Base station antenna feed plate comprising RF transmission lines with different transmission speeds

Abstract

Base station antenna feed panels are provided. A base station antenna feed panel includes a phase shifter and a hybrid radio frequency transmission line coupled to the phase shifter. The hybrid radio frequency transmission line includes a coplanar waveguide and a microstrip line. Related base station antennas are also provided.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 126,215, filed December 16, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to wireless communication systems, and more specifically to radio frequency (“RF”) transmission lines on base station antenna feed boards. Background Technology

[0004] Base station antennas for wireless communication systems are used to transmit RF signals to and receive RF signals from fixed and mobile users of cellular communication services. Base station antennas typically comprise a linear or two-dimensional array of radiating elements (e.g., crossed dipoles or patch radiating elements). To change the downtilt angle of the antenna beam generated by the linear array of radiating elements, a phase taper can be applied to the radiating elements. Such a phase taper can be applied by adjusting the settings of an adjustable phase shifter positioned along the RF transmission path (including RF transmission lines) between the radio equipment and the individual radiating elements of the base station antenna.

[0005] One known type of phase shifter is the electromechanical rotating "wiper" phase shifter, which includes a main printed circuit board (PCB) and a "wiper" PCB that can rotate above the main PCB. Such a wiper-type phase shifter typically splits the input RF signal received at the main PCB into multiple sub-components, and then capacitively couples at least some of these sub-components to the wiper PCB. These sub-components of the RF signal can be capacitively coupled back to the main PCB from the wiper PCB along multiple arcuate traces, where each arc has a different radius. Each end of each arcuate trace can be connected to a radiating element or a subgroup of radiating elements. By physically rotating the wiper PCB above the main PCB, the position where the sub-components of the RF signal are capacitively coupled back to the main PCB can be changed, thereby changing the path length traversed by the sub-components of the RF signal as they travel from the radio equipment to the radiating element. These changes in path length result in phase changes in the corresponding sub-components of the RF signal, and because the arcs have different radii, the phase changes experienced along each path will be different.

[0006] Typically, phase taper is applied by applying positive phase shifts of various magnitudes (e.g., +Xº, +2Xº, and +3Xº) to some sub-components of an RF signal and negative phase shifts of the same magnitudes (e.g., -Xº, -2Xº, and -3Xº) to other sub-components of the RF signal. Therefore, the aforementioned rotating broom-type phase shifter can be used to apply phase taper to sub-components of an RF signal transmitted through corresponding radiating elements (or subgroups of radiating elements). Exemplary phase shifters of this type are discussed in U.S. Patent No. 7,907,096, the disclosure of which is hereby incorporated herein by reference in its entirety. Typically, an actuator is used to move the broom PCB, the actuator comprising a DC (“DC”) motor connected to the broom PCB via a mechanical linkage. These actuators are often referred to as “RET” actuators because they are used to apply a remote electrical downtilt. RET actuators can also apply downtilt to non-rotating phase shifters, such as adjustable U-shaped waveguide joints (trombones) or sliding medium phase shifters.

[0007] The feed board (e.g., PCB) of a base station antenna can be shared by various components, including phase shifters, radiating elements, and RF transmission lines. Feed boards are typically manufactured as small as possible to reduce costs. As a result, feed boards can be relatively crowded. Furthermore, to ensure that the RF transmission lines extending on the feed board between the phase shifter output and the radiating element have a matched phase delay, the RF transmission lines can be long, meandering lines, further exacerbating the crowding of the feed board. Consequently, RF transmission lines can be very close to each other, which can lead to high mutual coupling. Summary of the Invention

[0008] According to an embodiment of the present invention, a base station antenna may include a PCB having a phase shifter and a plurality of RF transmission lines coupled to the phase shifter. Furthermore, the base station antenna may include a plurality of radiating elements on the PCB and coupled to the RF transmission lines. A first RF transmission line may include a coplanar waveguide (“CPW”) coupled to a first radiating element. A second radiating element may be coupled to a second RF transmission line, the second RF transmission line being shorter than the first RF transmission line.

[0009] In some embodiments, the first radiating element of the radiating elements may be farther away from the phase shifter than the second radiating element of the radiating elements.

[0010] According to some embodiments, the second RF transmission line in the RF transmission line may include a microstrip line and may not have any CPW. Furthermore, the first RF transmission line in the RF transmission line may include at least one microstrip line. The at least one microstrip line of the first RF transmission line in the RF transmission line may include, for example: a first microstrip line coupling the CPW to the phase shifter; and a second microstrip line coupling the CPW to a first radiating element in the radiating element.

[0011] In some embodiments, the CPW may include three coplanar conductive lines on a first surface of the PCB. The CPW may also include ground vias that couple two of the conductive lines to a ground plane on a second surface of the PCB opposite the first surface. For example, the first and second rows of ground vias may be located on a first and a second portion of the ground plane, respectively. Furthermore, the ground plane may have an opening between the first and second portions of the ground plane.

[0012] According to some embodiments, the base station antenna may include a reflector facing the ground plane. The reflector may have an opening formed by the overlapping of intermediate conductive lines among the conductive lines.

[0013] In some embodiments, the CPW may be the first CPW among a plurality of CPWs of the PCB, and the phase shifter may be the first phase shifter among a plurality of phase shifters of the PCB respectively coupled to the CPW.

