Stealthy radiating elements with asymmetric dipole radiators and multiband base station antennas including such radiating elements

Abstract

A dual polarized radiating element includes a first dipole radiator having a first dipole arm extending generally along a first axis and a second dipole arm extending generally along a second axis different from the first axis, and a second dipole radiator having a third dipole arm extending generally along the first axis and a fourth dipole arm extending generally along a third axis different from the first axis. At least one of the first through fourth dipole arms can be a stealthed dipole arm including an inductive element configured to suppress current in a higher frequency band.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 994,962, filed March 26, 2020, the entire contents of which are incorporated herein by reference. Background Technology

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

[0004] Cellular communication systems are well known in the art. In a typical cellular communication system, a geographical area is divided into a series of areas called “cells,” each of which is served by a base station. A base station may include baseband equipment, a radio, and a base station antenna configured to provide bidirectional radio frequency (“RF”) communication with users located throughout the cell. In many cases, a cell may be divided into multiple “sectors,” and a separate base station antenna provides coverage for each sector. Antennas are typically mounted on towers, with the radiating beam (“antenna beam”) generated by each antenna pointing outward to serve the corresponding sector. Typically, a base station antenna comprises one or more phased arrays of radiating elements, wherein, when the antenna is installed and in use, the radiating elements are arranged in one or more vertical columns. Here, “vertical” means a direction perpendicular to a horizontal plane defined by the horizon. Reference will also be made to an azimuth plane that bisectes the horizontal plane of the base station antenna, and an elevation plane that extends along the direction of the antenna’s line of sight and is perpendicular to the azimuth plane.

[0005] A common base station configuration is a "three-sector" configuration, where the cell is divided into three 120° sectors in the azimuth plane. A base station antenna is provided for each sector. In a three-sector configuration, the antenna bundle generated by each base station antenna typically has a half-power beamwidth ("HPBW") in the azimuth plane at approximately 65°, allowing the antenna bundle to provide good coverage of the entire 120° sector. Three such base station antennas provide complete 360° coverage in the azimuth plane. Typically, each base station antenna will include one or more so-called "linear arrays" of radiating elements, which comprise multiple radiating elements arranged in a generally vertically extending column. Each radiating element may have an azimuth HPBW of approximately 65°, such that the antenna bundle generated by the linear array has an HPBW of approximately 65° in the azimuth plane. By providing a phased array of radiating elements extending along the elevation plane, the HPBW of the antenna bundle in the elevation plane can be narrowed to significantly less than 65°, with the amount of narrowing increasing with the length of the column in the vertical direction.

[0006] With the growth of cellular traffic, cellular operators have added new cellular services to various new frequency bands. When introducing these new services, it is often necessary to maintain existing "legacy" services to support older mobile devices. In some cases, it is possible to use a linear array of so-called "wideband" or "ultra-wideband" radiating elements to support services in the new frequency band. However, in other cases, it may be necessary to deploy additional linear arrays (or multi-row arrays) of radiating elements to support services in the new frequency band. Due to local zoning regulations and / or weight and wind load limitations, there are often restrictions on the number of base station antennas that can be deployed on a given base station. Therefore, to reduce the number of antennas, many operators deploy so-called "multi-band" base station antennas, which include multiple linear arrays of radiating elements that communicate in different frequency bands to support multiple different cellular services. In addition, with the introduction of fifth-generation (5G) cellular services, multi-row arrays of radiating elements are being added to base station antennas, which can support beamforming and / or massive multiple-input multiple-output ("MIMO") 5G services.

[0007] One type of multi-band base station antenna of interest includes a linear array of two “low-band” radiating elements for providing some or all of the 617-960 MHz band, and a massive MIMO array of “high-band” radiating elements operating in, for example, some or all of the 2.5-2.7 GHz, 3.4-3.8 GHz, or 5.1-5.8 GHz bands. Massive MIMO arrays typically have at least four columns of radiating elements, and up to thirty-two columns. Most proposed implementations include eight columns of radiating elements (or vertically stacked sets of eight columns to obtain sixteen or thirty-two columns). One example of such a base station antenna 10 is... Figure 1 The diagram is shown schematically.

[0008] See Figure 1 The base station antenna 10 includes a first linear array 20-1 and a second linear array 20-2 of low-frequency band radiating elements 22, and a multi-column array 40 of high-frequency band radiating elements 42, shown here in eight columns. The multi-column array 40 of high-frequency band radiating elements 42 can be a massive MIMO high-frequency band array. The radiating elements 22, 42 can be mounted to extend forward from the reflector 12, which can act as a ground plane for the radiating elements 22, 42. Figure 1 As shown, the low-frequency band linear array 20 typically extends the full length of the base station antenna 10. Multiple high-frequency band arrays 40 are positioned between the low-frequency band linear arrays 20-1 and 20-2. Note that in this document, similar elements may be assigned two parts of reference numerals. These elements may be individually referred to by their full reference numerals (e.g., low-frequency band linear array 20-2), and may be collectively referred to by the first part of their reference numerals (e.g., low-frequency band linear array 20).

[0009] However, base station antenna 10 may be difficult to implement in a commercially acceptable manner because achieving a 65° azimuth HPBW antenna bundle in the low-frequency band typically requires a low-frequency band radiating element, for example, approximately 200 mm (or greater). If the massive MIMO high-frequency band array 40 is positioned between the two low-frequency band linear arrays 20-1, 20-2, the base station antenna 10 will become wider than commercially acceptable (with a width, for example, greater than 500 mm). While the massive MIMO high-frequency band array 40 could alternatively be positioned above or below the low-frequency band arrays 20-1, 20-2 on reflector 12 to reduce the width of base station antenna 10, this would increase the length and cost of base station antenna 10 to a level that might be considered commercially unacceptable. Therefore, an improved base station antenna design is needed. Summary of the Invention

[0010] According to embodiments of the present invention, a dual-polarized radiating element for a base station antenna is provided, the dual-polarized radiating element comprising a first dipole radiator and a second dipole radiator. The first dipole radiator includes: a first dipole arm configured to have an average current direction extending along a first direction; and a second dipole arm configured to have an average current direction extending along a second direction, wherein the second direction forms a first tilt angle with the first direction. The second dipole radiator includes: a third dipole arm configured to have an average current direction extending along a third direction; and a fourth dipole arm configured to have an average current direction extending along a fourth direction, wherein the fourth direction forms a second tilt angle with the third direction.

[0011] In some embodiments, the first tilt angle may be substantially the same as the second tilt angle. In some embodiments, the first tilt angle and the second tilt angle may be obtuse angles, while in other embodiments, the first tilt angle and the second tilt angle may be acute angles.

[0012] In some embodiments, at least one of the first dipole arm and the second dipole arm may include a plurality of spaced-apart conductive members connected to each other via respective inductance trace segments.

[0013] In some embodiments, at least one of the first to fourth dipole arms may be in the form of a conductive ring. For example, all of the first to fourth dipole arms may be conductive rings, wherein each conductive ring includes a plurality of conductive members and a plurality of inductor trace segments, the inductor trace segments being narrower than the conductive members.

[0014] In some embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0015] In some embodiments, the first to fourth dipole arms may meet in the central region of the radiating element, and the first dipole arm may extend upward from the central region, the third dipole arm may extend downward from the central region, and both the second and fourth dipole arms may extend to a first side of the central region.

[0016] According to another embodiment of the present invention, a dual-polarized radiating element for a base station antenna is provided, the dual-polarized radiating element comprising a first dipole radiator and a second dipole radiator. The first dipole radiator includes a first dipole arm and a second dipole arm, the first dipole arm extending generally along a first axis, the second dipole arm extending generally along a second axis different from the first axis, and the second dipole radiator including a third dipole arm and a fourth dipole arm, the third dipole arm extending generally along the first axis, and the fourth dipole arm extending generally along a third axis different from the first axis. At least one of the first to fourth dipole arms includes a stealth dipole arm, the stealth dipole arm including an inductive element configured to suppress current in higher frequency bands.

