WO2025207640A1

WO2025207640A1 - Multilayer splitter board for cableless antenna

Info

Publication number: WO2025207640A1
Application number: PCT/US2025/021351
Authority: WO
Inventors: Evan WAYTON; Karthik JANARDHANAN; Rushil THIRANI
Original assignee: PPC Broadband Inc
Current assignee: PPC Broadband Inc
Priority date: 2024-03-25
Filing date: 2025-03-25
Publication date: 2025-10-02
Anticipated expiration: 2026-09-25

Abstract

An exemplary antenna having three reflectors triangularly disposed has two multilayer splitter boards mounted between them. Each multilayer splitter board has faces that mechanically couple to the inward-facing surface of the three reflectors. Each multilayer splitter board supports a separate frequency band. Each multilayer splitter board takes a signal input pair for each column of dipoles disposed on the reflectors and splits the signals so that one column of dipoles on each reflector radiates a single pair of signals. An advantage of the disclosed antenna is that it dramatically reduces the number of RF (Radio Frequency) cables required in manufacturing, which may reduce the weight and cost of fabrication.

Description

Multilayer Splitter Board for Cableless Antenna

BACKGROU ND OF THE INVENTION

[0001] Small cell antennas are finding increasing use in deployments such as dense urban areas, airports, stadiums, etc. These small cell antennas are typically cylindrical and have two or more reflectors, each with arrays of dipoles designed to operate in different frequency bands, whereby the reflectors are arranged to provide 360 degrees of coverage. Typical small cell antennas have three reflectors that are substantially identical and are triangularly arranged in 120 degree angular spacing.

[0002] Antenna designers are under pressure to make the small cell antenna as compact as possible, as well as to pack as many dipoles as possible within the confined space of the antenna. A problem arises from this challenge in that the reflectors must typically be arranged so that the sides with their dipoles face outwards, and the sides with power divider/splitter circuit boards that connect to the dipoles via solder joints face inwards. This causes several complications: with the solder joints hidden behind the reflectors, repairs are extremely difficult; the massive number of cables and solder connections complicate manufacturing; and the nest of cabling behind the reflectors may interfere with the mechanical motion of Remote Electrical Tilt (RET) devices. Moving the power divider/splitter circuit boards and corresponding solder joints to the front of the reflector is possible. However, doing so takes up a large amount of space on the reflector, leaving less room for the dipoles and antenna feed networks, and it still requires a massive number of cables.

[0003] Accordingly, what is needed is a small cell antenna design that vastly reduces the number of cables and which makes all board-to-board solder joints both compact and accessible from the outside of the reflectors.

SUMMARY OF THE INVENTION

[0004] An aspect of the present disclosure involves an antenna. The antenna comprises a plurality of reflectors, each reflector having an outward-facing surface on which are disposed a plurality of first dipoles arranged in a plurality of first dipole columns, wherein the first dipoles are configured to radiate in a first frequency band, and an inward-facing surface; a first multilayer splitter board having a plurality of first faces, each first face mechanically coupled to the inward-facing surface of one of the plurality of reflectors, wherein the first multilayer splitter board has a plurality of first signal feeds arranged in first signal feed pairs, wherein each first signal feed pair is coupled to a corresponding first splitter output pair disposed on each first face; wherein each splitter output pair is electrically coupled to one of the plurality of first dipole columns disposed on the corresponding reflector; a base plate having a plurality of first ports disposed thereon, and to which each of the plurality of reflectors is mechanically coupled; and a first plurality of RF (Radio Frequency) cables, wherein each of the first plurality of RF cables electrically couples a first port to a corresponding first signal feed.

BRI EF DESCRI PTION OF DRAWINGS

[0005] FIG. 1A illustrates an exemplary small cell antenna having two exemplary multilayer splitter boards according to the disclosure, with one reflector plate removed for the purposes of illustration.

[0006] FIG. IB is a zoomed in view of FIG. 1A.

[0007] FIG. 1C is a top-down view of the exemplary small cell antenna of FIG. 1A, and with all three reflectors present.

[0008] FIG. 2A illustrates an exemplary Mid Band multilayer splitter board according to the disclosure, whereby traces of both layers are visible in the illustration.