[0014] According to some embodiments, the CPW can also be coupled to a third radiating element in the radiating element. Furthermore, the second RF transmission line in the RF transmission line can also be coupled to a fourth radiating element in the radiating element.

[0015] According to some embodiments, the base station antenna may include a reflector having an opening. The base station antenna may include a PCB on the reflector and having a phase shifter and a plurality of RF transmission lines coupled to the phase shifter. Furthermore, the base station antenna may include a plurality of radiating elements on the PCB and coupled to the RF transmission lines. A first RF transmission line may be coupled to a first radiating element and may include a CPW overlapping the opening of the reflector.

[0016] In some embodiments, the first RF transmission line in the RF transmission line may include a microstrip line coupled to the CPW. For example, the CPW may be coupled to the phase shifter by the microstrip line. As another example, the CPW may be coupled to a first radiating element in the radiating element by the microstrip line. Furthermore, the microstrip line may be the first microstrip line of a pair of microstrip lines in the first RF transmission line, and the CPW may be coupled between the pair of microstrip lines.

[0017] According to some embodiments, a base station antenna feed board may include a phase shifter and a hybrid RF transmission line coupled to the phase shifter and comprising CPW and microstrip lines. The hybrid RF transmission line may be longer than any non-CPW RF transmission line of the base station antenna feed board.

[0018] In some embodiments, the CPW can be coupled to the phase shifter via the microstrip line.

[0019] According to some embodiments, the CPW may include two external conductive lines on a first surface of the base station antenna feed board. The CPW may also include a central conductive line coupled to the microstrip line and located between the two external conductive lines on the first surface of the base station antenna feed board. Furthermore, the CPW may include a ground via coupling the two external conductive lines to a ground plane on a second surface of the base station antenna feed board opposite the first surface.

[0020] In some embodiments, the base station antenna feed board may include a second layer of conductive lines on a second surface of the base station antenna feed board and overlapping the central conductive line. The base station antenna feed board may also include a non-grounded via coupling the central conductive line and the second layer of conductive lines to each other. Furthermore, the ground plane may have a first portion and a second portion, respectively, overlapped by the two outer conductive lines. The ground plane may also have an opening separating the second layer of conductive lines from the first and second portions of the ground plane.

[0021] According to some embodiments, a base station antenna feed board may include a phase shifter and a first RF transmission line and a second RF transmission line, the first RF transmission line and the second RF transmission line being coupled to the phase shifter and having a first RF wave velocity and a second RF wave velocity, respectively. The second RF wave velocity may be slower than the first RF wave velocity.

[0022] In some embodiments, the first RF transmission line may be longer than the second RF transmission line. Furthermore, the first RF transmission line may include a CPW (Concurrent Wire Wrapper), and the second RF transmission line may be a non-CPW RF transmission line.

[0023] According to some embodiments, the first RF transmission line may include a conductive line separated from the ground plane of the base station antenna feed plate by air. Furthermore, the base station antenna feed plate may include a reflector, and the substrate of the base station antenna feed plate may be located between the ground plane and the reflector.

[0024] In some embodiments, the first RF transmission line may include a coaxial RF transmission line having a shield and a center conductor separated from the shield by air. Attached Figure Description

[0025] Figure 1 This is a front perspective view of a base station antenna according to an embodiment of the present invention.

[0026] Figure 2A This is a front view of a base station antenna feed board according to an embodiment of the present invention.

[0027] Figure 2B and 2C for Figure 2A A magnified front view of the power supply board.

[0028] Figure 3A for Figure 2A Front view of the feed plate on the reflector.

[0029] Figure 3B for Figure 3A Front view of the reflector.

[0030] Figure 3C for Figure 2A Rear view of the grounding plane of the feeder board.

[0031] Figure 3D-3F For along Figure 2A A schematic cross-sectional view of the different conductive lines of the CPW.

[0032] Figure 4 This is a front view of an antenna assembly including multiple feed plates according to an embodiment of the present invention.

[0033] Figure 5 This is a schematic cross-sectional view along a portion of an RF transmission line including an air-microstrip line, according to another embodiment of the present invention.

[0034] Figure 6 This is a schematic cross-sectional view along a portion of an RF transmission line including an air-coaxial line, according to another embodiment of the present invention.

[0035] Figure 7 For along Figure 2A A cross-sectional view of the CPW in the width direction. Detailed Implementation

[0036] According to embodiments of the present invention, the RF transmission lines on the base station antenna feed board may include RF transmission lines with different transmission speeds. For example, although the RF transmission lines on a conventional base station antenna feed board may all be microstrip lines only, at least one RF transmission line according to embodiments of the present invention may include different types of RF transmission lines, such as CPW RF transmission lines.

[0037] As discussed above, a linear array of a base station antenna including remote electronic downtilt capability includes a phase shifter inserted between the RF input and the linear array. The phase shifter splits the RF signal received at the RF input into multiple sub-components output at the corresponding outputs of the phase shifter. Each output of the phase shifter is connected by an RF transmission line to one or more radiating elements of the linear array, such that all radiating elements in the linear array are connected to the phase shifter. Typically, the RF transmission lines are designed such that the phase shift between each output of the phase shifter and its associated radiating element is the same. Therefore, any phase shift applied to downtilt the antenna bundle formed by the linear array is applied to an adjustable portion of the phase shifter. With this design, all RF transmission lines extending between the outputs of the phase shifter and the radiating elements of the linear array can have the same length. In other cases, the transmission lines can be designed to apply a fixed amount of downtilt to the antenna bundle, and the adjustable portion of the phase shifter can be used to increase or decrease the amount of downtilt from the fixed downtilt. In this case, the RF transmission lines extending from the outputs of the phase shifter to multiple sets of one or more radiating elements of the linear array can have different lengths, and the length difference can be set based on the desired amount of fixed downtilt.