[0017] In some embodiments, each of the first to fourth dipole arms may include a conductive ring. In some embodiments, each conductive ring may have a first segment and a spaced-apart opposing second segment, and the first segment of the first dipole arm may be substantially collinear with the first segment of the third dipole arm.

[0018] In some embodiments, each conductive ring may have a first segment and a spaced-apart opposing second segment, and the first segment of the second dipole arm may be substantially parallel to the first segment of the fourth dipole arm.

[0019] In some embodiments, the first to fourth dipole arms may each include a plurality of spaced-apart conductive members connected to each other via corresponding inductance trace segments.

[0020] In some embodiments, the first dipole arm may be configured to have an average current direction extending along a first direction, and the second dipole arm may be configured to have an average current direction extending along a second direction, wherein the first and second directions intersect to define an obtuse angle.

[0021] In some embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0022] In some embodiments, the first to fourth dipole arms may meet in the central region of the radiating element, and the first dipole arm may extend upward from the central region, the third dipole arm may extend downward from the central region, and both the second and fourth dipole arms may extend to a first side of the central region.

[0023] According to an additional embodiment of the invention, a dual-polarized radiating element for a base station antenna is provided, comprising a feed stem and a dipole radiator printed circuit board mounted on the feed stem. The dipole radiator printed circuit board includes first to fourth dipole arms extending from a central region, where the feed stem is electrically connected to the dipole radiator printed circuit board. The first dipole arm extends generally upward from the central region, the third dipole arm extends generally downward from the central region, and both the second and fourth dipole arms extend generally to a first side of the central region.

[0024] In some embodiments, each of the first to fourth dipole arms may include a conductive ring.

[0025] In some embodiments, the first dipole arm and the third dipole arm may form a first dipole radiator, and the second dipole arm and the fourth dipole arm may form a second dipole radiator.

[0026] In some embodiments, each conductive ring may have a first segment and an opposing second segment, and the first segment of the second dipole arm may extend substantially parallel to the first segment of the fourth dipole arm.

[0027] In some embodiments, the first segment of the first dipole arm may extend substantially collinearly with the first segment of the third dipole arm.

[0028] In some embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0029] In some embodiments, the first dipole arm may be configured to have an average current direction extending along a first direction, and the second dipole arm may be configured to have an average current direction extending along a second direction, wherein the first direction and the second direction intersect to define a first obtuse angle.

[0030] In some embodiments, the third dipole arm may be configured to have an average current direction extending along a third direction, and the fourth dipole arm may be configured to have an average current direction extending along a fourth direction, wherein the third direction and the fourth direction intersect to define a second obtuse angle.

[0031] In some embodiments, the first obtuse angle may be equal to the second obtuse angle.

[0032] In some embodiments, at least one of the first dipole arm and the second dipole arm may include a plurality of spaced-apart conductive members connected to each other via respective inductance trace segments.

[0033] According to another embodiment of the present invention, a dual-polarized radiating element for a base station antenna is provided, the dual-polarized radiating element comprising a first dipole radiator and a second dipole radiator. The first dipole radiator includes a first dipole arm and a second dipole arm, and the second dipole radiator includes a third dipole arm and a fourth dipole arm. The first dipole arm and the third dipole arm each include a spaced-apart first segment and a second segment, wherein the first segment of the first dipole arm is collinear with the first segment of the third dipole arm.

[0034] In some embodiments, the second dipole arm and the fourth dipole arm each include a spaced-apart first segment and a second segment, wherein the first segment of the first dipole arm is parallel to the first segment of the fourth dipole arm.

[0035] In some embodiments, the first segment of the first dipole arm may not be collinear with the first segment of the fourth dipole arm.

[0036] In some embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0037] In some embodiments, the first to fourth dipole arms may meet in the central region of the radiating element, and the first dipole arm may extend upward from the central region, the third dipole arm may extend downward from the central region, and both the second and fourth dipole arms may extend to a first side of the central region.

[0038] According to another embodiment, a base station antenna is provided, comprising a reflector; a first array including a first vertically extending column of low-frequency band radiating elements mounted forward from the reflector; a second array including a second vertically extending column of low-frequency band radiating elements mounted forward from the reflector; and a multi-column array of high-frequency band radiating elements located between the first and second arrays. Each of the first and second arrays includes at least one first-type radiating element horizontally adjacent to the multi-column array of high-frequency band radiating elements, and at least one second-type radiating element not horizontally adjacent to the multi-column array of high-frequency band radiating elements, wherein the first type differs from the second type. At least one radiating element in the first low-frequency band radiating element array includes a stealthy dipole arm with an inductive element configured to suppress current in the operating frequency band of the multi-column array.

[0039] In some embodiments, the low-frequency radiating elements of the first array may extend along a first side of the reflector, and the low-frequency radiating elements of the second array may extend along a second side of the reflector.

[0040] In some embodiments, a first type of radiating element may include: a first dipole radiator, the first dipole radiator including a first dipole arm and a second dipole arm, the first dipole arm being configured to have an average current direction extending along a first direction, the second dipole arm being configured to have an average current direction extending along a second direction, wherein the second direction forms a first tilt angle with the first direction; and a second dipole radiator, the second dipole radiator including a third dipole arm and a fourth dipole arm, the third dipole arm being configured to have an average current direction extending along a third direction, the fourth dipole arm being configured to have an average current direction extending along a fourth direction, wherein the third direction forms a second tilt angle with the fourth direction.

[0041] In some embodiments, the first tilt angle may be substantially the same as the second tilt angle. In some embodiments, the first tilt angle and the second tilt angle may be obtuse angles.

[0042] In some embodiments, at least one of the first to fourth dipole arms may be in the form of a conductive ring.

[0043] In some embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0044] In some embodiments, the second type of radiating element may include a cross-dipole radiating element comprising a pair of dipole radiators, each dipole radiator comprising two collinear dipole arms.

[0045] In some embodiments, a first type of radiating element may include a first to a fourth dipole arm that meets in a central region of the radiating element, with the first dipole arm extending upward from the central region, the third dipole arm extending downward from the central region, and both the second and fourth dipole arms extending to a first side of the central region.

[0046] In some embodiments, the first type of radiating element may include a first dipole radiator and a second dipole radiator, the first dipole radiator including a first dipole arm and a second dipole arm that is not collinear with the first dipole arm, and the second dipole radiator including a third dipole arm and a fourth dipole arm that is not collinear with the third dipole arm. Attached Figure Description

[0047] Figure 1 This is a schematic front view of a base station antenna that includes two linear arrays of low-frequency radiating elements and a large-scale MIMO array of high-frequency radiating elements.

[0048] Figure 2A This is a side perspective view of two conventional stealthy low-frequency band radiating elements used in base station antennas mounted on a feed plate.

[0049] Figure 2B yes Figure 2A A front view of one of the conventional stealthy low-frequency radiating elements.

[0050] Figure 3A This is a schematic diagram of a conventional "triple-polar" low-frequency radiating element.

[0051] Figure 3B yes Figure 3A A perspective view of a conventional implementation of a tripolar low-frequency band radiating element.

[0052] Figure 3C It shows the current direction in the dipole arm and the direction of the current. Figure 3B A schematic diagram of the polarization vector of the radiation pattern generated by the triode radiation element.

[0053] Figure 4A This is a perspective view of a base station antenna according to an embodiment of the present invention.

[0054] Figure 4B It involves removing the radome. Figure 4B A schematic front view of a base station antenna, showing the array of radiating elements included in the antenna.

[0055] Figure 5A This is a side perspective view of a modified tripolar low-frequency radiating element according to an embodiment of the present invention.

[0056] Figure 5B yes Figure 5A The front view of the modified tripolar low-frequency radiating element.

[0057] Figures 6A-6C yes Figure 5A A front view of the modified tripolar low-frequency radiating element, showing its operation.

[0058] Figure 7A This is a schematic front view of a base station antenna according to an embodiment of the present invention, which includes a hybrid linear array of low-frequency radiating elements.

[0059] Figure 7B yes Figure 7A A schematic top view of a base station antenna illustrates how the use of a stealthy tripolar low-frequency radiating element according to an embodiment of the invention provides space for more arrays of radiating elements in a large-scale MIMO array.

