Directive antenna with loaded flat dielectric layers

Abstract

An antenna has a column of dipoles on which is disposed a stack of dielectric panels that collectively form a dielectric lens stack. The dielectric lens stacks disposed the dipole column provides for beam shaping that offers an effective substitute for array factor. In other words, the use of a dielectric lens stack provides beam shaping that would otherwise require two or more columns of dipoles disposed adjacent along the azimuth. This not only increases the complexity of the antenna's circuity, and worsens the effect of interband interference with dipoles in other frequency bands, but it also increases the width of the reflector in the x-direction, worsening the wind loading of the antenna. The use of a dielectric lens stack mitigates these issues.

Description

[0001] Directive Antenna with Loaded Flat Dielectric Layers

[0002] BACKGROU ND OF THE INVENTION

[0003] [1] Cellular antenna designers are under increasing demand to improve the beam quality - particularly in the azimuth plane - while not increasing the width of the antenna, which may incur increased wind loading. Conventional solutions to improving beam quality and controlling beam width involve adding columns of dipoles to take advantage of array factor. However, this may increase the complexity of the antenna as well as increase its width.

[0004] Further to the conventional solution, for multiband antennas, operating in frequencies such as low band (LB)(617-894 MHz), mid band (MB)(1695-2690 MHz), C-Band and CBRS (Citizens Broadband Radio Service)(3.4-4.2 GHz), adding columns of dipoles may result in increase interband interference due to arrays of dipoles of different frequency bands being interleaved or otherwise in close proximity to each other.

[0005] [2] Accordingly, what is needed is a way to improve beam quality and control beam width for a single column of dipoles.

[0006] SUMMARY OF THE INVENTION

[0007] [3] An aspect of the disclosure involves an antenna. The antenna comprises a reflector; a column of dipoles disposed on the reflector; and a dielectric lens stack disposed above the column of dipoles along the z-axis.

[0008] BRIEF DESCRIPTION OF DRAWINGS

[0009] [4] FIG. 1A illustrates an exemplary C-Band dipole column assembly having a dielectric lens stack according to the disclosure, viewed along the x-axis (or azimuth axis).

[0010] [5] FIG. IB illustrates the C-Band dipole assembly of FIG. 1 from along the y-axis (or elevation axis)

[0011] [6] FIG. 1C is a tilted view of the exemplary C-Band dipole assembly of FIG. 1.

[0012] [7] FIG. 2 illustrates an exemplary C-Band dipole.

[0013] [8] FIG. 3A illustrates an exemplary Low Band dipole assembly having a dielectric lens stack according to the disclosure, viewed along the y-axis.

[0014] [9] FIG. 3B is a tilted view of the exemplary Low Band dipole assembly of FIG. 5A.

[0010] FIG. 4 provides two views a pair of Low Band dipoles as may be used in two Low Band dipole assemblies according to the disclosure.

[0015]

[0011] FIG. 5A Illustrates a column of Low Band dipole assemblies, viewed along the x-axis.

[0016]

[0012] FIG. 5B is a tilted view of the column of Low Band dipole assemblies of FIG. 7A.

[0017]

[0013] FIG. 6 illustrates an exemplary dielectric lens stack as may be used with a Low Band dipole.

[0018]

[0014] FIG. 7 illustrates an exemplary antenna having a single exemplary single C-Band dipole column, as viewed along the y-axis.

[0019]

[0015] FIG. 8A illustrates an exemplary antenna having a single column of C-Band dipoles with two C- Band dielectric stack assemblies, along with two Low Band dipoles, As viewed along the x-axis.

[0020]

[0016] FIG. 8B is a view of the exemplary antenna of FIG. 8A, but along the z-axis, showing an exemplary mounting bracket for the C-Band dielectric stack assembly.

[0021]

[0017] FIG. 9 illustrates an exemplary dielectric stack lens as may be used with a C-Band dipole.

[0022]

[0018] FIG. IDA illustrates an exemplary antenna having C-Band dipole and stack assemblies according to a second embodiment.