[0009] FIG. 2B illustrates a first layer (or first side) of the exemplary multilayer splitter board of FIG. 2A, including its traces.

[0010] FIG. 2C illustrates a second layer (or second side) of the exemplary multilayer splitter board of FIG. 2A, including its traces.

[0011] FIG. 2D illustrates an exemplary ground plane layer disposed between the first and second layers of the first multilayer splitter board.

[0012] FIG. 3A illustrates an exemplary C-Band multilayer splitter board according to the disclosure, whereby traces of both layers are visible in the illustration.

[0013] FIG. 3B illustrates a first layer (or first side) of the exemplary C-Band multilayer splitter board of FIG. 3A, including its traces.

[0014] FIG. 3C illustrates a second layer (or second side) of the C-Band exemplary multilayer splitter board of FIG. 3A, including its traces.

[0015] FIG. 3D illustrates an exemplary ground plane layer disposed between the first and second layers of the second multilayer splitter board. [0016] FIG. 4A illustrates an outward-facing surface of a reflector according to the disclosure.

[0017] FIG. 4B is another view of the outward-facing surface of the exemplary reflector of FIG.

4A, providing additional detail of the Mid Band and C-Band dipoles.

[0018] FIG. 5A illustrates an inward-facing surface of a reflector according to the disclosure, showing an exemplary blind mate clip.

[0019] FIG. 5B is another view of the inward-facing surface of the exemplary reflector of FIG. 5A.

[0020] FIG. 6 illustrates an exemplary RET (Remote Electrical Tilt) mechanism according to the disclosure.

DETAI LED DESCRIPTION OF TH E I NVENTION

[0021] FIG. 1A illustrates an exemplary small cell antenna 100 according to the disclosure.

Antenna 100 is illustrated with two reflector plates 105a and 105b, which are mounted to a base plate 130. A third reflector plate (not shown) has been omitted for the purposes of illustration. It will be understood that addition of the third reflector plate, mounted with reflector plates 105a and 105b, forms a triangular configuration having even angular spacing of 120 degrees.

[0022] Mounted to reflector plates (hereinafter referred to as "reflector") 105a and 105b (as well as the third plate that is not shown) is a first multilayer splitter board 115a and a second multilayer splitter board 115b. In this example, first multilayer splitter board 115a carries RF (Radio Frequency) signals in the Mid Band (MB) frequency range (1695-2690 MHz) and second multilayer splitter board 115b carries RF signals in the C-Band frequency range (3.4-4.2 GHz) to the corresponding radiator feed circuits disposed on reflectors 105a/b/c. Accordingly, first multilayer splitter board 115a may also be referred to as Mid Band multilayer splitter board 115a, and second multilayer splitter board 115b may be referred to as C-Band multilayer splitter board 115b.

[0023] Disposed on the outward-facing surfaces of each reflector 105a/b/c is a plurality of first dipoles 110 that radiate in the Mid band and a plurality of second dipoles (not shown) that radiate in the C-Band.

[0024] Each of the Mid Band 110 and C-Band dipoles radiate two signals, one per orthogonal polarization (e.g., +/- 45 degrees). Accordingly, as used herein, a "signal pair" refers to the two independent signals that are radiated by a single dipole but in orthogonal polarization states. [0025] Disposed on the inward-facing surface of reflector plate 105b is a first RET (remote Electrical Tilt) mechanism 120a, which is mechanically coupled to a first drive shaft 125a. First drive shaft 125a is coupled to three RET struts 127a, each of which engage with a first RET phase shifter assembly (not shown) that is disposed on the outward-facing surface of corresponding reflectors 105a/b/c. First RET phase shifter mechanism 120a is configured to shift the phases of the Mid Band signals provided by first multilayer splitter board 115a to the Mid Band dipoles 110 on reflectors 105a/b/c to provide for beam tilt in the vertical direction. To accommodate the motion of drive shaft 125a, first multilayer splitter board 115a has an aperture (not shown) through which drive shaft 125a translates in the vertical direction.