[0060] Figure 8A and 8B This is a schematic front view of a modified triode radiating element according to other embodiments of the present invention. Detailed Implementation

[0061] According to embodiments of the present invention, a low-frequency band radiating element is provided for use in a base station antenna, which also includes a massive MIMO array. The low-frequency band radiating element according to embodiments of the present invention may include a modified tripolar radiating element comprising a total of four dipole arms. Each dipole arm includes a generally upwardly extending dipole arm and a first generally laterally extending dipole arm that together form a first dipole radiator, and a generally downwardly extending dipole arm and a second generally laterally extending dipole arm that together form a second dipole radiator. The first and second laterally extending arms extend from the same side of an axis defined by the upwardly extending dipole arm and the downwardly extending dipole arm. The low-frequency band radiating element may be a stealthy low-frequency band radiating element configured to be substantially transparent to RF energy in the operating band of a massive MIMO array.

[0062] The first dipole arm can be configured such that when the first dipole radiator is excited, the current flowing in the first dipole arm will have an average current direction extending along a first direction, and the second dipole arm can be configured such that when the first dipole radiator is excited, the current flowing in the second dipole arm will have an average current direction extending along a second direction, wherein the second direction forms a first tilt angle with the first direction. Similarly, the third dipole arm can be configured such that when the second dipole radiator is excited, the current flowing in the third dipole arm will have an average current direction extending along a third direction, and the fourth dipole arm can be configured such that when the second dipole radiator is excited, the current flowing in the fourth dipole arm will have an average current direction extending along a fourth direction, wherein the third direction forms a second tilt angle with the fourth direction. In some embodiments, the first tilt angle and the second tilt angle may be obtuse angles, and the first dipole radiator and the second dipole radiator may be configured to transmit RF radiation having a -45° tilt polarization and a +45° tilt polarization. These radiating elements may be particularly suitable for use in base station antennas with multi-column arrays that operate in higher frequency bands than the radiating elements according to embodiments of the invention.

[0063] One problem with including arrays of radiating elements operating in different frequency bands within the same base station antenna is that undesirable interactions can occur between these elements. For example, radiation emitted by a higher-frequency-band radiating element can induce currents in the dipole arms of a nearby lower-frequency-band radiating element, which can distort the antenna beam generated by the higher-frequency-band radiating element. Such interactions can be reduced by increasing the spacing between the different arrays of radiating elements. However, when base station antennas include numerous arrays of radiating elements operating in different frequency bands, spatial separation becomes impractical.

[0064] So-called "stealthy" low-frequency band radiating elements have been developed, designed to be "transparent" to RF signals in the operating frequency band of nearby high-frequency band radiating elements. Figure 2A and 2B An example of a known stealthy dual-polarized low-frequency band radiating element 100 is shown, disclosed in U.S. Patent Publication No. 2018 / 0323513 (“'513 Publication”), filed February 15, 2018, the entire contents of which are incorporated herein by reference. The radiating element 100 produces both tilted-45° and tilted-45° radiation, and is commonly referred to as a “cross-dipole” radiating element because, when viewed from the front, it comprises two dipole radiators forming a cross shape. Figure 2A This is a side perspective view of two conventional stealthy low-frequency band radiating elements 100 in '513 Disclosure' mounted on feed plate 102. Figure 2BThis is a front view of one of the stealthy low-frequency radiating elements 100, which better illustrates the design of its dipole radiator.

[0065] like Figure 2A-2B As shown, each stealthy low-frequency radiating element 100 includes a feed handle 110 (which is in Figure 2A A first dipole radiator 120-1 and a second dipole radiator 120-2 (almost invisible in the mid-frequency band) are described. Dipole radiator 120-1 includes a pair of dipole arms 130-1, 130-2, and dipole radiator 120-2 includes a pair of dipole arms 130-3, 130-4. The length of each dipole arm 130 can be, for example, about 0.2 to 0.35 wavelengths of operating wavelength, where "operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of the radiating element 100. Each dipole arm 130 can be formed as a metal pattern on a printed circuit board 122, which includes a plurality of widened conductive elements or "components" 124 physically and electrically connected by narrow serpentine trace segments 126. The narrowed serpentine trace segments 126 are designed to act as high-impedance segments that interrupt current associated with radiation emitted by nearby mid-frequency band radiating elements (not shown) that would otherwise be induced on the dipole arms 130. Specifically, the narrowed serpentine trace segment 126 can function as an inductor, which helps interrupt current in the intermediate frequency band (IF band) while allowing current in the low frequency band to flow between adjacent widened conductive members 124. Therefore, the narrowed serpentine trace segment 126 can generate high impedance for IF band currents without significantly affecting the ability of low frequency band currents to flow on the dipole arm 130. Consequently, the narrowed serpentine trace segment 126 can reduce induced IF band currents on the low-frequency radiating element 100 and subsequently reduce interference with the antenna pattern of nearby IF band linear arrays (not shown).

[0066] While radiating element 100 can facilitate the compact packing of both low-band and mid-band linear arrays into a base station antenna, it is not ideal when both the low-band linear array and the massive MIMO high-band array are in the same antenna (as discussed above). Figure 1Other problems may arise when implementing antenna 10. Specifically, the high-frequency band radiating elements in a massive MIMO array are typically packed tightly together, which may leave no physical space between adjacent high-frequency band radiating elements to mount the feed handles for low-frequency band radiating elements. If this is the case, the feed handles for the low-frequency band radiating elements must be mounted on either side of the massive MIMO high-frequency band array. Considering the large physical size of the low-frequency band radiating elements and the width of an eight-column massive MIMO high-frequency band array, the antenna width can become very large. Furthermore, even though the feed handles for the low-frequency band radiating elements may potentially fit between clusters of high-frequency band radiating elements, in some applications the high-frequency band array must be a removable and replaceable modular array, which prevents the mounting of low-frequency band radiating elements within the coverage area of ​​the high-frequency band array.

[0067] Another known dual-polarized radiating element is the so-called "tripolar" radiating element. Figure 3A This is a schematic diagram illustrating the operation of a conventional triode radiating element, while Figure 3B yes Figure 3A Perspective views of an actual implementation of a triode radiating element. Both figures are taken from U.S. Patent No. 9,077,070, the entire contents of which are incorporated herein by reference. Figures 3A-3B As shown, the conventional triode radiating element 200 has three arms: a pair of side arms 220-1 and 220-2, and a central arm 230. The length of each arm 220, 230 can be approximately one-quarter wavelength of the center frequency of the operating band. Figure 3A As schematically shown, side arms 220-1 and 220-2 are connected to the center conductors of the corresponding coaxial feeds 210-1 and 210-2, while the center arm 230 is connected to the corresponding outer conductors of the coaxial feeds 210-1 and 210-2. The outer conductors of the coaxial feeds 210-1 and 210-2 are connected to the reflector R of the base station antenna. The tripolar radiating element 200 can be considered as a combination of two dipole radiators and arms bent at 90 degrees. (Reference) Figure 3C The equivalent diagram shows the current direction and the polarization vector of the radiation field (+45° and -45° tilt polarization) of the dipole arms 220 and 230. The +45° tilt and -45° tilt are relative to the side arms 210 and 220. Therefore, the side arms 220-1 and 220-2 can be oriented horizontally or vertically relative to the longitudinal axis of the reflector R to achieve + / -45° tilt polarization.

[0068] The tripolar radiator 200 is physically smaller than a conventional crossed dipole radiator. Furthermore, the feed stem 210 for the tripolar radiator 200 is not located directly behind the center of the radiator 200 as is the case with most conventional crossed dipole radiators, but is instead offset to one side. Therefore, the column of tripolar radiators 200 can be mounted on either side of the high-frequency band array, without extending the width of the antenna as a conventional crossed dipole radiator array would.

[0069] Unfortunately, when low-frequency and high-frequency radiating elements are placed close together, undesirable interactions may occur between them, similar to those between low-frequency and mid-frequency radiating elements discussed above. These interactions can lead to scattering of the high-frequency RF signal, which can adversely affect various characteristics of the high-frequency antenna beam, including azimuth and elevation beamwidth, beam slant, beam pointing angle, gain, front-to-back ratio, and cross-polarization differentiation. Furthermore, the effects of scattering can vary significantly with frequency, making it difficult to compensate for these effects using other techniques.

