low-band radiating elements that work in all parts of the 617-960MHz frequency band, and can be designed to mask, for example, RF energy in the 2.5-2.7GHz frequency band and / or 3.3-3.8GHz frequency band. However, it should be understood that these are merely examples, and radiating elements according to embodiments of the present invention can be designed to work in different other frequency bands different from those discussed above and / or provide masking in different frequency bands. For example, in other embodiments, radiating elements can be designed to work in all or part of the 1.695-2.690GHz frequency band, and can be designed to mask, for example, RF energy in the 3.3-3.8GHz frequency band.

[0108] For example, Figure 8 1 is a front view of a mid-band radiating element 1200 according to another embodiment of the present invention, which is shielded relative to nearby high-band radiating elements. The mid-band radiating element 1200 can be designed to operate in the 1.695-2.690 GHz band, for example, and can be designed to be shielded relative to nearby radiating elements operating in the 3.3-3.7 GHz band. The mid-band radiating element 1200 includes a first dipole radiator 1220-1 and a second dipole radiator 1220-2, the first dipole radiator including dipole arms 1230-1 and 1230-2, and the second dipole radiator including dipole arms 1230-3 and 1230-4. Each dipole arm includes a metal region 1232 surrounding a non-metallic internal region 1234. Since the mid-band radiating element 1200 operates in the same manner as other radiating elements according to embodiments of the present invention described above, further description thereof is omitted herein.

[0109] As discussed above, the radiating element according to an embodiment of the present invention is formed using a dipole arm having a metal region surrounding a non-metallic inner region. The shape of the non-metallic inner region can be designed so that the dipole arm operates as a "normal" dipole arm in the operating frequency band of the dipole arm, thereby allowing the current in this band to flow freely without being cancelled, while the shape of the non-metallic inner region is also designed so that the current induced on the first part of the metal region of the dipole arm in response to the higher frequency band RF energy emitted by the nearby radiating element substantially cancels the current induced on the second part of the metal region by the RF energy emitted by the nearby radiating element. In order to have this characteristic, the non-metallic inner region can have a plurality of sections that together define a ring structure. The higher frequency band current is a differential mode current induced by RF radiation from the nearby higher frequency band radiating element. These higher frequency band currents flow on the metal regions of the various sections surrounding the non-metallic inner region. The various sections of the non-metallic inner region are designed so that the higher frequency band current flows in different directions when flowing around each section, so as to achieve a cancellation effect. In contrast, since the lower frequency band energy is excited by the feeding handle so that the low frequency band current has the same direction as the non-metallic inner region (eg, inclined at 45°), the lower frequency band current does not cancel.

[0110] Figure 7 is a schematic front view of a radiating element 1100 according to another embodiment of the present invention, the radiating element having a dipole arm 1130 designed to mask in different frequency bands. Figure 7 As shown in , the radiating element 1100 can be installed in the base station antenna to overlap with two mid-band radiating elements 234 and overlap with several high-band radiating elements 244. The dipole arms 1130-2 and 1130-3 overlap with the mid-band radiating elements 234, while the dipole arms 1130-1 and 1130-4 overlap with the high-band radiating elements 244. Therefore, the non-metallic internal openings 1134-2, 1134-3 of the dipole arms 1130-2 and 1130-3 can have a first shape designed to suppress mid-band currents, while the non-metallic internal openings 1134-1, 1134-4 of the dipole arms 1130-1 and 1130-4 can have a second different shape designed to suppress high-band currents. Therefore, the dipole arm 1130 of each dipole radiator of the radiating element 1100 can be unbalanced so that the portion of the radiating element 1100 overlapping with the mid-band radiating element 234 provides good shielding with respect to the mid-band currents, and the portion of the radiating element 1100 overlapping with the high-band radiating element 244 provides good shielding with respect to the high-band currents.

[0111] Radiating elements according to embodiments of the present invention may provide a number of advantages. As described above, the dipole arms achieve shielding without the use of an LC circuit, so they do not have the large inductance values ​​present in many conventional dipole arms, which can make it difficult to impedance match the dipole arms to the feed stem. Therefore, shielded radiating elements according to embodiments of the present invention may support a greater operating bandwidth than many conventional shielded radiating elements. In addition, since each dipole arm of a radiating element according to embodiments of the present invention may be formed from a single, continuous piece of metal, the dipole arms may be easily formed by simply stamping a sheet of metal, which may significantly reduce the cost of the radiating element.

[0112] Although the dipole arms of the low-band radiating element described above are implemented using stamped metal sheets, it should be understood that embodiments of the present invention are not limited thereto. For example, in other embodiments, all four dipole arms may be implemented on a dipole radiator printed circuit board.