[0026] Disposed on the inward-facing surface of reflector 105a is a second RET mechanism 120b, which is mechanically coupled to a second drive shaft 125b. Second drive shaft 125b is coupled to three RET struts 127b, each of which engage a second RET phase shifter assembly (not shown) that is disposed on the outward-facing surface of corresponding reflectors 105a/b/c. Second RET phase shifter mechanism 120b is configured to shift the phases of the C- Band signals provided by second multilayer splitter board 115b to the C-Band radiators on reflectors 105a/b/c to provide for beam tilt in the vertical direction. To accommodate the motion of drive shaft 125b, second multilayer splitter board 115b has an aperture (not shown) through which drive shaft 125b translates in the vertical direction.

[0027] Disposed on base plate 130 is a plurality of ports 135. Each port 135 carries an RF signal for a given frequency band (C-Band or Mid Band) for transmission at a given polarization (+/- 45 degrees). In an exemplary embodiment, antenna 100 has eight ports 135, four for C-Band and four for Mid Band, whereby the four Mid Band ports are allocated such that each of two columns of first radiators 110 are provided two Mid Bandsignals, one per +/- 45 degree polarization; and the four C-Band ports are allocated such that each of two columns of second radiators are provided two C-Band signals, one per +/- 45 degree polarization.

[0028] FIG. IB is a closeup of the illustration of FIG. 1A. Illustrated in FIG. IB is RET mechanism 120a and drive shaft 125a, which is coupled to three RET struts 127. First multilayer splitter board 115a has an aperture 117 through which drive shaft 125a may translate in the vertical direction. Also illustrated are Mid Band dipole feed points 140, arranged in clusters of four, two per polarization for its corresponding Mid Band dipole 110.

[0029] FIG. 1C is a top-down (looking down along a vertical axis) view of exemplary small cell antenna 100, with all three reflectors 105a/b/c present. Shown is circular base plate 130 on which are disposed a plurality of ports 135. Also shown is first multilayer splitter board 115a. Each reflector 105a/b/c has two columns of Mid Band dipoles 110. For exemplary small cell antenna 100, each column is fed a single pair of RF signals, one per dipole polarization.

[0030] FIG. 2A illustrates exemplary first multilayer splitter board 115a, which is configured to operate in the Mid Band. First multilayer splitter board 115a has four signal feeds 205, 210, 215, and 220. Signal feeds 205 and 215 may provide distinct RF signals to the +/- 45 degree radiators of one column of Mid Band dipoles 110; and signal feeds 210 and 220 may provide two separate and distinct RF signals to the +/- 45 degree radiators of the other column of Mid Band dipoles 110. Multilayer splitter board 115a may be formed of two PCBs (Printed Circuit Boards) that are sandwiched together with a ground plane layer (not shown) disposed between them. As used herein, the term "PCB structure" may refer to the combination the two PCBs and the ground plane layer disposed therebetween.

[0031] FIG. 2A is illustrated such that the PCB structure of first multilayer splitter board 115a is rendered transparent. Disposed on the first and second side of the PCB structure are pluralities of traces that are coupled through the PCB structure through vias (described below) and apertures/openings in the ground plane layer, which may be optimized for minimal reflected power. The vias are shown as circular features along the traces. Also illustrated is a plurality of splitter outputs 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, and 280.

[0032] In an example arrangement, splitter outputs 225/230 couple distinct RF signals to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a first column of Mid Band dipoles 110 disposed on reflector 105a; splitter outputs 235/240 couple distinct RF signals to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a second column of Mid Band dipoles 110 disposed on reflector 105a. Splitter outputs 245/250 each couple a distinct RF signal to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a first column of Mid Band dipoles 110 disposed on reflector 105b; splitter outputs 255/260 each couple a distinct RF signal to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a second column of Mid Band dipoles 110 disposed on reflector 105b. Splitter outputs 265/270 each couple a distinct RF signal to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a first column of Mid Band dipoles 110 disposed on reflector 105c; splitter outputs 275/280 each couple a distinct RF signal to each of the two radiators (one per polarization) of the Mid Band dipoles 110 of a second column of Mid Band dipoles 110 disposed on reflector 105c. [0033] Signal feed 205 couples to splitter outputs 235, 255, and 275 through a split trace 207; signal feed 210 couples to splitter outputs 225, 245, and 265 through a split trace 212; signal feed 215 couples to splitter outputs 240, 260, and 280 through a split trace 217; and signal feed

220 couples to splitter outputs 230, 250, and 270 through a split trace 222.