[0070] As described above, according to embodiments of the present invention, a modified tripole radiating element is provided for a base station antenna, which allows for a compact base station antenna having a large-scale MIMO high-frequency band array between a pair of low-frequency band linear radiating element arrays. The modified tripole radiating element according to embodiments of the present invention can be a stealthy radiating element and can be mounted very close to the edge of the base station antenna's reflector. In some embodiments, the low-frequency band linear array can be implemented entirely using the modified tripole radiating element according to embodiments of the present invention. However, in other embodiments, the low-frequency band linear array may comprise a mixture of cross dipoles and modified tripole radiating elements, which may provide enhanced performance in some applications.

[0071] According to some embodiments, a dual-polarized radiating element is provided, comprising a first dipole radiator having a first dipole arm and a second dipole arm, the first dipole arm being configured to have an average current direction extending along a first direction, and the second dipole arm being configured to have an average current direction extending along a second direction, wherein the second direction forms a first tilt angle with the first direction. These dual-polarized radiating elements also include a second dipole radiator having a third dipole arm and a fourth dipole arm, the third dipole arm being configured to have an average current direction extending along a third direction, and the fourth dipole arm being configured to have an average current direction extending along a fourth direction, wherein the third dipole arm forms a first tilt angle with the fourth direction.

[0072] In some embodiments, the first tilt angle and the second tilt angle may be obtuse angles. In other embodiments, the first tilt angle and the second tilt angle may be acute angles. In some embodiments, the first tilt angle and the second tilt angle may be the same. In each of these embodiments, the first dipole radiator may be configured to emit RF radiation with a -45° tilt polarization, and the second dipole radiator may be configured to emit RF radiation with a +45° tilt polarization.

[0073] According to an additional embodiment, a dual-polarized radiating element is provided, comprising a first dipole radiator and a second dipole radiator. The first dipole radiator has a first dipole arm extending generally along a first axis and a second dipole arm extending generally along a second axis different from the first axis. The second dipole radiator has a third dipole arm extending generally along the first axis and a fourth dipole arm extending generally along a third axis different from the first axis. At least one of the first to fourth dipole arms may be a stealthy dipole arm including an inductive element configured to suppress current in higher frequency bands.

[0074] According to other embodiments, a dual-polarized radiating element is provided, comprising a feed handle and a dipole radiator printed circuit board mounted on the feed handle. The dipole radiator printed circuit board includes a first dipole arm to a fourth dipole arm extending from a central region, wherein the feed handle is electrically connected to the dipole radiator printed circuit board in the central region. The first dipole arm extends generally upward from the central region, the third dipole arm extends generally downward from the central region, and both the second and fourth dipole arms extend generally to a first side of the central region.

[0075] According to other embodiments, a dual-polarized radiating element is provided, comprising a first dipole radiator and a second dipole radiator. The first dipole radiator includes a first dipole arm and a second dipole arm, and the second dipole radiator includes a third dipole arm and a fourth dipole arm. The first and third dipole arms each include a spaced-apart first segment and a second segment, wherein the first segment of the first dipole arm is collinear with the first segment of the third dipole arm. The second and fourth dipole arms may each include a spaced-apart first segment and a second segment, wherein the first segment of the second dipole arm is parallel to the first segment of the fourth dipole arm. The first segment of the second dipole arm may not be collinear with the first segment of the fourth dipole arm.

[0076] According to other aspects of the invention, a base station antenna is provided, comprising a reflector; a first array including a first vertically extending column of low-frequency band radiating elements mounted forward from the reflector; a second array including a second vertically extending column of low-frequency band radiating elements mounted forward from the reflector; and a multi-column array of high-frequency band radiating elements located between the first and second arrays. Each of the first and second arrays includes at least one first-type radiating element horizontally adjacent to the multi-column array of high-frequency band radiating elements, and at least one different second-type radiating element not horizontally adjacent to the multi-column array of high-frequency band radiating elements. At least one radiating element in the first low-frequency band radiating element array includes a stealthy dipole arm with an inductive element configured to suppress current in the operating frequency band of the multi-column array.

[0077] In some embodiments, the low-frequency radiating elements of the first array extend along a first side of the reflector, and the low-frequency radiating elements of the second array extend along a second side of the reflector. In some embodiments, the first type of radiating element includes any radiating element disclosed herein according to embodiments of the invention. In some embodiments, the second type of radiating element may include a crossed dipole radiating element comprising a first dipole radiator having a first collinear dipole arm and a second collinear dipole arm, and a second dipole radiator having a third collinear dipole arm and a fourth collinear dipole arm.

[0078] Now refer to Figure 4A-8B Embodiments of the present invention will be described in more detail below.

[0079] Figure 4A and 4B A base station antenna 300 according to certain embodiments of the present invention is shown. Specifically, Figure 4A This is a perspective view of base station antenna 300, and Figure 4B This is a front view of a base station antenna 300, with the radome removed, which schematically shows a linear array of radiating elements included in the antenna 300.

[0080] like Figures 4A-4B As shown, the base station antenna 300 is an elongated structure extending along the longitudinal axis L. The base station antenna 300 may have a tubular shape with a generally rectangular cross-section. The antenna 300 includes an radome 310 and a bottom end cap 312. A plurality of RF connectors 314 may be mounted in the bottom end cap 312. The antenna 300 is typically mounted in a vertical configuration (i.e., when the antenna 300 is mounted for normal operation, the longitudinal axis L may be generally perpendicular to the plane defined by the horizon).

[0081] refer to Figure 4BThe base station antenna 300 includes an antenna assembly 316 that can be slidably inserted into an antenna radome 310. The antenna assembly 316 includes a base plate structure 318 that can serve as a ground plane and a reflector for the antenna 300.

[0082] A first low-frequency band linear array 320-1 and a second low-frequency band linear array 320-2, each comprising multiple low-frequency band radiating elements, are mounted to extend forward from the reflector 318. Each low-frequency band linear array 320 includes two different types of low-frequency band radiating elements, namely low-frequency band radiating elements 322 and low-frequency band radiating elements 324. First to fourth intermediate-frequency band linear arrays 330-1 to 330-4, each comprising multiple intermediate-frequency band radiating elements 332, are also mounted to extend forward from the reflector 318. The first intermediate-frequency band linear array 330-1 and the fourth intermediate-frequency band linear array 330-4 are mounted on the left and right edges of the reflector 318, outside the corresponding first and second low-frequency band linear arrays 320-1 and 320-2. The second intermediate-frequency band linear array 330-2 and the third intermediate-frequency band linear array 330-3 are mounted between the first low-frequency band linear array 320-1 and the second low-frequency band linear array 320-2.

[0083] The first low-frequency band linear array 320-1 and the second low-frequency band linear array 320-2 each substantially extend the full length of the reflector 318. The first to fourth mid-frequency band linear arrays 330-1 to 330-4 are mounted along the lower portion 318A of the reflector 318 and do not extend the full length of the reflector 318. As described above, the first low-frequency band linear array 320-1 and the second low-frequency band linear array 320-2 each include two different types of radiating elements 322, 324. Radiating element 322 is a cross-dipole radiating element, which includes a first dipole radiator and a second dipole radiator arranged at angles of +45° and -45° relative to the horizon when the base station antenna 300 is mounted for use. Radiating element 322 can be implemented, for example, using any of the stealthy cross-dipole low-frequency band radiating elements disclosed in the aforementioned '513 disclosure, but embodiments of the invention are not limited thereto. The bottom four low-frequency band radiating elements of each low-frequency band linear array 320 are implemented as radiating elements 322. The radiating element 322 can be entirely located in the lower portion 318A of the base station antenna 300.

[0084] According to an embodiment of the invention, the radiating element 324 is a modified triode radiating element, which will be referenced below. Figure 5A-8B A more detailed discussion follows.

