EP2891211B1

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Publication number: EP2891211B1
Application number: EP13833558.3A
Authority: EP
Inventors: Chris Hills; Alastair Wright; Ian Renilson
Original assignee: Commscope Technologies LLC
Current assignee: Commscope Technologies LLC
Priority date: 2012-08-31
Filing date: 2013-05-08
Publication date: 2022-02-16
Anticipated expiration: 2033-05-08
Also published as: WO2014035493A1; BR112015003156A2; EP2891211A4; BR112015003156B1; EP2891211A1; CN104685711A; BR112015003156A8; CN104685711B

Description

BACKGROUND

Field of the Invention

This invention relates to microwave reflector antennas. More particularly, the invention relates to a reflector antenna with a radome and reflector dish interconnection band clamp which enhances signal pattern and mechanical interconnection characteristics.

Description of Related Art

The open end of a reflector antenna is typically enclosed by a radome coupled to the distal end of the reflector dish. The radome provides environmental protection and improves wind load characteristics of the antenna.
Edges and/or channel paths of the reflector dish, radome and/or interconnection hardware may diffract or enable spill-over of signal energy present in these areas, introducing undesirable backlobes into the reflector antenna signal pattern quantified as the front to back ratio (F/B) of the antenna. The F/B is regulated by international standards, and is specified by for example, the FCC in 47 CFR Ch.1 Part 101.115 in the United States, by ETSI in EN302217-4-1 and EN302217-4-12 in Europe, and by ACMA RALI FX 3Appendix 11 in Australia.
Prior antenna signal pattern backlobe suppression techniques include adding a backlobe suppression ring to the radome, for example via metalizing of the radome periphery as disclosed in commonly ownedUS Utility Patent No. 7,138,958, titled "Reflector Antenna Radome with Backlobe Suppressor Ring and Method of Manufacturing" issued November 21, 2006 to Syed et al. However, the required metalizing operations may increase manufacturing complexity and/or cost, including elaborate coupling arrangements configured to securely retain the shroud upon the reflector dish without presenting undesired reflection edges, signal leakage paths and/or extending the overall size of the radome. Further, the thin metalized ring layer applied to the periphery of the radome may be fragile, requiring increased care to avoid damage during delivery and/or installation.
Reflectors employing castellated edge geometries to generate constructive interference of the edge diffraction components have also been shown to improve the F/B, for example as disclosed in commonly owned Canada Patent No.CA887303 "Backlobe Reduction in Reflector-Type Antennas" by Holtum et al. Such arrangements increase the overall diameter of the antenna, which may complicate radome attachment, packaging and installation.
The addition of a shroud to a reflector antenna improves the signal pattern generally as a function of the shroud length, but also similarly introduces significant costs as the increasing length of the shroud also increases wind loading of the reflector antenna, requiring a corresponding increase in the antenna and antenna support structure strength. Further, an interconnection between the shroud and a radome may introduce significant F/B degradation.
Aconventional band clamp 1 applied to retain aradome 3 upon thereflector dish 7 or shroud may introduce diffraction edges and/or signal leakage paths, for example as shown inFigure 1. Metal taping, RF gaskets or the like may be applied to reduce F/B degradation resulting from band clamp use. However, these materials and procedures increase manufacturing costs and/or installation complexity and may be of limited longterm reliability.
Competition in the reflector antenna market has focused attention on improving electrical performance and minimization of overall manufacturing, inventory, distribution, installation and maintenance costs. Therefore, it is an object of the invention to provide a reflector antenna that overcomes deficiencies in the prior art.
US 2011/140983 A1 discloses a band clamp for coupling a radome to a distal end of a reflector dish for improving the front to back ratio of a reflector antenna, the band clamp provided with an inward projecting proximal lip and an inward projecting distal lip. The distal lip is dimensioned with an inner diameter equal to or less than a reflector aperture of the reflector dish. The proximal lip is provided with a turnback region dimensioned to engage an outer surface of a signal area of the reflector dish in an interference fit. A width of the band clamp may be dimensioned, for example, between 0.8 and 1.5 wavelengths of an operating frequency.