[0038] In most base station antennas, a phase shifter is mounted behind the antenna reflector and connected to a feed board via a coaxial cable. The length of the coaxial cable can be selected to maintain a desired phase relationship between each output of the phase shifter and its associated radiating element. When the phase shifter is implemented on the feed board, the desired phase relationship must be achieved by setting each RF transmission line on the feed board to have a desired length (e.g., all RF transmission lines have the same length). Therefore, the length of these transmission lines is set by the distance from the phase shifter to the farthest radiating element in the linear array. For example, if all RF transmission lines have the same phase delay, all RF transmission lines would be designed to have the same length, where this length is set by the distance between the phase shifter and the radiating element farthest from the phase shifter. As mentioned above, this typically requires the RF transmission lines extending between the phase shifter and the nearest radiating element to be severely bent to achieve the desired length, resulting in a crowded feed board with RF transmission lines closely spaced together. This leads to increased mutual coupling between the RF transmission lines.

[0039] The propagation speed of an RF signal within an RF transmission line can vary depending on the type of RF transmission line used. In particular, RF signals can propagate faster in RF transmission lines with better shielding and / or lower dielectric constants. For example, RF signals propagate faster in CPW RF transmission lines than in microstrip RF transmission lines. Therefore, by using CPW RF transmission lines to couple a phase shifter on the feed board to the farthest radiating element on the feed board, the total phase shift experienced by the RF signal across the CPW RF transmission line can be reduced. Consequently, the length of other (e.g., microstrip) RF transmission lines on the feed board can be reduced, as these microstrip RF transmission lines now have to induce less phase shift. These shortened microstrip RF transmission lines will exhibit lower insertion loss than conventionally long RF transmission lines. Furthermore, since shorter RF transmission lines occupy less space on the feed board than conventionally long RF transmission lines, the distance between RF transmission lines can be greater, thereby reducing mutual coupling between RF transmission lines.

[0040] Figure 1 This is a front perspective view of a base station antenna 100 according to an embodiment of the present invention. Antenna 100 can be, for example, a cellular base station antenna at a macrocell base station. However, it will be appreciated that the techniques disclosed herein can also be applied to other base station antennas, such as small cell base station antennas. Figure 1 As shown, antenna 100 is an elongated structure and has a generally rectangular shape. Antenna 100 includes an radome 110. In some embodiments, antenna 100 also includes a top cover 120 and / or a bottom cover 130. Bottom cover 130 may include a plurality of RF connectors 140 mounted therein. Connectors 140 may also be referred to herein as “ports”, however, the connectors are not limited to being located on bottom cover 130. Instead, one or more of connectors 140 may be disposed, for example, on the rear (i.e., back) side of antenna 100. Antenna 100 is generally mounted in a vertical configuration (i.e., the long side of antenna 100 extends along a vertical axis L relative to the ground). Connectors 140 can be mounted via one or more feed plates 200 ( Figure 2A and 4 Coupled to each group of radiating elements 230 ( Figure 2A ).

[0041] Figure 2A This is a front view of a base station antenna feed board 200 according to an embodiment of the present invention. In some embodiments, the feed board 200 may be a PCB, the PCB including a substrate 201 and a plurality of RF transmission lines 220 on the substrate 201. For example, the substrate 201 may be a non-conductive (e.g., dielectric) substrate that includes a front surface 200F having conductive (e.g., copper) traces thereon having the transmission lines 220.

[0042] Multiple phase shifters 210 and multiple radiating elements 230 may also be located on the front surface 200F of the substrate 201. Figure 2A The PCB of each phase shifter 210 is omitted to better illustrate the feed board 200. Each phase shifter 210 may be coupled to a plurality of transmission lines 220, each of which is coupled to at least one radiating element 230. Figure 2A Only the installation location of the radiating element is shown, and it is marked with reference numeral 230; it will be understood that the radiating element 230 will be installed... Figure 2A (Each of the radiating element mounting locations shown in the diagram). In some embodiments, each phase shifter 210 may have three RF outputs coupled to three corresponding RF transmission lines 220, and each RF transmission line 220 may be coupled to two radiating elements 230. For example, the feed board 200 may have six radiating elements 230-1 to 230-6, and two phase shifters 210-1 and 210-2, each coupled to all radiating elements 230. Two phase shifters 210-1 and 210-2 are provided to feed RF signals having a first polarization and a second polarization to the radiating elements 230.

[0043] Specifically, phase shifter 210-1 can be coupled (i) to radiating elements 230-1 and 230-5 via transmission line 220-1, (ii) to radiating elements 230-2 and 230-6 via transmission line 220-2, and (iii) to radiating elements 230-3 and 230-4 via transmission line 220-3. Furthermore, phase shifter 210-2 can be coupled (a) to radiating elements 230-2 and 230-6 via transmission line 220-4, (b) to radiating elements 230-1 and 230-5 via transmission line 220-5, and (c) to radiating elements 230-3 and 230-4 via transmission line 220-6. Radiating elements 230 can be, for example, dual-polarized cross-dipole radiating elements, and phase shifters 210-1 and 210-2 can be coupled to the corresponding dipole of each radiating element 230 (which may have the corresponding polarization). As used herein, the term “coupling” refers to electrical coupling / connection, and in some embodiments, it may also refer to physical coupling / connection.