[0113] Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be interpreted as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and these embodiments will fully convey the scope of the present invention to those skilled in the art. Throughout the text, the same reference numerals represent the same elements.

[0114] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0115] It will be understood that when an element is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element. Conversely, when an element is described as being "directly on" another element, there are no intermediate elements. It will also be understood that when an element is described as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or there may be an intermediate element. Conversely, when an element is described as being "directly connected" or "directly coupled" to another element, there are no intermediate elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.).

[0116] 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 is to be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the accompanying drawings.

[0117] In this context, the term "substantially" means within + / - 10%.

[0118] The terms used in this article are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include plural forms unless the context clearly indicates otherwise. It will also be understood that the terms "including", "comprising" and / or "having" when used in this article refer to the presence of the described features, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, operations, elements, parts and / or their groupings.

[0119] Aspects and elements of all of the embodiments disclosed above may be combined in any manner and / or combined with aspects or elements of other embodiments to provide multiple additional embodiments.

Claims

1. An antenna, comprising: Reflector; a first radiating element extending forwardly from the reflector, the first radiating element being configured to operate in a first operating frequency band; as well as a second radiating element extending forwardly from the reflector, the second radiating element being configured to operate in a second operating frequency band including higher frequencies than the first operating frequency band; The first radiating element includes a first dipole radiator and a second dipole radiator, the first dipole radiator has a first dipole arm and a second dipole arm, and the second dipole radiator has a third dipole arm and a fourth dipole arm, wherein the first dipole arm includes a first metallic region substantially surrounding a first non-metallic interior region, and the first non-metallic interior region is configured such that a current induced in a first portion of the first metallic region by radio frequency ("RF") energy emitted by the second radiating element substantially cancels a current induced in a second portion of the first metallic region by RF energy emitted by the second radiating element. 2 . The antenna of claim 1 , wherein the first metallic region comprises a closed loop that completely surrounds the first non-metallic interior region.

3. The antenna according to claim 1 or 2, wherein the first non-metallic internal region includes a first groove and a second groove in which metal is omitted in the first metal region, and wherein the longitudinal axis of the first groove intersects the longitudinal axis of the second groove at an angle of 90°.

4. The antenna of claim 3, wherein the first radiating element is a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and wherein the first slot extends in the direction of the first linear polarization and the second slot extends in the direction of the second linear polarization.

5. The antenna of claim 3, wherein the second dipole arm comprises a second metal region substantially surrounding a second non-metallic interior region, and the second non-metallic interior region is configured such that a current induced on a first portion of the second metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by RF energy emitted by the second radiating element, and wherein the second non-metallic interior opening comprises a third slot and a fourth slot in the second metal region from which metal is omitted, and wherein a longitudinal axis of the third slot intersects a longitudinal axis of the fourth slot at an angle of 90°. The antenna of claim 5 , wherein the first slot and the third slot are collinear. The antenna according to claim 6 , wherein the second slot and the fourth slot extend parallel to each other.

8. The antenna according to any one of claims 1-7, wherein the first non-metallic inner region comprises a central opening and a first auxiliary opening and a second auxiliary opening extending outwardly from the central opening.

9. The antenna of claim 8, wherein the first auxiliary opening and the second auxiliary opening comprise first and second co-linear segments of a first slot extending through the central opening.

10. The antenna of claim 9, wherein the central opening further comprises a third auxiliary opening and a fourth auxiliary opening extending outward from the central region, the third auxiliary opening and the fourth auxiliary opening comprising a third co-linear segment and a fourth co-linear segment extending through the second slot of the central opening. The antenna according to claim 10 , wherein the first slot intersects the second slot at an angle of 90°.

12. The antenna of claim 3, wherein the first dipole arm has a square outer perimeter, and the first slot and the second slot extend along respective diagonals of the square outer perimeter.

13. The antenna of any one of claims 1-12, wherein the first non-metallic interior region comprises a central opening and a plurality of auxiliary openings extending radially outward from the central opening.

14. The antenna according to claim 13, wherein the plurality of auxiliary openings include a first slot and a second slot, the first slot includes a first segment and a second segment that are collinear and extend radially from the central opening, and the second slot includes a third segment and a fourth segment that are collinear and extend radially from the central opening. The antenna of claim 14 , wherein the first to fourth segments define a cross shape.

16. The antenna of claim 14, wherein the plurality of auxiliary openings further comprises a plurality of satellite openings, wherein a distal end of each of the first to fourth segments terminates at a corresponding one of the satellite openings, and wherein a width of each of the first to fourth segments is smaller than a width of a corresponding one of the satellite openings.