[0085] like Figure 4BAs further shown, the base station antenna 300 further includes a multi-column high-frequency band array 340 of high-frequency band radiating elements 342. The multi-column high-frequency band array 340 is located between the low-frequency band linear arrays 320-1 and 320-2 in the upper part 318B of the antenna 300, and between the three modified triode radiating elements 324 included in each low-frequency band linear array 320-1 and 320-2.

[0086] To reduce the width W of the antenna 300, the outer row of the radiating elements 342 in the high-frequency band array 340 can be very close to the triode radiating elements 324. Although Figure 4B Not shown, but the low-frequency radiating element 324 extends further forward from the reflector 318 than the high-frequency radiating element 342, and a portion of the low-frequency radiating element 324 can “cover” some of the high-frequency radiating element 342, meaning that the axis perpendicular to the reflector 318 can extend through both the low-frequency radiating element 322 and the high-frequency radiating element 342.

[0087] In an exemplary embodiment, low-frequency radiating elements 322 and 324 may each be configured to transmit and receive signals in at least a portion of the 617-960 MHz frequency range. Mid-frequency radiating element 332 may be configured to transmit and receive signals in a higher frequency range than low-frequency radiating elements 322 and 324, such as the 1427-2690 MHz frequency range or a smaller portion thereof. High-frequency radiating element 342 may be configured to transmit and receive signals in a higher frequency range than mid-frequency radiating element 332, such as the 3.4-3.8 GHz and / or 5.1-5.8 GHz frequency range or a smaller portion thereof. In some cases, high-frequency radiating element 342 may be configured to transmit and receive signals in the upper portion of the mid-band frequency range, such as 2.5-2.7 GHz. However, it should be understood that embodiments of the invention are not limited to the exemplary embodiments discussed above.

[0088] All radiating elements 322, 324, 332, and 342 can include dual-polarized radiating elements. Therefore, each array 320, 330, and 340 can be used to form two separate antenna bundles: one with +45° tilt polarization and the other with -45° tilt polarization. It should be recognized that some or all of the radiating elements in a linear array may be imperfectly aligned along the vertical axis, but some of the radiating elements can be horizontally staggered relative to other radiating elements in a particular array. Such staggering... Figure 4B As shown, the tripole radiating element 324 is positioned closer to the side of the reflector 318 than the crossed dipole radiating element 322. For example, an interleaved linear array can be used to narrow the azimuth beamwidth of the antenna beam generated by the linear array.

[0089] Figure 5AThis is a side perspective view of the tripolar low-frequency band radiating element 400 according to an embodiment of the present invention. Figure 5B yes Figure 5A A front view of a stealthy tripolar low-frequency radiating element 400. For example, a tripolar low-frequency radiating element 400 can be used to implement a low-frequency radiating element 324 included in a base station antenna 300. Note that a tripolar radiating element according to an embodiment of the invention may include four dipole arms. However, they are still referred to herein as “tripolar” radiating elements or “modified tripolar” radiating elements because the overall design of the radiating element is more similar to a tripolar radiating element compared to a conventional cross-polarized radiating element.

[0090] refer to Figures 5A-5B In the design, the stealthy tripolar low-frequency radiating element 400 includes a pair of feed handles 410-1 and 410-2, and a first dipole radiator 420-1 and a second dipole radiator 420-2. The first dipole radiator 420-1 includes a first dipole arm 430-1 and a second dipole arm 430-2, and the second dipole radiator 420-2 includes a third dipole arm 430-3 and a fourth dipole arm 430-4. The first dipole arm 430-1 and the third dipole arm 430-3 extend generally along a first vertical axis A1, and the second dipole arm 430-2 and the fourth dipole arm 430-4 extend generally along corresponding second axes A2 and third axes A3, which serve as horizontal axes. Therefore, the tripolar radiating element 400 includes: a first dipole radiator 420-1 having a first dipole arm 430-1 extending generally along a first (vertical) axis A1 and a second dipole arm 430-2 extending generally along a second (horizontal) axis A2; and a second dipole radiator 420-2 having a third dipole arm 430-3 extending generally along the first vertical axis A1 and a fourth dipole arm extending generally along a third (horizontal) axis A3.

[0091] When viewed from the front, the first dipole radiator 420-1 and the second dipole radiator 420-2 together have a shape resembling a Greek letter. Figure 5B (Side rotation in the view). In the depicted embodiment, dipole radiators 420-1, 420-2 are implemented on a common printed circuit board 422, but in other embodiments multiple printed circuit boards may be used, and / or dipole radiators 420-1, 420-2 may be implemented using metal sheets or other methods.

[0092] The feed stem 410 may extend in a direction generally perpendicular to the plane defined by the printed circuit board 422. The feed stem 410 may have an RF transmission line 412 formed thereon (see...). Figure 5A ), the RF transmission line is used between the dipole radiator 420 and the base station antenna including the triode radiating element 400 (e.g., Figures 4A-4B The base station antenna 300 transmits RF signals between its feed network. The feed arm 410 can be used to mount the dipole radiator 420 at a suitable distance in front of the reflector 318 of the base station antenna 300, typically at approximately 3 / 16 to 1 / 4 of the operating wavelength. "Operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of the radiating element 400. Furthermore, although the dipole radiators 420-1, 420-2 extend in a plane generally parallel to the plane defined by the reflector below, it should be appreciated that in other embodiments, the dipole arms 420-1, 420-2 may be rotated 90° along their respective longitudinal axes to be perpendicular to the reflector (or rotated at some other angle). The low-frequency band radiating element 400 may, for example, be designed to operate in some or all of the 617-960 MHz frequency band.

[0093] Figure 5B This is a front view of the radiating element 400, which more clearly shows the design of forming dipole radiators 420-1, 420-2 and dipole arms 430-1 to 430-4 forming dipole radiators 420.

[0094] refer to Figure 5B As can be seen, in the radiating element 400, the first to fourth dipole arms 430-1 to 430-4 each extend from the central region of the printed circuit board 422, in which the feed handles 410-1 and 410-2 are electrically connected to the dipole radiator printed circuit board 422. The first dipole arm 430-1 extends generally upward from the central region, the third dipole arm 430-3 extends generally downward from the central region, and both the second dipole arm 430-2 and the fourth dipole arm 430-4 extend generally to the first side of the central region.

[0095] For example Figure 5B As shown, the first dipole arm 430-1 and the third dipole arm 430-3 each include a spaced-apart first segment 434-1 and a second segment 434-2, wherein the first segment 434-1 of the first dipole arm 430-1 is collinear with the first segment 434-1 of the third dipole arm 430-3. The second dipole arm 430-2 and the fourth dipole arm 430-4 may each include a spaced-apart first segment 434-1 and a second segment 434-2, wherein the first segment 434-1 of the second dipole arm 430-2 is parallel to the first segment 434-1 of the fourth dipole arm 430-4. In some embodiments, the first segment 434-1 of the second dipole arm 430-2 may be parallel to the first segment 434-1 of the fourth dipole arm 430-4, but not collinear with the first segment of the fourth dipole arm.

[0096] Each dipole arm 430 can be formed as a metal pattern on a printed circuit board 422. Each metal pattern includes a plurality of widened conductive members 424, which are connected by narrowed trace segments 426. The narrowed trace segments 426 can be implemented as serpentine conductive traces. Here, a serpentine conductive trace refers to a non-linear conductive trace that follows a serpentine path to increase its path length. The serpentine conductive trace segments 426 may have extended lengths but still have a small physical coverage area.

[0097] like Figure 5B As shown, each dipole arm 430 may include a ring comprising a series of alternating widened conductive members 424 and narrowed trace segments 426. Each pair of adjacent widened conductive members 424 may be physically and electrically connected by a corresponding one of the narrowed trace segments 426. Because the narrowed trace segments 426 have a small physical coverage area, adjacent widened conductive members 424 can be brought close together such that the widened conductive members 424 together present as a single dipole arm at frequencies within the operating frequency range of the low-frequency band radiating element 400. It should be appreciated that in other embodiments, the dipole arm does not need to have a closed-loop design as explained in, for example, the '513 disclosure (e.g., the distal ends of the two segments forming the ring may not be electrically connected to each other).