[0034] FIG. 2B illustrates a first side of first multilayer splitter board 115a according to the disclosure. Shown are signal feeds 205/210/215/220. Also shown are segments of split traces 207, 212, 217, and 222. Each of split traces 207, 212, 217, and 222 on the first side of Mid Band splitter board 115a has two respective dual-stage transformer segments 207s/207t, 212s/212t, 217s/217t, and 222s/222t, illustrated as wider segments of their respective split traces. Dualstage transformer segments 207s/207t, 212s/212t, 217s/217t, and 222s/222t broaden the bandwidth of the RF signal carried on their respective traces as well as provide for 50 Ohm outputs.

[0035] FIG. 2C illustrates a second side of first multilayer splitter board 115a according to the disclosure. Shown are signal feeds 205, 210, 215, 220, along with complementary segments of split traces 207, 212, 217, and 222, which combine with the segments of the first side illustrated in FIG. 2B.

[0036] FIG. 2D illustrates an exemplary ground plane layer 252, which is disposed between the two PCBs of the PCB structure of first multilayer splitter board 115a. Formed in ground plane layer 252 is a plurality of apertures 257 that are coaxial with the vias (not shown) that electrically couple the segments of split traces 207, 212, 217, 222 that are disposed on first and second side of first splitter board 115a. In an exemplary embodiment, each PCB layer may be 30 mils thick, one of which has ground plane layer 252 disposed on the PCB surface that faces the other PCB. The two PCBs are adhered by a layer of prepreg bonding film that may have a thickness of 4 mils. Ground plane layer 252 may be formed of a 1.4 mil thick sheet of Copper. In the disclosed example, ground plane layer 252 is disposed directly on the first PCB on which the first side traces illustrated in FIG. 2B are disposed. Accordingly, given the 4 mil thickness of the prepreg film disposed between ground plane layer 252 and the second PCB on which the second side traces illustrated in FIG. 2C are disposed, the distance between the second side traces and ground plane layer 252 is 4 mil further that the distance between the first side traces illustrated in FIG. 2B and ground plane layer 252. Accordingly, second side split traces 207, 212, 217, 222 illustrated in FIG. 2C may be wider than first side split traces split traces 207, 212, 217, 222 illustrated in FIG. 2B. Further, each aperture 257 may have a predetermined diameter so that the transition through its corresponding via has a good return loss and minimal reflected power.

[0037] FIG. 3A illustrates exemplary second multilayer splitter board 115b, which is configured to operate in the C-Band. Second multilayer splitter board 115b has four signal feeds 305, 310, 315, and 320. Signal feeds 305 and 315 may provide distinct RF signals to the +/- 45 degree radiators of one column of C-Band dipoles (ref. 405 in FIG.4B); and signal feeds 310 and 320 may provide two separate and distinct RF signals to the +/- 45 degree radiators of the other column of Mid Band dipoles 405. Second multilayer splitter board 115b may have a similar PCB structure to that disclosed above with regard to first multilayer splitter board 115a.

[0038] FIG. 3A is illustrated such that the PCB structure of second multilayer splitter board 115b is rendered transparent. Disposed on the first and second side of the PCB structure are pluralities of traces that are coupled through the PCB structure through vias, and apertures/openings in the ground plane layer which may be optimized for minimal reflected power. The vias are shown as circular features along the traces. Also illustrated is a plurality of splitter outputs 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, and 380.

[0039] Second multilayer splitter board 115b may have three triangular cutouts 390, which provide room within antenna 100 for routing RF cables (not shown) from the four ports 135 carrying Mid Band RF signals to the signal input feeds of first multilayer splitter board 115a.

[0040] Signal feed 305 couples to splitter outputs 330, 350, and 370 through split trace 307; signal feed 310 couples to splitter outputs 340, 360, and 380 through split trace 312; signal feed 315 couples to splitter outputs 325, 345, and 365 through split trace 317; and signal 320 couples to splitter outputs 335, 355, and 375 through split trace 322.