[0023]

[0019] FIG. 10B shows the antenna of FIG. IDA from along the z-axis.

[0024]

[0020] FIG. 10C illustrates an exemplary C-Band dipole and stack assembly as used in the antenna of FIG. 10A.

[0025]

[0021] FIG. 10D shows the C-Band dipole and stack assembly of FIG. 10B from along the y-axis.

[0026]

[0022] FIG. 10E is tilted view of the C-Band dipole and stack assembly of FIG. 10B.

[0027]

[0023] FIG. 11 is a plot showing azimuth beamwidth achieved by C-Band dipole and stack assembly as a function of the number of dielectric plates used.

[0028] DETAI LED DESCRIPTION OF TH E I NVENTION

[0029]

[0024] FIG. 1A illustrates an exemplary C-Band dipole column assembly 100 having a dielectric lens stack 115 according to the disclosure, viewed along the x-axis (i.e., azimuth axis), which is perpendicular to the y-axis and z-axis illustrated in FIG. 1A. C-Band dipole column assembly 100 may be disposed on a reflector 105. C-Band dipole column assembly 100 has a plurality of C-Band dipoles 110 that may be arranged in a column along the y-axis (i.e., elevation axis) as shown in FIG. 1A. Alternatively, the plurality of C-Band dipoles assembly may be arranged as a in a row along the x-axis of an antenna. Dielectric lens stack 115 has a plurality of dielectric panels 120. The dielectric panels 120 may have a rectangular shape. The rectangular shape may have rounded corners or may have right angle corners. However, other shapes are considered to be within the inventive concept of this disclosure.

[0030]

[0025] FIG. IB illustrates the C-Band dipole assembly of FIG. 1 from along the y-axis. Exemplary dielectric lens stack 115 may have seven dielectric panels 120, each of which has a thickness Tiayer, and each of which may be mounted with a spacing Siayer between adjacent dielectric panels 120 along the z-axis. The dielectric lens stack 115 may be spaced from C-Band dipole 110 by a distance 117, and may have a width 119. The construction of the dielectric lens stack 115 may employ the principle of the effective medium. It's function is akin to a thick dielectric lens, achieved through the use of multiple sandwich structures composed of dielectric panels 120 and air layers. A variety of dielectric materials, including but not limited to FR4, plastic, Teflon, polyethylene, and glass, can be utilized for these thin dielectric layers. The requirement for the air layer varies, with a thinner layer (lower Siayer value) needed for a low dielectric layer and a thicker one (high Siayer value) for a high dielectric layer. The thickness and spacing of the dielectric panels 120 are determined based on the dielectric constant of the dielectric layer. While a wider dielectric layer (e.g., along the x-axis) results in a clearer beam, an example width may be 0.5X, wherein lambda is the wavelength at the lowest transmitted frequency. In an example embodiment, Tiayer may be 60mil and Siayer may be 5.97mm.

[0031]

[0026] Although seven dielectric panels 120 are shown in dielectric lens stack 115, it will be understood that more or fewer panels 120 may be used. Generally, the greater the number of dielectric panels 120, the greater the lensing effect, and the narrower the beamwidth in the azimuth plane (defined by the x-axis and z-axis). A narrower beam may be achieved by leveraging multiple reflections within an effective medium. Specifically, the constructive and destructive interference resulting from multiple reflections off dielectric panels 120 enables improved beam focusing in the boresight direction (along the z-axis). For example, a dielectric lens stack 115 having eight dielectric panels 120 may impart an azimuth beamwidth of 45 degrees.

[0032]

[0027] FIG. 1C is a tilted view of the exemplary C-Band dipole column assembly 100 disposed on reflector 105.

[0033]

[0028] FIG. 2 illustrates an exemplary C-Band dipole 110 as may be used in C-Band dipole column assembly 100 according to the disclosure. C-Band dipole 110 may have a set of dipole arms 205, which are electrically coupled to balun circuitry (not shown) disposed on balun stem 210, which also provides mechanical support for dipole arms 205. Balun stem 210 may be electrically coupled to feed circuitry (partially shown) on a feed board 215, which may be mechanically coupled to reflector 105.