[0098] like Figure 5B As best shown, the widened conductive member at the base or "root" of each dipole arm 430 has a slot 428 formed therethrough. These slots 428 extend through a printed circuit board 422. A tab (not shown) on each feed handle 410 (which may be a feed handle printed circuit board) can extend through the corresponding slot 428, thereby allowing the feed handle to be electrically connected to the corresponding dipole arm 430 via a current or capacitive connection. When the radiating element 400 is viewed from the front, the feed handle 410 can be positioned directly behind the slot 428. As is apparent, the feed handle 410 is not positioned at the horizontal center of the radiating element 400, but is offset to one side. Thus, the radiating element 400 can be positioned closer to the reflector of the base station antenna than, for example, the cross dipole radiating element 200 discussed above.

[0099] like Figure 5B As shown, dipole arms 430-1 to 430-4 can have similar designs. Although in Figures 5A-5BWhile not visible in the foreground, some or all of the widened conductive members 424 located on the front side of the printed circuit board 422 may optionally be replicated on the back side of the printed circuit board 422 and may be aligned with the widened conductive members 424 located on the front side of the printed circuit board 422. In embodiments including widened conductive members 424 located on the back side of the printed circuit board 422, metal-plated vias (not shown) may be used to electrically connect the widened conductive members 424 on the front side of the printed circuit board 422 to widened conductive members 424 on the rear side of the printed circuit board 422, or alternatively, widened conductive members 424 on opposite sides of the printed circuit board 422 may be capacitively coupled to each other. Providing widened conductive members 424 on both sides of the printed circuit board 422 may help increase the operating bandwidth of the low-frequency radiating element 400.

[0100] The narrowed serpentine trace segment 426 is designed to act as a high-impedance segment that interrupts the current associated with nearby high-frequency band radiating elements (e.g., high-frequency band radiating element 342 of the base station antenna 300), a current that would otherwise be induced on the dipole arm 430. As discussed above, when the nearby high-frequency band radiating element 342 transmits and receives signals, the high-frequency band RF signal may tend to induce current on the dipole arm 430 of the low-frequency band radiating element 400. This is especially true when the low-frequency band and high-frequency band radiating elements are designed to operate in frequency bands approximately four times apart, with a center frequency, because the low-frequency band dipole arm 430, having a length of a quarter wavelength for the low-frequency band operating frequency, in this case has a length of approximately the full wavelength for the high-frequency band operating frequency. The greater the degree to which high-frequency band current is induced on the low-frequency band dipole arm 430, the greater the impact on the characteristics of the radiation mode of the high-frequency band array. The narrowed serpentine trace segment 426 is designed to generate high impedance for high-frequency band currents without significantly affecting the ability of low-frequency band currents to flow on the dipole arm 430. In some embodiments, the narrowed trace segment 426 can make the low-frequency band radiating element 400 invisible to nearby high-frequency band radiating elements, and thus the low-frequency band radiating element 300 can avoid distorting the high-frequency band antenna pattern.

[0101] Each widened conductive member 424 may have a corresponding width W1, wherein the width W1 is measured in a direction substantially perpendicular to the current flow direction along the corresponding widened conductive member 424. The width W1 of each widened conductive member 424 need not be constant. Similarly, the narrowed trace segment 426 may have a width W2, wherein the width W2 is measured in a direction substantially perpendicular to the instantaneous current flow direction along the narrowed trace segment 426. The width W2 of each narrowed trace segment 426 need not be constant. In some embodiments, the average width of each widened conductive member 424 may be, for example, at least twice the average width of each narrowed trace segment 426. In other embodiments, the average width of each widened conductive member 424 may be at least three times, at least five times, or at least seven times the average width of each narrowed trace segment 426.

[0102] Figures 6A-6C yes Figure 5A A front view of the stealthy tripolar low-frequency radiating element 400, illustrating its operation. (See image.) Figure 6A As shown, dipole radiators 420-1 can be excited by feeding RF signals to dipole arms 430-1 and 430-2. In this embodiment, the radiating element 400 is designed such that it excites an equal amount of current to each dipole arm 430-1 and 430-2 in response to the RF feed signal. Focusing on dipole arm 430-1, the average current direction along the dipole arm is shown by a line segment labeled 432-1. Similarly, on dipole arm 430-2, the average current direction along the dipole arm is shown by a line segment labeled 432-2. The segments 432-1 and 432-2, representing the average current directions along dipole arms 430-1 and 430-2 respectively, intersect at an angle ·1. Angle ·1 is an inclination angle, and more specifically, in the depicted embodiment, it is an obtuse angle.

[0103] Figure 6B The desired polarization of the antenna beam generated by the dipole radiator 420-1 (which includes dipole arms 430-1, 430-2) is shown, which is a -45° tilt polarization.

[0104] Figure 6CThe average current direction along each dipole arm 430 and the polarization of the antenna beams generated by dipole radiators 420-1 and 420-2 are shown. The average current directions 432-1 and 432-2 for dipole arms 430-1 and 430-2 have been discussed above. The average current direction along dipole arm 430-3 is shown by a line segment labeled 432-3, and the average current direction along dipole arm 430-4 is shown by a line segment labeled 432-4. Line segments 432-3 and 432-4 intersect at an angle ·2. Angle ·2 is a tilt angle, and more specifically, in the depicted embodiment, it is an obtuse angle. Dashed line 436-1 shows the polarization of dipole radiator 420-1, while dashed line 436-2 shows the polarization of dipole radiator 420-2. As can be seen, dipole radiators 420-1 and 420-2 generate antenna beams with tilt polarizations of -45° and +45°, respectively. Therefore, angles ·1 and ·2 are chosen such that, given the average current direction along the dipole arms of dipole radiators 420-1 and 420-2, the dipole radiators will generate antenna beams with tilt polarizations of -45° and +45°, respectively.

[0105] As discussed above, according to embodiments of the present invention, a base station antenna is provided comprising at least one vertically extending low-frequency band linear array and multiple columns of high-frequency arrays. The at least one low-frequency band linear array may include at least two different types of low-frequency band radiating elements. Figure 4B This base station antenna is shown schematically. Figure 7A and 7B Another example of this base station antenna 300' is shown. Specifically, Figure 7A This is a schematic front view of the base station antenna 300', and Figure 7B This is a schematic top view of base station antenna 300', which illustrates how the use of a modified tripolar radiating element according to an embodiment of the invention provides space for more rows of radiating elements in a large-scale MIMO array.

[0106] like Figure 7AAs shown, the base station antenna 300' includes a reflector 310, a first low-frequency band array 320-1 including low-frequency band radiating elements 322, 324 in a first vertically extending column, mounted to extend forward from the reflector 310; a second low-frequency band array 320-2 including low-frequency band radiating elements 322, 324 in a second vertically extending column, mounted to extend forward from the reflector 310; and a multi-column array 340 of high-frequency band radiating elements (not shown separately) located between the first low-frequency band array 320-1 and the second low-frequency band array 320-2. Each low-frequency band array 320 may extend most or all of the length of the base station antenna 300'. In contrast, the high-frequency band array 340 may be shorter and, in the depicted embodiment, is located in the upper half of the base station antenna 300'.

[0107] The first low-frequency band array 320-1 and the second low-frequency band array 320-2 each include two different types of radiating elements: a cross-dipole radiating element 322 according to embodiments of the present invention and a modified triode radiating element 324. As can be seen, the cross-dipole low-frequency band radiating element 322 is used for portions of the linear arrays 320-1 and 320-2 that are not horizontally adjacent to the high-frequency band array 340, while the modified triode radiating element 324 according to certain embodiments of the present invention is used for portions of the linear arrays 320-1 and 320-2 that are horizontally adjacent to the high-frequency band array 340. As shown, the modified triode radiating element 324 can be positioned significantly closer to the side edge of the reflector 310 than the cross-dipole radiating element 322. Therefore, there is more space in the upper middle part of the reflector 310 of the high-frequency band array 340. Figure 7A As shown, the modified tripolar radiating element 324 can be positioned such that its dipole arm extends substantially to the edge of the reflector 310 in order to reduce the width of the base station antenna 300'. This can slightly reduce the performance of the low-frequency band array 320 because the modified tripolar radiating elements 324 do not have an optimal number of reflectors behind them, but this reduction is generally acceptable, especially since most of the radiating elements 322 in the low-frequency band array 320 are positioned more inward on the reflector 310. Additionally, this arrangement of the modified tripolar radiating elements 324 being positioned more outward than the crossed dipole radiating elements 322 creates horizontal staggering in the linear array 320, which can help narrow the azimuth beamwidth of the antenna beam generated by the low-frequency band linear array. This can result in enhanced performance and / or allow the use of slightly smaller low-frequency band radiating elements 322, 324, both of which are beneficial.