[0041] FIG. 3B illustrates a first side of second multilayer splitter board 115b according to the disclosure. Shown are signal feeds 305/310/315/320. Also shown are segments of split traces 307, 312, 317, and 322. Each of split traces 307, 312, 317, and 322 on first side of second splitter board 115b has respective dual-stage transformer segments 307s/307t, 312s/312t, 317s/317t, and 322/s322t, illustrated as wider segments of their respective split traces. Dual-stage ransformer segments 307s/307t, 312s/312t, 317s/317t, and 322s/322t broaden the bandwidth of the RF signal carried on their respective traces as well as provide for 50 Ohm output.

[0042] FIG. 3C illustrates a second side of second multilayer splitter board 115b according to the disclosure. Shown are signal feeds 305/310/315/320, along with complementary segments of split traces 307, 312, 317, and 322, which combine with the segments of the first side illustrated in FIG. 3B.

[0043] FIG. 3D illustrates an exemplary ground plane layer 352, which is disposed between the two PCBs of the PCB structure of first multilayer splitter board 115b. Formed in ground plane layer 352 is a plurality of apertures 357 that are coaxial with the vias (not shown) that electrically couple the segments of split traces 307, 312, 317, 322 that are disposed on first and second side of second splitter board 115b. In an exemplary embodiment, each PCB layer may be 30 mils thick, one of which has ground plane layer 352 disposed on the PCB surface that faces the other PCB. The two PCBs are adhered by a layer of prepreg bonding film that may have a thickness of 4 mils. Ground plane layer 352 may be formed of a 1.4 mil thick sheet of Copper. In the disclosed example, ground plane layer 352 is disposed directly on the first PCB on which the first side traces illustrated in FIG. 3B are disposed. Accordingly, given the 4 mil thickness of the prepreg film disposed between ground plane layer 352 and the second PCB on which the second side traces illustrated in FIG. 3C are disposed, the distance between the second side traces and ground plane layer 352 is 4 mil further that the distance between the first side traces illustrated in FIG. 3B and ground plane layer 252. Accordingly, second side split traces 307, 312, 317, 322 illustrated in FIG. 3C may be wider than first side split traces split traces 307, 312, 317, 322 illustrated in FIG. 3B. Further, each aperture 357 may have a predetermined diameter so that the transition through its corresponding via has a good return loss and minimal reflected power.

[0044] FIG. 4A illustrates an outward-facing surface of a reflector 105c according to the disclosure. Reflector 105c may have a blind mate coupler (not shown) that enables reflector 105c to be mounted to antenna 100 once reflectors 105a and 105b have been installed. Shown in FIG. 4A are simplified illustrations of Mid Band dipoles 110 that are disposed on respective Mid Band feed boards 407; and simplified illustrations of C-Band dipoles 405 disposed on C- Band feed boards 415. Protruding through C-Band splitter board 415 is C-Band feed tab 410, which may be one of split traces 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, or 380. Feed tab 410 has three conductive contacts: a signal feed contact 412 (center trace), which couples one of the split traces (325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, or 380) to splitter board trace 413; and two ground contacts 411, which electrically couple to ground plane layer 352 and the splitter board ground plane (not shown). The spacing between feed contact 412 and ground contacts 411 may be selected so that they are far enough apart for ease of manufacture but narrow enough to take up a small area. Signal feed contact 412 may be coupled to a corresponding split trace, and ground contacts 411 may be coupled to ground plane layer 352, using solder connections, or by a PCB-to-PCB connector.

[0045] Also shown is an aperture 420 formed in reflector 105, which allows access to vertical launch clips 425 that are mechanically coupled to two adjacent signal feeds 305/310 or 315/320. The presence of aperture 420 enables easy access to the solder joints at which RF cables (not shown) are coupled to vertical launch clips 425. One set of solder joints may couple an RF center pin to the top copper feed board interface, and another set of solder joints may couple the RF cable outer jacket to the vertical launch clip interface. Aperture 420 is optional: although it provides access to solder joints, it may take up space on reflector 105c.