[0044] Some of the transmission lines 220 may have a different type than the others. For example, transmission lines 220-1 and 220-4 may include corresponding CPWs C1 and C2 coupled to phase shifters 210-1 and 210-2, respectively, while transmission lines 220-2, 220-3, 220-5, and 220-6 may be non-CPW transmission lines. Specifically, in some embodiments, transmission lines 220-1 and 220-4 may be hybrid RF transmission lines that respectively include CPWs C1 and C2 and each also includes at least one microstrip line. Figure 2AAs shown, CPW C1 is coupled between a pair of microstrip lines M1 and M2 of transmission line 220-1. Similarly, transmission line 220-4 is shown with a pair of microstrip lines M5 and M6, with CPW C2 coupled between them. On the other hand, transmission lines 220-2, 220-3, 220-5, and 220-6 are shown with microstrip lines M4, M3, M7, and M8, respectively, without any CPW.

[0045] In some embodiments, the microstrip line M2 can be shortened, and the CPW C1 can be extended to a greater length than... Figure 2A The radiating elements 230-1 and 230-5 are shown closer to the radiating elements. However, using more CPW C1 in this way may require extending the reflector 310 ( Figure 3B Opening 320-1 in ) Figure 3B This corresponds to the extended CPW C1 length, which brings the opening 320-1 closer to the radiating elements 230-1 and 230-5, and may negatively impact their performance.

[0046] Non-CPW transmission lines 220-2, 220-3, 220-5, and 220-6 are shorter than transmission lines 220-1 and 220-4, which include CPW C1 and C2. Therefore, transmission lines 220-1 and 220-4 are the longest transmission lines on feed board 200. By including CPW C1 and C2 in the longest transmission lines 220-1 and 220-4, the total electrical length of transmission lines 220-1 and 220-4 can be shorter than when transmission lines 220-1 and 220-4 are non-CPW (e.g., microstrip only) transmission lines. Therefore, the physical lengths of the other transmission lines 220-2, 220-3, 220-5, and 220-6 can be shorter than when transmission lines 220-1 and 220-4 are non-CPW transmission lines. Specifically, CPW C1 and C2 allow the relatively short transmission lines 220-2, 220-3, 220-5 and 220-6 to match the phase (electrical length) of the longest transmission lines 220-1 and 220-4 (or to have the desired relationship between the phase shifts of different RF transmission lines).

[0047] Figure 2B and 2C yes Figure 2A A magnified front view of the feeder board 200. Specifically, Figure 2B and 2C Enlarged views of opposite ends of the CPW C1 on the feed board 200 are shown respectively. (Reference) Figure 2A and 2BCPW C1 can be coupled to phase shifter 210-1 via microstrip line M1. Furthermore, CPW C1 includes three coplanar conductive lines 220-A, 220-B, and 220-C on the front surface 200F of feed plate 200. Conductive line 220-C is the intermediate / center conductive line between the two grounded external conductive lines 220-A and 220-B. (As...) Figure 2B As shown, the intermediate / center conductive line 220-C can be physically and electrically coupled to the microstrip line M1.

[0048] In some embodiments, the CPW C1 may have a grounding via GV. For example, the grounding via GV can couple two external conductive lines 220-A and 220-B to the rear surface 200B of the feed board 200. Figure 3D Ground plane 330 on ) Figure 3C Furthermore, in some embodiments, the intermediate / center conductive line 220-C may also have through-holes (e.g., electroplated through-holes) PT. For example, a row of through-holes PT can be coupled to the intermediate / center conductive line 220-C and the second layer conductive line 350. Figure 3C The second layer of conductive wire is formed by opening 340-1 in the grounding plane 330 ( Figure 3C ) and adjacent portions 330-A and 330-B of ground plane 330 ( Figure 3C Electrical isolation. Therefore, the row of vias PT coupled to the intermediate / center conductor 220-C may not be grounded. Specifically, this row of vias PT can be used to increase the capacitance between the intermediate / center conductor 220-C and the two outer conductors 220-A and 220-B. In some embodiments, this row of vias PT may penetrate the intermediate / center conductor 220-C.

[0049] The center / center conductor 220-C can be an internal CPW trace, and the two outer conductors 220-A and 220-B can be CPW ground traces. In the CPW transmission line C1, signals can be transmitted between the inner trace 220-C and the CPW ground traces 220-A and 220-B. Because CPW C1 includes the use of through-hole GV / PT (… Figure 2B Instead of a single layer of three traces (220-A, 220-B, and 220-C) without vias, the inner trace 220-C has a relatively large capacitance to ground. This allows for a larger gap for 50-ohm transmission lines (e.g., between conductive line 220-C and conductive lines 220-A and 220-B), a gap that would be impossible to achieve using a single copper layer (three traces without vias). Therefore, by using CPW C1, the fabrication of PCB200 can be enhanced and the risk of short circuits can be reduced. Furthermore, this CPW C1 design provides lower losses and a shorter electrical length for the same physical length.