17. The antenna of claim 16, wherein each satellite opening is a rectangular opening.

18. The antenna of any one of claims 1 or 2, wherein the first metallic region comprises a piece of metal sheet, and the first non-metallic interior region comprises an opening punched into the piece of metal sheet.

19. The antenna of any one of claims 1-17, wherein each of the first to fourth dipole arms has a substantially rectangular perimeter except for first and second recesses on respective first and second sides of the substantially rectangular perimeter.

20. The antenna of claim 19, wherein the first recess on the first dipole arm faces the first recess on the second dipole arm, and the second recess on the first dipole arm faces the second recess on the fourth dipole arm.

21. The antenna of claim 13, wherein the first to fourth dipole arms each have a base adjacent to a feed structure of the first radiating element and a distal end opposite the base.

22. The antenna of claim 21, wherein the first radiating element further comprises at least one feed stem extending generally perpendicular to a plane defined by the radially extending slot.

23. The antenna of any one of claims 1-22, wherein the first to fourth dipole arms are configured to be substantially transparent to RF signals in the second operating frequency band.

24. An antenna according to any one of claims 1-23, wherein the shape of the first non-metallic internal region is configured to cause the first metal region to act as a frequency selective surface, which conducts current excited in response to RF energy in the first operating frequency band while counteracting current excited in response to RF energy in the second operating frequency band.

25. An antenna, comprising: Reflector; a first radiating element extending forwardly from the reflector, the first radiating element being configured to operate in a first operating frequency band; as well as a second radiating element extending forwardly from the reflector, the second radiating element being configured to operate in a second operating frequency band including higher frequencies than the first operating frequency band; The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator has a first dipole arm and a second dipole arm, the second dipole radiator has a third dipole arm and a fourth dipole arm, and wherein the first dipole arm includes a first metallic region substantially surrounding a non-metallic inner region, and a shape of the non-metallic inner region is configured such that the first metallic region acts as a frequency selective surface that conducts current excited in response to RF energy in the first operating frequency band while counteracting current excited in response to RF energy in the second operating frequency band.

26. The antenna of claim 25, wherein the first metallic region comprises a closed loop completely surrounding the first non-metallic interior region.

27. The antenna of claim 25, wherein the first non-metallic interior region comprises a first slot and a second slot in the first metal region where metal is omitted, and wherein a longitudinal axis of the first slot intersects a longitudinal axis of the second slot at an angle of 90°.

28. The antenna of claim 27, wherein the first radiating element is a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and wherein the first slot extends in the direction of the first linear polarization and the second slot extends in the direction of the second linear polarization.

29. The antenna of claim 27, wherein the second dipole arm comprises a second metal region substantially surrounding a second non-metallic interior region, and the second non-metallic interior region is configured such that a current induced on a first portion of the second metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by RF energy emitted by the second radiating element, wherein the second non-metallic interior opening comprises a third slot and a fourth slot in the second metal region from which metal is omitted, and wherein a longitudinal axis of the third slot intersects a longitudinal axis of the fourth slot at an angle of 90°.

30. The antenna of claim 29, wherein the first slot and the third slot are co-linear, and the second slot and the fourth slot extend parallel to each other.

31. The antenna of any one of claims 25-30, wherein the first non-metallic interior region comprises a central opening and a plurality of auxiliary openings extending radially outward from the central opening.

32. The antenna according to claim 31, wherein the plurality of auxiliary openings include a first slot and a second slot, the first slot including a first segment and a second segment that are collinear and extend radially from the central opening, and the second slot including a third segment and a fourth segment that are collinear and extend radially from the central opening.

33. The antenna of claim 32, wherein the first to fourth segments define a cross shape.

34. The antenna of claim 32, wherein the plurality of auxiliary openings further comprises a plurality of satellite openings, wherein a distal end of each of the first to fourth segments terminates at a corresponding one of the satellite openings, and wherein a width of each of the first to fourth segments is smaller than a width of a corresponding one of the satellite openings.

35. The antenna of claim 34, wherein each satellite opening is a rectangular opening.

36. The antenna of any one of claims 25-35, wherein each of the first to fourth dipole arms has a substantially rectangular perimeter except for first and second recesses on respective first and second sides of the substantially rectangular perimeter.

37. The antenna of claim 36, wherein the first recess on the first dipole arm faces the first recess on the second dipole arm, and the second recess on the first dipole arm faces the second recess on the fourth dipole arm.