[0046] FIG. 4B is another view of an outward-facing surface of reflector 105c, including a more detailed view of the conductor patterns on Mid Band dipoles 110 and C-Band dipoles 405. As illustrated, Mid Band dipoles 110 and C-Band dipoles may be folded dipole configurations. A more detailed description of exemplary folded dipoles may be found in co-owned International Patent Application W02023/224966, FOLDED MID BAND DIPOLE WITH IMPROVED LOW BAND TRANSPARENCY; and US Patent 11,581,660, HIGH PERFORMANCE FOLDED DIPOLE FOR MULTIBAND ANTENNAS, both of which are incorporated by reference as if fully disclosed herein. Although FIG. 4B is of reflector 105c, it will be understood that the arrangement of Mid Band dipoles 110 and C-Band dipoles 405 may be identical to those on reflectors 105a/b.

[0047] FIG. 5A illustrates an inward-facing surface of a reflector 105c according to the disclosure. Shown are first multilayer splitter board 115a affixed to reflector 105c by a blind mate coupler 505. Blind mate coupler 505 may be formed of plastic and may be pre-loaded or snapped into place on the inward-facing surface of reflector 105c. Although not shown in FIG. 5A, reflector 105c has a second blind mate coupler 505 that is affixed to inward-facing surface of reflector 105c on the opposite side of aperture 420.

[0048] Blind mate coupler 505 has a tab 510 that structurally fixes first multilayer splitter board 115a to reflector 105c; and two blind mate guides 515 disposed on opposite sides of tab 510. Blind mate guides 515 may have a semi-cylindrical shape that has upper and lower arms (only the upper arms are illustrated in FIG. 5A) that guide first multilayer splitter board 115a into place so that it can be held rigid by tab 510. The placement of the tabs 510 in relation to the blind mate guides 515 can vary. Multiple other geometries could also be used to achieve the same blind mate effect. For example, blind mate coupler 505 may have more tabs 510 at different spacing on either side of the blind mate guides 515. [0049] Also shown in FIG. 5A are two vertical launch clips 425 at which RF cables (not shown) may be affixed to provide RF signals from corresponding ports 135 to signal feeds 205/210 or 215/220. A more detailed description of vertical launch clips 425 may be found in co-owned International Patent Application W02022/246192, LOW-COST MINIATURIZED VERTICAL COAXIAL CABLE TO PCB TRANSITION FOR USE IN ULTRA-DENSE BASE STATION ANTENNAS, which is incorporated by reference is if fully disclosed herein.

[0050] Although FIG. 5A is described in the context of mounting first multilayer splitter board 115a to reflector 105c, it will be understood that reflector 105c may have two additional blind mate couplers 505 affixed to reflector 105c for mounting second multilayer splitter board 115b.

[0051] FIG. 5B is another view of the inward-facing surface of exemplary reflector 105c. As illustrated, first multilayer splitter board 115a is affixed to reflector 105c, held rigid by tabs 510 of blind mate couplers 505.

[0052] First (Mid Band) multilayer splitter board 115a may preferably be disposed above second (C-Band) multilayer feedboard 115b along the vertical axis. This is because signal loss may be more prevalent in the C-Band than in the Mid Band so it would be advantageous for the C-Band cabling (not shown) from the ports 135 to C-Band multilayer splitter board 115b.

[0053] Although the above discussion describes the multilayer splitter boards 115a/b as having signal feeds and splitter outputs, it will be understood that signals pass bidirectionally and that the multilayer splitter boards 115a/b combine receive signals as well as split transmit signals.

[0054] An advantage of the disclosed antenna 100 is that far fewer RF cables are required. For example, as mentioned above, antenna 100 has eight ports 135. Coupled to each port 135 is an RF cable (not shown). Four of these RF cables are each coupled to one of the signal feeds 305, 310, 315, 320 on second multilayer splitter board 110b. This may be done by soldering each RF cable to a corresponding signal feed at its vertical launch clip 425. Alternatively, cables may be coupled electrically and mechanically by means other than soldering, for example using snap in connector. It will be understood that such variations are possible and within the scope of the disclosure.