[0050] refer to Figure 2A and 2C CPW C1 can be coupled to radiating elements 230-1 and 230-5 via microstrip line M2. For example... Figure 2C As shown, the center / center conductive line 220-C of CPW C1 can be physically and electrically coupled to microstrip line M2. Radiating element 230-1 is the radiating element 230 furthest from phase shifter 210-1. Therefore, the transmission line 220-1, including (i) CPW C1 and (ii) at least one microstrip line (e.g., microstrip line M2 and / or microstrip line M1), is the longest transmission line 220 coupled to phase shifter 210-1.

[0051] Multi-row through-hole GV / PT ( Figure 2B The ground via GV can be coupled to CPW C1. For example, the first row GV-R1 of the ground via GV can be coupled to the external conductive line 220-A, and the second row GV-R2 of the ground via GV can be coupled to the external conductive line 220-B. In some embodiments, rows GV-R1 and GV-R2 can extend substantially the entire length of CPW C1. For example, rows GV-R1 and GV-R2, together with CPW C1 itself, can extend to approximately 125-144 mm. The microstrip line M1 is shorter than CPW C1. Furthermore, in some embodiments, the microstrip line M2 can be shorter than CPW C1.

[0052] Figure 3A for Figure 2A The feed plate 200 is shown as a front view on the reflector 310. For simplicity, the radiating element 230 and its corresponding mounting location are shown below. Figure 2A (Omitted from view) Figure 3AThe diagram shows (i) the opposite ends a and b of transmission line 220-1, (ii) the opposite ends c and d of transmission line 220-2, and (iii) the opposite ends e and f of transmission line 220-3. Ends a, c, and e are located at (or adjacent to) the corresponding output nodes of phase shifter 210-1. Ends b, d, and f are located at (or adjacent to) the corresponding radiating elements 230. The distance between opposite ends a and b can be fixed, and said distance is the longest distance from phase shifter 210-1 to any radiating element 230. Furthermore, transmission lines 220-2 and 220-3 between the respective pairs of opposite ends c and d and e and f may need, for example, to have the same phase (electrical length) as transmission line 220-1 between opposite ends a and b. Therefore, by including a CPW C1 with an electrical length shorter than that of a corresponding microstrip line of the same physical length in transmission line 220-1, the conductive traces of transmission lines 220-2 and 220-3 can be shorter (e.g., with less meandering) than the conductive traces required for the electrical length of a conventional microstrip-only transmission line that matches the entire distance between the matching ends a and b. For example, the conductive traces of transmission lines 220-2 and 220-3 can be no more than 83% of the length of the conductive trace required for the electrical length of such a conventional microstrip-only transmission line between the matching ends a and b.

[0053] Figure 3B for Figure 3A A front view of reflector 310, wherein the feed plate 200 is omitted from the view. (See image) Figure 3B As shown, the reflector 310 may include at least one opening 320. For example, two spaced-apart openings 320-1 and 320-2 may be corresponding slots / cutouts in the reflector 310, which may be a conductive (e.g., metallic) reflector. Figure 3B It is also shown that the corresponding portions of openings 320-1 and 320-2 can extend parallel to each other, and the end of opening 320-1 may not be aligned with the end of opening 320-2. Openings 320-1 and 320-2 may correspond to CPW C1 and C2 respectively. Figure 2A Specifically, CPW C1 and C2 may each include an intermediate / center conductive line 220-C that overlaps with openings 320-1 and 320-2, respectively. Figure 2B Because of openings 320-1 and 320-2, the via PT along the signal trace (i.e., along the middle / center conductive line 220-C) is not short-circuited to the reflector 310.

[0054] Furthermore, in some embodiments, each opening 320 may be wider than the middle / center conductive line 220-C. For example, opening 320-1 may extend from a position below the inner part of row GV-R1 ( Figure 2C ) to the position below the inner part of line GV-R2 ( Figure 2C).

[0055] Figure 3C for Figure 2A A rear view of the grounding plane 330 of the feeder board 200. The grounding plane 330 may have at least one opening 340. For example, as Figure 3C As shown, the ground plane 330 may have two spaced-apart openings 340-1 and 340-2. In some embodiments, each opening 340 extends continuously around a second layer of conductive wire 350 coplanar with the ground plane 330. Therefore, each opening 340 may be larger (e.g., wider and longer) than each of the conductive wire 350 and the intermediate / center conductive wire 220-C overlapping the conductive wire 350. Figure 3D Therefore, opening 340 and conductive line 350 may not serve as part of ground plane 330. Instead, opening 340 can electrically isolate conductive line 350 (and the intermediate / center conductive line 220-C coupled thereto) from adjacent portions 330-A and 330-B of ground plane 330 in which opening 340 extends.

[0056] In some embodiments, portions 330-A and 330-B separated by the opening 340-1 therebetween can be formed by overlapping conductive lines 220-A and 220-B of CPWC1, respectively. Figure 2B Because conductive lines 220-C and 350 can both be hot wires / traces, they are coupled to each other and electrically isolated from the ground plane 330 by the opening 340, so transmission line 220-1 can have a relatively short electrical length for its physical length. This structure also results in lower losses and allows for a relatively large gap between conductive lines 220-C and conductive lines 220-A and 220-B.