[0034]

[0029] C-Band dipole 110 may be a folded dipole configuration. A more detailed description of exemplary folded dipole configurations may be found in co-owned International Patent Application WO2023 / 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. It should be noted, the present disclosure is not limited to the specific configuration for C-Band dipole 110.

[0035]

[0030] FIG. 3A illustrates an exemplary Low Band dipole assembly 300 having a dielectric lens stack 315 according to the disclosure, as viewed along the y-axis. Low Band dipole assembly 300 has a Low Band dipole 310, which is disposed on a reflector 305. Mounted above (i.e., along the z- axis) Low Band dipole 310 is dielectric lens stack 315, which in this example has 25 dielectric panels 320. Each dielectric panel 320 may have the same thickness Tiaras the dielectric panels 120 described above, and may be spaced apart in the z-axis direction Siayer along the z- axis as dielectric lens stack 115 above. In an example embodiment, the values for Tiayer and Siayer may both be 6mm. In an example embodiment, each dielectric panel 320 in dielectric lens stack 315 may have a circular shape. As stated above, the dielectric panels may be rectangular; however, in this illustration, they are circular in shape. In an exemplary embodiment, each dielectric panel 320 may have a diameter of 276mm and a thicknkess Tiayer of 6mm. And each adjacent dielectric panel 320 may be spaced apart (Siayer) by 6mm. Each Further, disposed between Low Band dipole 310 and dielectric lens stack 315 is a director, or passive radiator 325, which may provide for additional tuning of the shape of the beam emitted by Low Band dipole 310 as well as increase bandwidth.

[0036]

[0031] FIG. 3B is a tilted view of exemplary Low Band dipole assembly 300, providing another perspective.

[0037]

[0032] FIG. 4 provides two views of a pair of Low Band dipoles 310 as may be used in a two-Low Band dipole assembly 400 according to the disclosure, along with respective directors 325. It will be understood that the Low Band dipoles 310 in FIG. 4 would be part of a Low Band dipole assembly 300, as shown in FIG. 3B, with a corresponding dielectric lens stack 315.

[0038]

[0033] FIG. 5A illustrates an antenna assembly 500 comprising a column of Low Band dipole assemblies 300. The dielectric lens stacks 315 disposed above each (i.e., along the z-axis) Low Band dipole 310 provides for beam shaping that offers an effective substitute for array factor. In other words, the use of dielectric lens stacks 315 provides beam shaping that would otherwise require two or more columns of Low Band dipoles 310 disposed adjacent along the x-axis. This not only increases the complexity of the antenna's circuity, and worsens the effect of interband interference with dipoles in other frequency bands, but it also increases the width of the reflector in the x-direction, worsening the wind loading of the antenna.

[0039]

[0034] FIG. 5B is a tilted view of the column of Low Band dipole assemblies 300 illustrated in FIG. 5A.

[0040]

[0035] The 0.5A width relationship may apply both to the Low Band as well as C-Band. Generally, the wider the dielectric layer, the narrower the beam. However, space constraints within the antenna radome may place a practical limit on the width.

[0041]

[0036] FIG. 6 illustrates an exemplary dielectric lens stack 600 as may be used with Low Band dipole 310. Dielectric lens stack 600 has a plurality (in this example, five) of dielectric panels 620, which may be formed of Plexiglass having a dielectric constant of 3.4 and a thickness of 6mm. Adjacent dielectric panels 620 may be spaced apart by 6mm.

[0042]

[0037] FIG. 7 illustrates an exemplary antenna 700 having a single exemplary single C-Band dipole column, as viewed along the y-axis. Given that the view is along the y-axis, the column appears as a single C-Band dipole 110 disposed on reflector 705. Disposed above the C-Band dipole column is a dielectric lens stack 715 having a plurality of dielectric panels 620 within radome 710. One skilled in the art will appreciate that the C-Band dipole column comprises a plurality of C-Band dipoles 110 positioned along the y-axis.