Brief Description of the Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, where like reference numbers in the drawing figures refer to the same feature or element and may not be described in detail for every drawing figure in which they appear and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.

Figure 1 is a schematic enlarged cut-away side view of a conventional prior art band clamp radome and reflector dish interconnection, demonstrating an RF signal leakage path.
Figure 2 is a schematic isometric cut-away view of a reflector antenna with radome to reflector dish band clamp interconnection.
Figure 3 is a schematic partial cut-away side view of a radome to reflector dish band clamp interconnection.
Figure 4 is an enlarged cut-away side view of a first exemplary radome to reflector dish band clamp interconnection.
Figure 5 is a graph illustrating a range of exemplary band clamp distal lip inner diameter to reflector dish aperture ratios and their effect upon corresponding reflector antenna F/B over a range of operating frequencies.
Figure 6 is a graph illustrating a range of band clamp widths and their effect upon corresponding reflector antenna F/B.
Figure 7 is a graph comparing measured co-polar F/B performance related to RF signal leakage between conventional band clamp and presently disclosed "new" band clamp configurations.
Figure 8 is a graph comparing measured cross-polar F/B performance related to RF signal leakage between conventional band clamp and presently disclosed "new" band clamp configurations.
Figure 9 is a graph of measured co-polar radiation patterns of a 0.6m reflector antenna with a band clamp with a 1.1 wavelength width.
Figure 10 is a graph of measured cross-polar radiation patterns of a 0.6m reflector antenna with a band clamp with a 1.1 wavelength width.
Figure 11 is an enlarged cut-away side view of a second exemplary radome to reflector dish band clamp interconnection.
Figure 12 is an enlarged cut-away side view of a third exemplary radome to reflector dish band clamp interconnection, including a width ring.
Figure 13 is a graph comparing predicted F/B enhancement with a band clamp of width of 0.5 and 1.2 wavelengths.
Figure 14 is a graph of measured co-polar radiation patterns for a reflector antenna with a band clamp with a 0.5 wavelength width.
Figure 15 is a graph of measured cross-polar radiation patterns for a reflector antenna with a band clamp with a 0.5 wavelength width.
Figure 16 is a graph of measured co-polar radiation patterns for a reflector antenna with a band clamp with a 1.2 wavelength width.
Figure 17 is a graph of measured cross-polar radiation patterns for a reflector antenna with a band clamp with a 1.2 wavelength width.
Figure 18 is an enlarged cut-away side view of a third exemplary radome to reflector dish band clamp interconnection, including a width ring with radial outward bend.
Figure 19 is a graph comparing predicted F/B enhancement with a band clamp with a width ring configuration of between 0 and 60 degrees radial outward bend.
Figure 20 is an enlarged cut-away view of a reflector dish band clamp interconnection according to the invention, including a width ring with a protruding portion aligned parallel to a longitudinal axis of the reflector dish.
Figure 21 is an isometric view of a section of the band clamp ofFigure 20.
Figure 22 is an enlarged cut-away view of another reflector dish band clamp interconnection according to the invention, including a width ring with a protruding portion angled at 60 degrees with respect to a longitudinal axis of the reflector dish.
Figure 23 is an isometric view of the interconnection ofFigure 22.
Figure 24 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion angled at 60 degrees with respect to a longitudinal axis of the reflector dish, demonstrating a distal edge serration.
Figure 25 is an isometric view of the interconnection ofFigure 24.
Figure 26 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion angled at 60 degrees with respect to a longitudinal axis of the reflector dish, demonstrating a distal edge serration and an interference fit against the reflector dish via proximal lip inward bias.
Figure 27 is an isometric view of the interconnection ofFigure 26.
Figure 28 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion angled at 60 degrees with respect to a longitudinal axis of the reflector dish, demonstrating a distal edge castellation.
Figure 29 is an isometric view of the interconnection ofFigure 28.
Figure 30 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion angled at 60 degrees with respect to a longitudinal axis of the reflector dish, demonstrating an alternative distal edge castellation.
Figure 31 is an isometric view of the interconnection ofFigure 30.
Figure 32 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion forming a choke groove open to a distal end of reflector dish.
Figure 33 is an isometric view of the interconnection ofFigure 32.
Figure 34 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion forming a choke groove open to a distal end of reflector dish and an annular protrusion of the proximal lip contacting the reflector dish.
Figure 35 is an isometric view of the interconnection ofFigure 34.
Figure 36 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion forming two concentric choke grooves open to a distal end of reflector dish.
Figure 37 is an isometric view of the interconnection ofFigure 36.
Figure 38 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a width ring with a protruding portion forming two concentric choke grooves open to a distal end of reflector dish and interference fit against the reflector dish via proximal lip inward bias.
Figure 39 is an isometric view of the interconnection ofFigure 38.
Figure 40 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including an arc segment transition between the distal lip and the proximal lip.
Figure 41 is an isometric view of the interconnection ofFigure 40.
Figure 42 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including an arc segment transition between the distal lip and the proximal lip and an interference fit against the reflector dish via proximal lip inward bias.
Figure 43 is an isometric view of the interconnection ofFigure 42.
Figure 44 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a choke groove in the transition between the distal lip and the proximal lip, the choke groove open to the outer diameter.
Figure 45 is an isometric view of the interconnection ofFigure 44.
Figure 46 is an enlarged cut-away view of another exemplary reflector dish band clamp interconnection, including a choke groove in the transition between the distal lip and the proximal lip, the choke groove open to the outer diameter and an interference fit against the reflector dish via proximal lip inward bias.
Figure 47 is an isometric view of the interconnection ofFigure 46.
Figures 1 to 19 herein show illustrative examples which do not form part of the invention as claimed.