[0057] Figure 3D-3F For along Figure 2A A schematic cross-sectional view showing the longitudinal direction decomposition of different conductive lines in CPW C1. Figure 3D The middle / center conductive line 220-C along CPW C1 is shown. Figure 2B A cross-sectional view of ( ). For example... Figure 3D As shown, conductive line 220-C overlaps with opening 320-1 of reflector 310. Conductive line 220-C also overlaps with a second layer of conductive line 350, which overlaps with adjacent portions 330-A and 330-B of ground plane 330. Figure 3C The conductive lines 220-C and 350 are coplanar and electrically isolated from the adjacent portions. In some embodiments, the conductive line 350 may be a copper trace on the back surface 200B of the substrate 201. Furthermore, a via PT in the substrate 201 may connect the conductive lines 220-C and 350 to each other.

[0058] Figure 3DThe ground plane 330 is also shown on the substrate 201 of the reflector 310 and the feed plate 200. Figure 2A )between. Figure 3D It is also shown that the substrate 201 has a back surface 200B opposite its front surface 200F. Therefore, the reflector 310 faces the ground plane 330, which faces the back surface 200B of the substrate 201. Although for the sake of simplicity, from... Figure 3D The dielectric layer (e.g., gasket) is omitted in the view, but the dielectric layer may be between the ground plane 330 and the reflector 310.

[0059] Figure 3E The external conductive line 220-A along CPW C1 is shown. Figure 2C A cross-sectional view of ( ). For example... Figure 3E As shown, conductive line 220-A overlaps with a portion 330-A of ground plane 330. Conductive line 220-A also overlaps with row GV-R1 of ground via GV penetrating substrate 201. Figure 2B and 2C The line GV-R1 overlaps with and is electrically connected to the row. The row GV-R1 overlaps with and is also coupled to a portion 330-A of the ground plane 330. Therefore, the conductive line 220-A is coupled from the row GV-R1 to a portion 330-A of the ground plane 330. Furthermore, the ground plane 330 may be coupled to / grounded to the reflector 310.

[0060] Figure 3F The external conductive line 220-B along CPW C1 is shown. Figure 2C A cross-sectional view of ( ). For example... Figure 3F As shown, conductive line 220-B overlaps with a portion 330-B of ground plane 330. Conductive line 220-B also overlaps with row GV-R2 of ground via GV penetrating substrate 201. Figure 2B and 2C The line GV-R2 overlaps with and is coupled to a portion 330-B of the ground plane 330. Therefore, the conductive line 220-B is coupled from the line GV-R2 to a portion 330-B of the ground plane 330.

[0061] To simplify the explanation, only in Figure 3E and 3F Rows GV-R1 and GV-R2 are shown in substrate 201. However, in some embodiments, rows GV-R1 and GV-R2 may also extend through conductive lines 220-A and 220-B, respectively.

[0062] Figure 4This is a front view of an antenna assembly 400 including multiple feed plates 200 according to an embodiment of the present invention. The feed plates 200 of the assembly 400 may all share the same reflector 310. For example, the assembly 400 may include two rows of feed plates 200. Figure 4 As shown, the first row includes eight feed plates 200-1 to 200-8 on reflector 310, and the second row includes another eight feed plates 200-9 to 200-16 on reflector 310. Feed plates 200 can be mounted on the front side of reflector 310. Component 400 can be part of antenna 100. Figure 1 Therefore, there are a total of sixteen feed plates 200-1 to 200-16. However, in antenna assemblies of other embodiments, more (e.g., at least eighteen) or fewer (e.g., one, two, four, six, eight, ten, twelve, or fourteen) feed plates 200 may be located on the reflector 310. Furthermore, each feed plate 200 of assembly 400 may include CPW C1 (… Figure 2A ) and / or CPW C2 ( Figure 2A ).

[0063] Figure 5 This is a schematic cross-sectional view of a portion (e.g., an end portion) of an RF transmission line 220-1' including an air-microstrip line, according to another embodiment of the present invention. Transmission line 220-1' is a non-CPW transmission line. Specifically, non-CPW transmission line 220-1' includes CPW C1 (… Figure 2A Transmission line 220-1 ( Figure 2A An alternative to ), transmission line 220-1' can therefore be coupled to phase shifter 210-1. Figure 2A ) and radiating elements 230-1 and 230-5 ( Figure 2A ), and may have opposite ends a and b ( Figure 3A The air-microstrip line of transmission line 220-1' includes a conductive line M9 (e.g., a thin strip of metal), wherein air 550 is between a portion of ground plane 330 and a portion of conductive line M9. Furthermore, ground plane 330 may be located within a feed plate 200 including transmission line 220-1'. Figure 4 On the front surface 200F of the substrate 201. Figure 5 The cross-section shown is cut along the longitudinal direction / dimension of the substrate 201 and the transmission line 220-1'.

[0064] Figure 6 This is a schematic cross-sectional view of a portion (e.g., an end portion) of an RF transmission line 220-1'' including an air-coaxial line, according to another embodiment of the present invention. Transmission line 220-1'' and transmission line 220-1' ( Figure 5 Similar to transmission line 220-1 ( ) Figure 2A A non-CPW alternative. Therefore, transmission line 220-1'' can be coupled to phase shifter 210-1 ( Figure 2A ) and radiating elements 230-1 and 230-5 ( Figure 2A ), and may have opposite ends a and b ( Figure 3A The air-coaxial cable of transmission line 220-1'' includes a central conductor 610 primarily surrounded by air 620. A plurality of spaced-apart dielectric spacers 625 may also surround portions of the central conductor 610 to provide structural support. Furthermore, the air 620 and spacers 625 may be surrounded (e.g., encircled) by a conductive shield 630 and an outer dielectric 640. Figure 6 The cross-section shown is cut along the longitudinal direction / dimension of transmission line 220-1''.