[0043]

[0038] FIG. 8A illustrates an exemplary antenna 800 having a single column of C-Band dipoles 110 with two C-Band dielectric stack assemblies 815, along with a plurality of Low Band and Mid Band dipole assemblies 850, As viewed along the x-axis. The Low Band and Mid Band dipole assemblies 850 are disposed on reflector 805, and the C-Band dipoles 110 are disposed on an elevated reflector 825 that is disposed above reflector 805.

[0044]

[0039] FIG. 8B shows exemplary antenna 800 from along the y-axis. Shown are Low Band and Mid Band dipole assemblies 850, each having one Low Band dipole 851 and four Mid Band dipoles 852; elevated reflector 825, on which is disposed a column of C-Band dipoles 110 as well as the dielectric stack assemblies 815 (only one visible given the perspective along the y-axis). Here, dielectric stack assembly 815 has a mounting rack 820, which holds the plurality of dielectric panels 620. In this example embodiment, dielectric stack assembly 815 has seven dielectric panels 620.

[0040] Elevated reflector 825 provides phase matching from radome 810, thereby reducing phase cancellation of the RF (Radio Frequency) signal emitted by C-Band dipoles 110 and reflected off the interior surface of radome 810. The use of elevated reflector 825 is optional, whereby one may forego the reduction of phase cancellation in exchange for a simplified antenna structure.

[0045]

[0041] FIG. 9 illustrates a variation of exemplary dielectric stack lens 815 having eight dielectric panels 920, for use with C-Band dipole 110. Mounting rack 820 has been omitted for the purposes of illustration. Each dielectric panel 920 may be formed of a PCB (Printed Circuit Board) material having a dielectric constant of 3.48, such as Rogers RO4350, having a thickness of 60 mil. Adjacent dielectric panels 920 may be spaced at 5.97mm, as illustrated.

[0046]

[0042] FIG. 10A illustrates an exemplary antenna 1000 having two C-Band dipole and stack assemblies 1010 according to an embodiment. The two C-Band dipole and stack assemblies 1010 may be arranged in a single column along the y-axis. Each C-Band dipole and stack assembly 1010 has a plurality of C-Band dipoles 110 (in this example, five), over which is disposed a dielectric stack assembly 1015 whereby the dielectric plates are held in place by a set of mounting racks 1020 that are mechanically coupled to elevated reflector 1025.

[0047]

[0043] FIG. 10B is a view of antenna 1000 from along the z-axis, and with the addition of four Low Band and Mid Band dipole assemblies 1050. Given that C-Band dipole and stack assemblies 1010 are integrated with a dielectric stack assembly 1015, the lensing affect of the dielectric stack assembly 1015 provides for azimuth beam control that would otherwise require additional columns of C-Band dipoles 110. Reducing the C-Band dipoles 110 to a single column frees up space on reflector 1005 for placement of additional Low Band and Mid Band dipole assemblies 1050.

[0048]

[0044] FIG. 10C illustrates a single C-Band dipole and stack assembly 1010, viewed from along the x- axis. Exemplary C-Band dipole and stack assembly 1010 has five C-Band dipoles 110 disposed on an elevated reflector 1025, and a dielectric stack assembly 1015 that has seven dielectric plates 905 that are held in place by four mounting racks 1020. Each mounting rack 1020 has a plurality of slots 1022 that hold dielectric plates 905 in place. In this example, mounting rack 1020 has eight slots 1022, only seven of which are supporting a dielectric plate 905. Accordingly, more or fewer dielectric plates 905 may be installed to more finely tune the azimuth beamwidth of the column of C-Band dipoles 110.

[0049]

[0045] FIG. 10D illustrates the C-Band dipole and stack assembly 1010 from along the y-axis.

[0046] FIG. IDE is a tilted view of exemplary C-Band dipole and stack assembly 1010.

[0050]

[0047] FIG. 11 is a plot showing azimuth beamwidth achieved by exemplary C-Band dipole and stack assembly 1010 as a function of the number of dielectric plates 905 used.