[0055] Each of the other four RF cables may be routed past second multilayer splitter board

115b via a closest triangular cutout 390 on second multilayer splitter board 115b to be soldered to its vertical launch clip on one of signal feeds 205, 210, 215, or 220 on first multilayer splitter board 115a. [0056] FIG. 6 illustrates an exemplary first RET (remote Electrical Tilt) mechanism 120a, which is mechanically coupled to a first drive shaft 125a. Given that the first RET mechanism 120a and second RET mechanism 120b has the same components, the description below applies to both devices. First drive shaft 125a is coupled to three RET struts 127, each of which engage with a RET phase shifter assembly (not shown) that is disposed on the outward-facing surface of corresponding reflector plates 105a/b/c. RET mechanism 120 has a motor 605, which may be transverse mounted, and may be coupled to an axle 615, which is mechanically coupled to a rack and pinion mechanism 610. Rack and pinion mechanism 610 may be mechanically coupled to a carriage 620, which is mechanically coupled to drive shaft 125. Motor 605 and rack and pinion mechanism 610 may be mechanically coupled to a gear box 625, which serves as a platform and housing for the components.

[0057] The disclosed RET mechanism 120 offers certain advantages. First, it is more compact than conventional RET mechanisms, which may be important in a small cell antenna. Second, rack and pinion mechanism 610 enables faster motion that conventional lead screw designs, which may allow for more immediate feedback to network engineers adjusting RET mechanism 120 to a desired tilt angle. Third, it may require less torque than a conventional lead screw design, which may make exemplary RET mechanism 120 more reliable.

[0058] Although the example antenna 100 disclosed above supports two frequency bands and has two multilayer splitter boards (one multilayer splitter board per frequency band), it will be understood that antenna 100 may have only one multilayer splitter board that supports one or multiple frequency band. In another variation, antenna 100 may support three or more frequency bands, in which case it could have additional multilayer splitter boards, one per supported frequency band, or alternatively, all splitters could be present within a single multilayer board. Although the example antenna 100 disclosed has each input signal split 3-ways to three output signals, each of which couple to a first column of MB radiators or second column of C-Band radiators, it will be understood that antenna 100 may split each input signal M ways to connect to N reflectors to feed P columns. It will be understood that such variations are possible and within the scope of the disclosure.

[0059] Although exemplary antenna 100 is disclosed as having three reflectors 105 arranged in a triangular configuration, it will be understood that it may have more or fewer reflectors 105. Such arrangements may include pentagonal or hexagonal configurations. It will be understood that such variations are possible and within the scope of the disclosure. [0060] First and second frequency bands may be other frequency bands (than Mid Band and C- Band, respectively) that used in radio communication. It will be understood that such variations are possible and within the scope of the disclosure.

Claims

1. An antenna, comprising: a plurality of reflectors, each reflector having an outward-facing surface on which are disposed a plurality of first dipoles arranged in a plurality of first dipole columns, wherein the first dipoles are configured to radiate in a first frequency band, and an inward-facing surface; a first multilayer splitter board having a plurality of first faces, each first face mechanically coupled to the inward-facing surface of one of the plurality of reflectors, wherein the first multilayer splitter board has a plurality of first signal feeds arranged in first signal feed pairs, wherein each first signal feed pair is coupled to a corresponding first splitter output pair disposed on each of the plurality of first faces; and wherein each splitter output pair is electrically coupled to one of the plurality of first dipole columns disposed on the corresponding reflector; a base plate having a plurality of first ports disposed thereon, and to which each of the plurality of reflectors is mechanically coupled; and a first plurality of RF (Radio Frequency) cables, wherein each of the first plurality of RF cables electrically couples a corresponding one of the first plurality of ports to a corresponding first signal feed.

2. The antenna of claim 1, wherein the first multilayer splitter board comprises: a first PCB (Printed Circuit Board) having a first plurality of first signal traces disposed thereon; a second PCB having a second plurality of first signal traces disposed thereon; a plurality of vias formed in the first PCB and the second PCB, wherein each of the vias electrically couple one of the first plurality of first signal traces to one of the first plurality of second signal traces; and a ground plane layer disposed between the first PCB and the second PCB, the ground plane layer having a plurality of apertures that are disposed such that each surrounds a corresponding via.

3. The antenna of claim 1, wherein each reflector comprises a plurality of second dipoles disposed thereon in a plurality of second dipole columns, wherein the second dipoles are configured to radiate in a second frequency band.