[0065] RF signals propagate faster on transmission lines 220-1, 220-1', and 220-1'' than on conventional microstrip transmission lines, and therefore can each have a shorter electrical length than a segment of a microstrip transmission line of the same physical length. For example, the CPW C1 of transmission line 220-1 can help maintain the electric field in the air above the front surface 200F ( Figure 2A This helps to shorten electrical length. Furthermore, if all transmission lines 220 in the network (e.g., on feedboard 200) are conventional microstrip transmission lines only, they can have an average insertion loss of 0.71 dB, while a transmission line network including transmission line 220-1' with CPW C1 can have a relatively low average insertion loss, such as 0.66 dB. The air-microstrip line 220-1' can also have relatively low insertion loss because air has a lower dielectric loss than other dielectrics.

[0066] Figure 7 For along Figure 2A A cross-sectional view of the CPW C1 in the width direction. In some embodiments, the width direction may be perpendicular to... Figure 3D The longitudinal direction is shown in the figure. (As shown in the figure) Figure 7 As shown, CPW C1 can be a double-layer CPW. Specifically, the conductive line 220-C of CPW C1 can overlap with the second layer of conductive line 350 of CPW C1. For example, the sidewall of conductive line 220-C can be aligned with the sidewall of conductive line 350 in the vertical direction. Furthermore, conductive lines 220-C and 350 can be coupled to each other by an ungrounded via PT, thus together serving as a combined inner trace / transmission segment of CPW C1. Therefore, the term "inner trace" can refer to conductive line 220-C and / or conductive line 350.

[0067] If the conductor 350 is instead removed from the transmission section of CPW C1, a narrower gap (e.g., a narrower opening 340-1) may be required between the inner trace and ground, which could adversely affect the PCB manufacturing process. Removing the conductor 350 can also increase losses and increase the electrical length of CPW C1 over a given physical length.

[0068] Figure 7 It is also shown that in some embodiments, the transmission section vias PT can be arranged in multiple rows. Similarly, external conductive lines 220-A and 220-B can each be coupled to multiple rows of ground vias GV.

[0069] Having a CPW C1 (according to an embodiment of the present invention) Figure 2A RF transmission line 220-1 ( Figure 2A ) base station antenna feed board 200 ( Figure 2A This offers many advantages. These advantages include allowing non-CPW transmission lines 220-2, 220-3, 220-5, and 220-6 (…). Figure 2A ) Matching the phase shift / delay of transmission line 220-1, while due to CPW C1 (and CPW C2 (of transmission line 220-4) Figure 2A The non-CPW transmission lines 220-2, 220-3, 220-5, and 220-6 offer a reduced electrical length, significantly shorter (e.g., 18 mm shorter). Because RF transmission waves propagate faster in a CPW than in a microstrip line, the phase delay of a CPW over a given length is smaller than that of a microstrip line of the same length. Therefore, the non-CPW transmission lines 220-2, 220-3, 220-5, and 220-6 can thus have less bend and increased spacing from adjacent transmission lines 220 compared to when transmission lines 220-1 and 220-4 are replaced by conventional microstrip-only transmission lines. Due to their relatively short length, the non-CPW transmission lines 220-2, 220-3, 220-5, and 220-6 can provide lower losses and lower mutual coupling.

[0070] Lower mutual coupling can increase isolation between ports. For example, the isolation between two input ports can be 5 dB better on average compared to a network with only conventional microstrip transmission lines. Furthermore, radiation pattern performance can be improved. Power distribution can also be improved because increasing the isolation between the conductive traces of transmission line 220 results in better power distribution. In some embodiments, performance (e.g., isolation performance, power distribution performance, etc.) can be varied based on tilt angle / phase tilt. For example, the worst isolation performance can be achieved at a set of outputs of phase shifter 210 ( Figure 2A The middle angle occurs in ().

[0071] As used herein, the terms “CPW” and “coplanar waveguide” can refer to any waveguide having coplanar conductive lines / traces. Therefore, these terms are not limited to CPWs using plated vias. These terms are also not limited to double-layer copper. However, CPWs incorporating such features (e.g., CPWs C1 and C2) can be advantageous. For example, a CPW using double-layer copper and plated vias connected to ground on each side and to the middle / inner trace can provide lower losses and shorter electrical lengths compared to a single-layer CPW (i.e., three traces without vias) with the same physical length. Furthermore, the large gap between the middle / inner trace and the grounded outer trace can reduce PCB manufacturing risks.

[0072] It will be appreciated that this specification describes only a few exemplary embodiments of the invention, and that the techniques described herein have applicability beyond the exemplary embodiments described above.

[0073] 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.

[0074] 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.

[0075] It will be understood that when an element is described as being “on” another element, that element may be directly on the other element, or there may be intermediate elements present. Conversely, when an element is described as being “directly on” another element, there are no intermediate elements present. It will also be understood that when an element is described as being “connected” or “coupled” to another element, that element may be directly connected or coupled to the other element, or there may be intermediate elements present. Conversely, when an element is described as being “directly connected” or “directly coupled” to another element, there are no intermediate elements present. Other terms used to describe relationships between elements should be interpreted in a similar manner (i.e., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).