[0108] The modified triode radiating element 324 is implemented as a stealth radiating element, which is substantially transparent to RF energy in the operating band of the high-frequency band array 340. The cross-dipole radiating element 322 is also implemented as a stealth radiating element because, although not shown, the additional array of radiating elements can be mounted on the lower portion of the reflector 310. The cross-dipole radiating element 322 can be designed to be transparent to RF energy in the operating band of any such array. For example, as referenced above... Figure 4B The mid-frequency band radiating elements of the multiple linear arrays may be included in the antenna 300'. If the base station antenna 300 includes such a mid-frequency band linear array, the cross dipole radiating element 322 may be designed to be transparent to some or all of the RF energy in, for example, the 1427-2690 MHz band.

[0109] Figure 8A and 8B This is a schematic front view of a modified tripolar low-frequency radiating element according to other embodiments of the present invention.

[0110] refer to Figure 8A The modified tripolar radiating element 500 includes a first dipole radiator with dipole arms 530-1 and 530-2 and a second dipole radiator with dipole arms 530-3 and 530-4. Although the dipole arms 530 are... Figure 8A As indicated by the bolded line segment, it should be recognized that any dipole arm design can be used to form dipole arms, including straight dipole arms (which may or may not be stealthy designs), toroidal dipole arms, leaf-shaped dipole arms, etc. The modified tripolar radiating element 500 differs from the modified tripolar radiating element 400 discussed above in that dipole arms 530-1 and 530-3 do not extend along a common vertical axis, but instead each dipole arm 530-1, 530-3 is angled relative to the vertical axis. Similarly, dipole arms 530-2 and 530-4 do not extend along their respective horizontal axes, but instead each dipole arm 530-2, 530-4 is angled relative to the horizontal. As a result, the axes defined by dipole arms 530-1, 530-2 intersect to define an obtuse angle ·1, and the axes defined by dipole arms 530-3, 530-4 intersect to define an obtuse angle ·2. Obtuse angles ·1 and ·2 can be selected such that dipole radiator 520-1 will emit radiation with a -45° tilt polarization, and dipole radiator 520-2 will emit radiation with a +45° tilt polarization.

[0111] refer to Figure 8B The modified tripolar radiating element 600 includes a first dipole radiator and a second dipole radiator. The first dipole radiator includes dipole arms 630-1 and 630-2; the second dipole radiator includes dipole arms 630-3 and 630-4. Although dipole arms 630 are... Figure 8B As indicated by the bolded line segment, it should be recognized that any dipole arm design can be used to form a dipole arm, including straight dipole arms (which may or may not be stealthy designs), toroidal dipole arms, leaf-shaped dipole arms, etc. The modified tripolar radiating element 600 differs from the modified tripolar radiating element 500 discussed above, except that dipole arms 630-1 and 630-2 intersect to define an acute angle ·3 instead of an obtuse angle. Dipole arms 630-1 and 630-2 are configured such that the emitted radiation will have a -45° tilt polarization. Similarly, dipole arms 630-3 and 630-4 intersect to define an acute angle ·4 instead of an obtuse angle. Dipole arms 630-3 and 630-4 are configured such that the emitted radiation will have a +45° tilt polarization.

[0112] although Figures 5A-5B All dipole arms 430 of the radiating element 400 are shown to be stealth dipole arms, but embodiments of the invention are not limited thereto. For example, in alternative embodiments, only dipole arms 430-2 and 430-4 may be constructed as stealth dipole arms, and dipole arms 430-1 and 430-3 may be constructed as non-stealth dipole arms (e.g., straight metal arms, metal leaves, etc.). Therefore, it should be appreciated that many modifications can be made to the radiating element 400, for example, without departing from the scope of the invention.

[0113] It should also be recognized that the currents on the two dipole arms of the dipole radiator according to an embodiment of the invention are not necessarily equal. In the case of unequal currents, the angle defined by the intersection of the two dipole arms is modified so that the polarization of the radiation pattern generated by the dipole radiator will have a + / -45° tilt polarization.

[0114] The triode radiating elements according to embodiments of the present invention facilitate the implementation of two low-frequency band arrays and a massive MIMO high-frequency band array in the same base station antenna while keeping the antenna width within a reasonable size. They also facilitate the use of modular massive MIMO arrays within the base station antenna because they allow the low-frequency band radiating elements to be positioned very close to the side edges of the reflector. The stealthy design allows the triode radiating elements to be substantially invisible to radiation emitted by the high-frequency band radiating elements, and therefore substantially does not affect the characteristics of the high-frequency band antenna bundle.

[0115] Although the above discussion focuses on low-frequency radiating elements, it should be recognized that the techniques discussed above can be used with radiating elements operating in any suitable frequency band.

[0116] Embodiments of the invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are illustrated. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Throughout the text, the same numerals denote the same elements.

[0117] It will be understood that although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0118] It will be understood that when an element is described as being “on” another element, that element may be directly on the other element, or there may be intermediate elements. 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, that element may be directly connected or coupled to the other element, or there may be intermediate elements. Conversely, when an element is described as being “directly connected” or “directly coupled” to another element, there are no intermediate elements. Other terms used to describe relationships between elements should be interpreted in a similar manner (i.e., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).

[0119] Relative terms, such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical”, may be used herein to describe the relationship of one element, layer, or region to another element, layer, or region, as illustrated in the accompanying drawings. It should be understood that these terms are intended to cover different orientations of the device other than those depicted in the drawings.

[0120] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the terms “comprising,” “including,” and / or “having” as used herein mean the presence of the stated features, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

[0121] All aspects and elements of the embodiments disclosed above may be combined in any way and / or combined with aspects or elements of other embodiments to provide multiple additional embodiments.

Claims

1. A dual-polarized radiating element for a base station antenna, comprising: feed handle; A first dipole radiator mounted on the front end of the feed handle, the first dipole radiator comprising: a first dipole arm configured to have an average current direction extending along a first direction; and a second dipole arm configured to have an average current direction extending along a second direction, wherein the second direction forms a first tilt angle with the first direction; A second dipole radiator is mounted on the front end of the feed handle. The second dipole radiator includes: a third dipole arm configured to have an average current direction extending along a third direction; and a fourth dipole arm configured to have an average current direction extending along a fourth direction, wherein the fourth direction forms a second tilt angle with the third direction. The first to fourth dipole arms meet in the central region of the radiating element, and when viewed from the front, the first dipole arm extends upward from the central region, the third dipole arm extends downward from the central region, and both the second and fourth dipole arms extend to a first side of the central region.

2. The dual-polarized radiating element according to claim 1, wherein the first tilt angle is substantially the same as the second tilt angle.

3. The dual-polarized radiating element according to claim 1, wherein the first tilt angle and the second tilt angle are a first obtuse angle and a second obtuse angle.

4. The dual-polarized radiating element according to claim 1, wherein the first tilt angle and the second tilt angle are a first acute angle and a second acute angle.

5. The dual-polarized radiating element according to any one of claims 1-4, wherein at least one of the first dipole arm and the second dipole arm comprises a plurality of spaced-apart conductive members, the plurality of spaced-apart conductive members being connected to each other via respective inductance trace segments.

6. The dual-polarized radiating element according to any one of claims 1-4, wherein at least one of the first to fourth dipole arms is in the form of a conductive ring.