Claims

Claims1. An antenna, comprising: a reflector; a column of dipoles disposed on the reflector; and a dielectric lens stack disposed above the column of dipoles along a z-axis direction of the antenna, wherein the dielectric lens stack has a plurality of dielectric plates that are spaced apart along the z-axis direction.

2. The antenna of claim 1, wherein each of the plurality of dielectric plates comprises one of FR4, plastic, Teflon, polyethylene, and glass.

3. The antenna of claim 1, wherein the column of dipoles comprises a plurality of Low Band dipoles.

4. The antenna of claim 3, wherein each of the plurality of dielectric plates comprises a plurality of circular dielectric plates.

5. The antenna of claim 4, wherein each of the plurality of dielectric plates comprises a dielectric constant of 3.4.

6. The antenna of claim 5, wherein each of the plurality of dielectric plates comprises a thickness of 6mm.

7. The antenna of claim 6, wherein the plurality of dielectric plates are spaced apart along the z- axis directoin of the antenna by a distance of 6mm.

8. The antenna of claim 1, wherein the column of dipoles comprises a plurality of C-Band dipoles.

9. The antenna of claim 8, wherein each of the plurality of dielectric plates comprises a rectangular shape.

10. The antenna of claim 9, wherein each of the plurality of dielectric plates comprises a width of one half the lowest frequency transmitted by each of the plurality of C-Band dipoles.

11. The antenna of claim 10, wherein each of the plurality of dielectric plates comprises a thickness of 60mil.

12. The antenna of claim 11, wherein the dielectric plates are spaced apart along the z-axis direction of the antenna by a distance of 5.97mm.

13. The antenna of claim 9, wherein the plurality of C-Band dipoles are disposed on an elevated reflector, wherein the elevated reflector is mechanically coupled to the reflector and above the reflector along the z-axis direction of the antenna.

14. The antenna of claim 9, wherein the dielectric lens stack comprises a mounting rack, wherein the mounting rack comprises a plurality of slots, each configured to receive one of the plurality of dielectric plates15. An antenna comprising a first C-Band dipole stack assembly comprising a plurality of C-Band dipoles mounted on a first reflector and a C-Band dielectric lens stack assembly over the plurality of C-Band dipoles in a z- axis direction of the antenna; a first and a second column of Low Band and Mid Band dipole assemblies parallel to and on opposite sides of the first C-Band dipole stack assembly, wherein the first and second column of Low Band and Mid Band dipole assemblies are mouned to a second reflector, wherein the first reflector is offset in a z-axis direction of the antenna relative to the second reflector, and wherein the C-Band dielectric lens stack assembly comprises a plurality of dielectric plates spaced apart from each other along the z-axis direction of the antenna.

16. The antenna of claim 15 further comprising a mounting rack, the mounting rack comprising a plurality of slots, each configured to receive a corresponding one of the plurality of dielectric plates.

17. The antenna of claim 15 further comprising: a second C-Band dipole stack assembly comprising a second plurality of C-Band dipoles mounted on a second first reflector and a second C-Band dielectric lens stack assembly over the second plurality of C-Band dipoles in a z-axis direction of the antenna, wherein the second C-Band dipole stack assembly is aligned with the first C-Band dipole stack assembly along a y-direction of the antenna18. An antenna, comprising: a reflector; a dipole disposed on the reflector; and a dielectric lens stack disposed above the dipole, wherein the dielectric lens stack has a plurality of dielectric plates that are spaced apart along a z-axis direction of the antenna.

19. The antenna of claim 18 further comprising: a plurality of dipoles arranged in a column along a y-axis direction of the antenna, wherein each of the plurality of dipoles has disposed there-over a dielectric lens stack comprising a plurality of dielectric plates spaced apart along the z-axis direction of the antenna.

20. The antenna of claim 18 further comprising: a plurality of dipoles arranged in a row along an x-axis direction of the antenna, wherein each of the plurality of dipoles has disposed there-over a dielectric lens stack comprising a plurality of dielectric plates spaced apart along the z-axis direction of the antenna.

Images