4. The antenna of claim 3, further comprising; a second multilayer splitter board having a plurality of second faces, each second face mechanically coupled to the inward-facing surface of one of the plurality of reflectors, wherein the second multilayer splitter board has a plurality of second signal feeds arranged in second signal feed pairs, wherein each second signal feed pair is coupled to a corresponding second splitter output pair disposed on each of the plurality of second faces; and wherein each splitter output pair is electrically coupled to one of the plurality of second dipole columns disposed on the corresponding reflector; and a second plurality of RF (Radio Frequency) cables, wherein the base plate has a plurality of second ports disposed thereon, and wherein each of the second plurality of RF cables electrically couples a corresponding one of the plurality of second ports to a corresponding second signal feed.

5. The antenna of claim 4, wherein the second multilayer splitter board comprises: a first PCB having a first plurality of second signal traces disposed thereon; a second PCB having a second plurality of second signal traces disposed thereon; a plurality of vias, wherein each of the vias electrically couple one of the first plurality of second signal traces to one of the second plurality of second signal traces; and a ground plane layer disposed between the first PCB and the second PCB, the ground plane layer having a plurality of apertures that are disposed such that each surrounds a corresponding via.

6. The antenna of claim 4, wherein each of the plurality of first signal feeds and second signal feeds comprises a vertical launch clip.

7. The antenna of claim 4 further comprising: a first blind mate coupler that mechanically couples one of the plurality of reflectors to the first multilayer splitter board; and a second blind mate coupler that mechanically couples one of the plurality of reflectors to the second multilayer splitter board.

8. The antenna of claim 7, wherein each blind mate coupler comprises: a tab; and a blind mate guide.

9. The antenna of claim 1, wherein the plurality of reflectors comprises three reflectors that are triangularly arranged.

10. The antenna of claim 1, wherein the first frequency band comprises a Mid Band, and wherein the second frequency band comprises a C-Band.

11. The antenna of claim 1, further comprising a RET (Remote Electrical Tilt) mechanism, wherein the RET mechanism comprises: a gearbox; a motor that is mechanically coupled to the gearbox, the motor having an axle; a rack and pinion mechanism mechanically coupled to the axle; a carriage translatably mechanically coupled to the rack and pinion mechanism; a drive shaft mechanically coupled to the carriage; and a plurality of struts mechanically coupled to the drive shaft.

12. An antenna comprising: a plurality of reflectors, each reflector having an outward-facing surface on which are disposed a plurality of first dipoles arranged in a plurality of first dipole columns, wherein the first dipoles are configured to radiate in a first frequency band, and an inward-facing surface; a first multilayer splitter board mechanically coupled to the inward-facing surface of each of the plurality of reflectors, wherein the first multilayer splitter board has a plurality of first signal feeds arranged in first signal feed pairs, wherein each of the first signal feed pairs is coupled to a corresponding first one of the plurality of first dipole columns on each of the plurality of reflectors; a first plurality of RF (Radio Frequency) cables, wherein each of the first plurality of RF cables electrically couples to a corresponding first signal feed; a second multilayer splitter board mechanically coupled to the inward-facing surface of each of the plurality of reflectors, wherein the second multilayer splitter board has a plurality of second signal feeds arranged in second signal feed pairs, wherein each of the second signal feed pairs is coupled to a corresponding second one of the plurality of first dipole columns on each of the plurality of reflectors; and a second plurality of RF cables, wherein each of the second plurality of RF cables electrically couples to a corresponding second signal feed.

13. The antenna of claim 12, wherein each first signal feed pair is coupled to a plurality of first splitter output pairs, and wherein each of the plurality of first splitter output pairs is electrically coupled to a corresponding first one of the plurality of first dipole columns on each of the plurality of reflectors, and wherein each second signal feed pair is coupled to a plurality of second splitter output pairs, and wherein each of the plurality of second splitter output pairs is electrically coupled to a corresponding second one of the plurality of first dipole columns on each of the plurality of reflectors.

14. The antenna of claim 12 further comprising: a base plate having a plurality of first ports and second ports disposed thereon, and to which each of the plurality of reflectors is mechanically coupled, wherein each of the first plurality of RF cables electrically couples a corresponding one of the plurality of first ports to the corresponding first signal feed, and wherein each of the second plurality of RF cables electrically couples a corresponding one of the plurality of second ports to the corresponding second signal feed.