7. The dual-polarized radiating element according to claim 6, wherein all dipole arms from the first dipole arm to the fourth dipole arm include a conductive ring, wherein each conductive ring includes a plurality of conductive members and a plurality of inductor trace segments, the inductor trace segments being narrower than the conductive members.

8. The dual-polarized radiating element according to any one of claims 1-4, wherein the first dipole radiator is configured to emit RF radiation with a tilted -45° polarization, and the second dipole radiator is configured to emit RF radiation with a tilted +45° polarization.

9. A dual-polarized radiating element for a base station antenna, comprising: feed handle; A first dipole radiator is mounted on the front end of the feed handle. The first dipole radiator includes a first dipole arm that extends generally along a first axis and a second dipole arm that extends generally along a second axis different from the first axis. as well as A second dipole radiator is mounted on the front end of the feed handle. The second dipole radiator includes a third dipole arm extending generally along the first axis and a fourth dipole arm extending generally along a third axis different from the first axis. At least one of the first to fourth dipole arms includes a stealth dipole arm, which includes an inductive element configured to suppress current in higher frequency bands. The first to fourth dipole arms meet in the central region of the radiating element, and when viewed from the front, the first dipole arm extends upward from the central region, the third dipole arm extends downward from the central region, and both the second and fourth dipole arms extend to a first side of the central region.

10. The dual-polarized radiating element of claim 9, wherein each of the first to fourth dipole arms comprises a conductive ring.

11. The dual-polarized radiating element of claim 10, wherein each conductive ring has a first segment and a spaced-apart opposing second segment, and wherein the first segment of the first dipole arm is substantially collinear with the first segment of the third dipole arm.

12. The dual-polarized radiating element according to claim 10 or 11, wherein each conductive ring has a first segment and a spaced-apart opposing second segment, and wherein the first segment of the second dipole arm is substantially parallel to the first segment of the fourth dipole arm.

13. The dual-polarized radiating element according to any one of claims 9-11, wherein each of the first dipole arm to the fourth dipole arm comprises a plurality of spaced-apart conductive members connected to each other via respective inductance trace segments.

14. The dual-polarized radiating element according to any one of claims 9-11, wherein the first dipole arm is configured to have an average current direction extending along a first direction, and the second dipole arm is configured to have an average current direction extending along a second direction, wherein the first direction and the second direction intersect to define an obtuse angle.

15. The dual-polarized radiating element according to any one of claims 9-11, wherein the first dipole radiator is configured to emit RF radiation with a tilt polarization of -45°, and the second dipole radiator is configured to emit RF radiation with a tilt polarization of +45°.

16. A dual-polarized radiating element for a base station antenna, comprising: feed handle; A dipole radiator printed circuit board is mounted on the front end of the feed handle. The dipole radiator printed circuit board includes a first dipole arm to a fourth dipole arm, which extend from a central region. In the central region, the feed handle is electrically connected to the dipole radiator printed circuit board. When viewed from the front, the first dipole arm generally extends upward from the central region, the third dipole arm generally extends downward from the central region, and both the second and fourth dipole arms generally extend to a first side of the central region. The first dipole arm and the third dipole arm form a first dipole radiator, and the second dipole arm and the fourth dipole arm form a second dipole radiator.

17. The dual-polarized radiating element of claim 16, wherein each of the first to fourth dipole arms comprises a conductive ring.

18. The dual-polarized radiating element of claim 17, wherein each conductive ring has a first segment and an opposing second segment, and wherein the first segment of the second dipole arm extends substantially parallel to the first segment of the fourth dipole arm.

19. The dual-polarized radiating element of claim 17, wherein the first segment of the first dipole arm and the first segment of the third dipole arm extend substantially collinearly.

20. The dual-polarized radiating element of claim 17, wherein the first dipole radiator is configured to emit RF radiation with a tilt polarization of -45°, and the second dipole radiator is configured to emit RF radiation with a tilt polarization of +45°.

21. The dual-polarized radiating element according to any one of claims 16-20, wherein the first dipole arm is configured to have an average current direction extending along a first direction, and the second dipole arm is configured to have an average current direction extending along a second direction, wherein the first direction and the second direction intersect to define a first obtuse angle.

22. The dual-polarized radiating element of claim 21, wherein the third dipole arm is configured to have an average current direction extending along a third direction, and the fourth dipole arm is configured to have an average current direction extending along a fourth direction, wherein the third direction and the fourth direction intersect to define a second obtuse angle.

23. The dual-polarized radiating element according to claim 22, wherein the first obtuse angle is equal to the second obtuse angle.

24. The dual-polarized radiating element according to any one of claims 16-20, wherein at least one of the first dipole arm and the second dipole arm comprises a plurality of spaced-apart conductive members connected to each other via respective inductance trace segments.

25. A dual-polarized radiating element for a base station antenna, comprising: feed handle; A first dipole radiator is installed on the front end of the feed handle, the first dipole radiator including a first dipole arm and a second dipole arm; A second dipole radiator is installed on the front end of the feed handle, the second dipole radiator including a third dipole arm and a fourth dipole arm; The first dipole arm and the third dipole arm each include a first segment and a spaced-apart second segment, wherein the first segment of the first dipole arm and the first segment of the third dipole arm are collinear. The first to fourth dipole arms meet in the central region of the radiating element, and when viewed from the front, the first dipole arm extends upward from the central region, the third dipole arm extends downward from the central region, and both the second and fourth dipole arms extend to a first side of the central region.

26. The dual-polarized radiating element of claim 25, wherein the second dipole arm and the fourth dipole arm each comprise a first segment and a spaced-apart second segment, wherein the first segment of the second dipole arm is parallel to the first segment of the fourth dipole arm.

27. The dual-polarized radiating element of claim 26, wherein the first segment of the first dipole arm is not collinear with the first segment of the fourth dipole arm.

28. The dual-polarized radiating element of claim 27, wherein the first dipole radiator is configured to emit RF radiation with a tilt polarization of -45°, and the second dipole radiator is configured to emit RF radiation with a tilt polarization of +45°.

29. A base station antenna, the base station antenna comprising: Reflector; A first array, the first array comprising a first vertically extending column of lower frequency band radiating elements, the lower frequency band radiating elements being mounted to extend forward from the reflector; A second array, the second array comprising a second vertically extending column of lower frequency band radiating elements, the lower frequency band radiating elements being mounted to extend forward from the reflector; A multi-column array of higher-frequency radiating elements located between the first array and the second array. The first array and the second array each include at least one radiating element of a first type, which is horizontally adjacent to the multi-column array of the higher-frequency radiating element, and at least one radiating element of a second type, which is not horizontally adjacent to the multi-column array of the higher-frequency radiating element, wherein the first type is different from the second type. At least one radiating element in the first array of lower frequency band radiating elements includes a stealthy dipole arm with an inductive element configured to suppress current in the operating frequency band of the multi-column array. The at least one radiating element in the first array of lower frequency band radiating elements includes a first dipole arm to a fourth dipole arm, the first dipole arm to the fourth dipole arm meeting in a central region such that, when viewed from the front, the first dipole arm extends upward from the central region, the third dipole arm extends downward from the central region, and both the second dipole arm and the fourth dipole arm extend to a first side of the central region; the first dipole arm and the third dipole arm form a first dipole radiator, and the second dipole arm and the fourth dipole arm form a second dipole radiator.

30. The base station antenna of claim 29, wherein a first array of lower frequency band radiating elements extends along a first side of the reflector, and a second array of lower frequency band radiating elements extends along a second side of the reflector.

31. The base station antenna according to claim 29, wherein at least one of the first to fourth dipole arms is in the form of a conductive ring.

32. The base station antenna of claim 29 or 31, wherein the second type of radiating element comprises a first dipole radiator and a second dipole radiator, the first dipole radiator being configured to emit RF radiation with a tilt polarization of -45°, and the second dipole radiator being configured to emit RF radiation with a tilt polarization of +45°.

33. The base station antenna according to claim 29 or 31, wherein the second type of radiating element comprises a cross-dipole radiating element, the cross-dipole radiating element comprising a pair of dipole radiators, each of the pair of dipole radiators comprising two collinear dipole arms.

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