[0076] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” are also intended to include the plural forms. It will also be understood that the terms “comprising,” “including,” and / or “having” as used herein mean the presence of the described 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.

[0077] 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 base station antenna, the base station antenna comprising: A printed circuit board (PCB) including a phase shifter and a plurality of radio frequency (RF) transmission lines coupled to the phase shifter; as well as Multiple radiating elements are located on the PCB and coupled to multiple RF transmission lines. The first RF transmission line of the plurality of RF transmission lines includes a coplanar waveguide (CPW) coupled to a first radiating element of the plurality of radiating elements. The second radiating element among the plurality of radiating elements is coupled to the second RF transmission line among the plurality of RF transmission lines, and the second RF transmission line among the plurality of RF transmission lines is shorter than the first RF transmission line among the plurality of RF transmission lines. The second RF transmission line among the plurality of RF transmission lines has no CPW.

2. The base station antenna according to claim 1, wherein the first radiating element of the plurality of radiating elements is farther from the phase shifter than the second radiating element of the plurality of radiating elements.

3. The base station antenna according to claim 1, wherein the second RF transmission line among the plurality of RF transmission lines comprises a microstrip line.

4. The base station antenna according to claim 1, wherein the first RF transmission line among the plurality of RF transmission lines further includes at least one microstrip line.

5. The base station antenna according to claim 4, wherein the at least one microstrip line comprises: Couple the CPW to the first microstrip line of the phase shifter; as well as The CPW is coupled to the second microstrip line of the first radiating element among the plurality of radiating elements.

6. The base station antenna according to claim 1, wherein the CPW comprises: Three coplanar conductive lines on the first surface of the PCB; as well as A grounding via, wherein the grounding via couples two of the coplanar conductive lines to a ground plane on a second surface of the PCB opposite to the first surface.

7. The base station antenna according to claim 6, The first and second rows of the grounding vias are respectively located on the first and second portions of the grounding plane, and The grounding plane includes an opening between a first portion and a second portion of the grounding plane.

8. The base station antenna according to claim 6 further includes a reflector facing the grounding plane. The reflector includes an opening that overlaps with the middle coplanar conductive line of the three coplanar conductive lines.

9. The base station antenna according to claim 1, The CPW mentioned above includes the first CPW among the plurality of CPWs of the PCB, and The phase shifter includes a first phase shifter among a plurality of phase shifters on the PCB, and the plurality of phase shifters are respectively coupled to the plurality of CPWs.

10. The base station antenna of claim 1, wherein the CPW is further coupled to a third radiating element among the plurality of radiating elements.

11. The base station antenna of claim 10, wherein the second RF transmission line of the plurality of RF transmission lines is further coupled to a fourth radiating element of the plurality of radiating elements.

12. A base station antenna feed board, the base station antenna feed board comprising: Phase shifter; First radiating element and second radiating element; A hybrid radio frequency (RF) transmission line is coupled to the phase shifter and includes a coplanar waveguide (CPW) and a microstrip line, wherein the hybrid RF transmission line is coupled between the phase shifter and the first radiating element. as well as A non-CPW RF transmission line, coupled between the phase shifter and the second radiating element. The length of the hybrid RF transmission line between the phase shifter and the first radiating element is longer than the length of the non-CPW RF transmission line between the phase shifter and the second radiating element on the base station antenna feed board.

13. The base station antenna feed board of claim 12, wherein the microstrip line is a first microstrip line coupled between the CPW and the phase shifter, and wherein the hybrid RF transmission line further includes a second microstrip line coupled between the CPW and the first radiating element.

14. The base station antenna feed board according to claim 12, wherein the CPW comprises: Two external conductive lines on the first surface of the base station antenna feed board; A central conductive line, which is coupled to the microstrip line and lies between the two outer conductive lines on the first surface of the base station antenna feed board; as well as The two external conductive lines are coupled to a grounding via on a grounding plane, which is located on a second surface of the base station antenna feed board opposite to the first surface.

15. The base station antenna feed board according to claim 14, further comprising: The second layer of conductive lines is located on the second surface of the base station antenna feed board and overlaps with the center conductive line. as well as A non-grounded via is used to couple the central conductive line and the second layer conductive line to each other. The grounding plane comprises a first portion and a second portion, respectively formed by the overlap of the two external conductive lines, and The grounding plane further includes an opening that separates the second layer of conductive wires from the first and second portions of the grounding plane.

16. A base station antenna feed board, the base station antenna feed board comprising: Phase shifter; First radiating element and second radiating element; as well as A first radio frequency (RF) transmission line and a second RF transmission line are coupled to the phase shifter and configured to have a first RF wave velocity and a second RF wave velocity, respectively, wherein the second RF wave velocity is slower than the first RF wave velocity. The first RF transmission line is coupled between the phase shifter and the first radiating element, and the second RF transmission line is coupled between the phase shifter and the second radiating element. The first RF transmission line includes a coplanar waveguide (CPW), and The second RF transmission line is a non-CPW RF transmission line.

17. The base station antenna feed board according to claim 16, wherein the first RF transmission line is longer than the second RF transmission line.

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