38. An antenna comprising: Reflector; a first radiating element extending forwardly from the reflector, the first radiating element being configured to operate in a first operating frequency band; as well as a second radiating element extending forwardly from the reflector, the second radiating element being configured to operate in a second operating frequency band including higher frequencies than the first operating frequency band; The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator has a first dipole arm and a second dipole arm, the second dipole radiator has a third dipole arm and a fourth dipole arm, and The first dipole arm includes a first metal region substantially surrounding a first non-metallic inner region, the first non-metallic inner region includes a central opening and first and second auxiliary openings radially extending from the central opening.

39. The antenna of claim 38, wherein the first metallic region comprises a closed loop that completely surrounds the first non-metallic interior region.

40. The antenna of claim 39, wherein the first auxiliary opening and the second auxiliary opening comprise first and second co-linear segments of a first slot extending through the central opening.

41. An antenna according to claim 40, wherein the central opening further includes a third auxiliary opening and a fourth auxiliary opening extending outward from the central opening, the third auxiliary opening and the fourth auxiliary opening comprising a third colinear segment and a fourth colinear segment of a second slot extending through the central opening, wherein the first slot intersects the second slot at an angle of 90°.

42. The antenna of claim 41, wherein the first dipole arm has a substantially square outer perimeter, and the first slot and the second slot extend along respective diagonals of the square outer perimeter.

43. The antenna of claim 42, wherein the first radiating element is a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and wherein the first slot extends in the direction of the first linear polarization and the second slot extends in the direction of the second linear polarization.

44. An antenna according to claim 43, wherein the second dipole arm includes a second metal region substantially surrounding a second non-metallic internal region, and the second non-metallic internal region is configured so that a current induced on a first portion of the second metal region by RF energy emitted by the second radiating element substantially cancels a current induced on a second portion of the second metal region by RF energy emitted by the second radiating element, and wherein the second non-metallic internal opening includes a third slot and a fourth slot in the second metal region in which metal is omitted, and wherein a longitudinal axis of the third slot intersects a longitudinal axis of the fourth slot at an angle of 90°.

45. The antenna of claim 44, wherein the first slot and the third slot are co-linear, and wherein the second slot and the fourth slot extend parallel to each other.

46. ​​The antenna of any one of claims 38-45, wherein each of the first to fourth dipole arms has a substantially rectangular perimeter except for first and second recesses on respective first and second sides of the substantially rectangular perimeter.

47. The antenna of claim 46, wherein the first recess on the first dipole arm faces the first recess on the second dipole arm, and the second recess on the first dipole arm faces the second recess on the fourth dipole arm.

48. An antenna comprising: Reflector; a first radiating element extending forwardly from the reflector, the first radiating element being configured to operate in a first operating frequency band; as well as a second radiating element extending forwardly from the reflector, the second radiating element being configured to operate in a second operating frequency band including higher frequencies than the first operating frequency band; The first radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator has a first dipole arm and a second dipole arm, the second dipole radiator has a third dipole arm and a fourth dipole arm, and The first dipole arm includes a first metal sheet having a first internal opening, wherein the first internal opening includes a first slot and a second slot intersecting the first slot at an angle of 90°.

49. The antenna of claim 48, wherein a perimeter of the first metal sheet completely surrounds the interior opening.

50. The antenna of claim 49, wherein the first radiating element is a dual-polarized radiating element configured to transmit and receive RF energy with respective first and second orthogonal linear polarizations, and wherein the first slot extends in the direction of the first linear polarization and the second slot extends in the direction of the second linear polarization.

51. An antenna according to claim 50, wherein the second dipole arm includes a second metal sheet substantially surrounding a second internal opening, and the second internal opening is configured so that a current induced on a first portion of the second metal sheet by the RF energy emitted by the second radiating element substantially offsets a current induced on a second portion of the second metal sheet by the RF energy emitted by the second radiating element, wherein the second internal opening includes a third slot and a fourth slot in the second metal region in which metal is omitted, and wherein a longitudinal axis of the third slot intersects a longitudinal axis of the fourth slot at an angle of 90°.

52. The antenna of claim 51, wherein the first slot and the third slot are co-linear, and wherein the second slot and the fourth slot extend parallel to each other.

53. An antenna according to any one of claims 49-52, wherein the first internal opening includes a central opening and a plurality of satellite openings, the first slot includes a first colinear segment and a second colinear segment extending radially from the central opening, the second slot includes a third colinear segment and a fourth colinear segment extending radially from the central opening, wherein a distal end of each of the first segment to the fourth segment terminates at a corresponding one of the satellite openings, and wherein a width of each of the first segment to the fourth segment is smaller than a width of a corresponding one of the satellite openings.

54. The antenna of any one of claims 48-53, wherein the first dipole arm has a substantially square outer perimeter, and the first slot and the second slot extend along respective diagonals of the square outer perimeter.

Images