Detailed Description

As shown inFigures 2 and3, aband clamp 1 is generally operative to retain aradome 3 upon the opendistal end 5 of areflector dish 7, creating an environmental seal that protects thereflector dish 7,subreflector 9 and/or feed 11 of areflector antenna 13 from environmental fouling. In a first example best shown inFigure 4, theband clamp 1 is provided with inward facing distal andproximal lips 15, 17. Aturnback region 19 of theproximal lip 17 is dimensioned to engage theouter surface 21 of thesignal area 23 of thereflector dish 7. Theturnback region 19 may be applied, for example, as an outward bend prior to theinward end 25 of theproximal lip 17. As theband clamp 1 is tightened during interconnection of theradome 3 and thereflector dish 7, the diameter of theband clamp 1 is progressively reduced, driving theturnback region 19 against the convexouter surface 21 of thesignal area 23 of thereflector dish 7, into a uniform circumferential interference fit. As theband clamp 1 is further tightened, theturnback region 19 slides progressively inward along theouter surface 21 of thesignal area 23 of thereflector dish 7 toward the reflector dishproximal end 27. Thereby, thedistal lip 15 of theband clamp 1 also moves towards the reflector dishproximal end 27, securely clamping theradome 3 against thedistal end 5 of thereflector dish 7. Because the interference fit between theturnback region 19 and theouter surface 21 of thereflector dish 7 is circumferentially uniform, any RF leakage between these surfaces is reduced.
Although it is possible to apply extended flanges to thereflector dish 7 and/orradome 3, these may unacceptably increase the overall size of thereflector antenna 1, which may negatively impact wind loading, material requirements, inventory and transport packaging requirements. Therefore, flanges of a reduced size, dimensioned to provide secure mechanical interconnection, may be applied. Theradome 3 may be provided with a greater diameter than thereflector dish 7, anannular lip 29 of the radome periphery mating with an outer diameter of thedistal end 5 of thereflector dish 7, keying theradome 3 coaxial with thereflector dish 7 and providing surface area for spacing theband clamp 1 from thesignal area 23 of thereflector dish 7.
The flanges may be dimensioned and theband clamp 1 similarly dimensioned such that thedistal lip 15 of theband clamp 1 is even with or extends slightly inward of a reflector aperture H, defined as the largest diameter of the reflector dish surface upon which signal energy is distributed by thesubreflector 9, to form a band clamp inner diameter D. To minimize diffraction and/or scatter signal components at the band clampdistal lip 15, the band clamp inner diameter D may be dimensioned with respect to reflector aperture H, resulting in significant F/B enhancement as illustrated inFigure 5. For reduced F/B in areflector antenna 13 of minimal overall diameter, a D/H ratio of 0.97-1.0 may be applied.
Referring again toFigure 4, another dimension of theband clamp 1 impacting the F/B is theband clamp 1 width "A" which determines the distance between band clamp outer corner(s) 31 acting as diffraction/scatter surfaces. As shown inFigure 6, normalized F/B is improved when the width "A" is between 0.8 and 1.5 wavelengths of the operating frequency, which can be operative to generate mutual interference of surface currents traveling along the band clamp outer periphery and/or scatter interference.
The significant improvement in measured F/B performance in a 0.6 meter reflector antenna configurations for both co-polar and cross-polar responses with a conventional priorart band clamp 1 and the and clamp configuration offigure 4 are illustrated inFigures 7 and8.Figures 9 and10 illustrate measured backlobe levels of co-polar and cross-polar radiation patterns in the 26 GHz band within the regulatory envelopes at greater than 71 dB with the band clamp configuration shown inFigure 4, in which the width "A" is equal to 1.1 wavelengths.
One skilled in the art will appreciate that the optimal range of widths "A" may be difficult to achieve for some operating frequencies without incorporating further structure in the radome and/or reflector dish periphery. For example, as shown inFigure 11, the width "A" may be increased via the application of afold 33 in the band clamp from the desired extent of the width "A" back toward thereflector dish 7. The pictured embodiment is simplified for demonstration purposes with respect to extending the width "A" but may similarly be applied with afold 33 andproximal lip 17 that extends further inward and includes aturnback region 19 contacting theouter surface 21 of thesignal area 23 of thereflector dish 7.
In an example shown inFigure 12, an extension of the width "A" may be cost effectively achieved by attaching afurther width ring 35 of metallic and/or metal coated material to theband clamp 1 outer diameter. Thewidth ring 35 may be applied with any desired width, cost effectively securely attached by spot welding or fasteners such as screws, rivets or the like.
Figure 13 illustrates 18 GHz band RF modeling software predictions of F/B improvement between awidth ring 35 width "A" of 0.5 and 1.2 wavelengths. Measured co-polar and cross-polar F/B performance of aFigure 12band clamp 1 withwidth ring 35 of width "A" = 0.5 wavelengths is shown inFigures 14 and15. Note the performance meets the regulatory envelope across the entire range, but with no margin. However, as shown inFigures 16 and17, the measured co-polar and cross-polar F/B performance of aFigure 12band clamp 1 withwidth ring 35 of width "A" = 1.2 wavelengths is significantly improved and well within the regulatory envelope throughout the entire range.
In another example, thewidth ring 35 may be provided in an angled configuration as demonstrated inFigure 18. As shown inFigure 19, RF modeling software predictions of F/B improvement indicate progressively increasing improvement as the angle applied increases from zero (flat width ring cross section) to sixty degrees of diffraction gradient.
In embodiments according to the invention, similar in electrical effect to thewidth ring 35 are formed integral with the band clamp cross section as a protrudingportion 37 of desired dimension. These complex structures may be cost efficiently formed with high precision via, for example, extrusion, injection molding, progressive punching and/or stretch forming. As shown for example inFigures 20-39, the protrudingportion 37 creates aband clamp 1 with a generally uniform cross section in which theproximal lip 17,distal lip 15 and protrudingportion 37 form a unitary contiguous portion. One skilled in the art will appreciate that the unitary contiguous portion simplifies manufacture by eliminating additional attachment steps and long term interconnection reliability concerns that may arise when separate elements such aswidth bands 35 are applied to theband clamp 1.
As shown for example inFigures 20 and 21, the protrudingportion 37 is provided extending from an outer diameter of theband clamp 1 parallel to a longitudinal axis of thereflector dish 7, effectively extending the width "A" of theband clamp 1 without requiring aseparate width band 35 as described herein above with respect toFigure 12. The protrudingportion 37 may be dimensioned, for example, such that the resulting band width "A" is a multiple of a quarter wavelength of a desired operating frequency of thereflector dish 7.
As shown in embodiments according to the invention inFigures 22 and 23, the protrudingportion 37 may be angled as described hereinabove with respect toFigures 18 and19. As modeled inFigure 19, the angle applied to the protrudingportion 37 may be, for example, 60 degrees with respect to a longitudinal axis of thereflector dish 7.
As shown for example inFigures 24-31, thedistal edge 39 of the protruding portion may be provided with a serration 41 (Figures 24-27) or a castellation 43 (Figures 28-31) to further inhibit backlobe generation at specific operating frequencies. Treatments of thedistal edge 39 to form the serration(s) 41 and/or castellation 43 may be applied as an additional fabrication step upon a uniform cross section band with protrudingportion 37, for example as shown inFigures 22 and 23, by stamping, cutting or the like to remove the desired portions of thedistal edge 39.
The protrudingportion 37 may also be dimensioned to extend from the outer diameter of theband clamp 1 to form at least onechoke groove 45 open to adistal end 5 of thereflector dish 7, for example as shown inFigures 32-35. In a trade-off with increased overall diameter of theband clamp 1, the number ofchoke grooves 45 may be increased. For example as shown inFigures 36-39,band clamp 1 may be provided with twoconcentric choke grooves 45.
The interference fit between theband clamp 1 and theouter surface 21 of thereflector dish 7 may be alternatively obtained by providing theproximal lip 17 with an inward bias, for example as shown inFigures 26, 27,34, 35,38, 39,42, 43,46 and 47. Thereby, the material requirements for theband clamp 1 may be reduced in a trade-off with ease of assembly. For ease of initial insertion, adistal sidewall 47 of theproximal lip 17 may be provided with anannular protrusion 49 which contacts thereflector dish 7, for example as shown inFigures 34 and 35. Thereby, theinward end 25 operates as an assembly guide for theband clamp 1 over thereflector dish 7 andradome 3, prior to engaging the interference fit as theband clamp 1 is inserted far enough for theannular protrusion 49 to enage thereflector dish 7 in the interference fit.
As shown for example inFigures 40-43, theband clamp 1 may be dimensioned with a transition between thedistal lip 15 and theproximal lip 17 formed as a continuous arc segment 51. Thereby, a material stress applied to the transition to create the bias between thedistal lip 15 and theproximal lip 17 against thereflector dish 7 may be distributed across a larger portion of material, instead of being concentrated in theouter corners 31 demonstrated in the other embodiments.
As shown for example inFigures 44-47, the outer diameter of the band clamp 1 (the transition between thedistal lip 15 and the proximal lip 17) may be provided with achoke groove 45 open to the outer diameter of theband clamp 1. Thereby, both an improved spring bias between thedistal lip 15 and theproximal lip 17 against thereflector dish 7 and an electrical performance improvement may be obtained.

One skilled in the art will appreciate that in addition to improving the electrical performance of thereflector antenna 13, the disclosedband clamp 1 can enable significant manufacturing, delivery, installation and/or maintenance efficiencies. Because theband clamp 1 enables simplified radome and reflector dish periphery geometries, the resultingreflector antenna 13 may have improved materials and manufacturing costs. Because theband clamp 1 is simply and securely attached, installation and maintenance may be simplified compared to prior reflector antenna configurations with complex peripheral geometries, delicate back lobe suppression ring coatings, platings and/or RF absorbing materials. Because theband clamp 1 may be compact and applied close to the reflector antenna aperture H, the overall diameter of thereflector antenna 13 may be reduced, which can reduce the reflector antenna wind loading characteristics and the required packaging dimensions. Where theband clamp 1 is fabricated utilizing extrusion, injection molding, progressive punching and/or stretch forming,complex band clamp 1 cross sections providing additional electrical performance may be provided in the form of a protrudingportion 37 with specific geometries, without requiring separate elements with additional attachment and/or reliability concerns.

Table ofParts

1	band clamp
3	radome
5	distal end
7	reflector dish
9	subreflector
11	feed
13	reflector antenna
15	distal lip
17	proximal lip
19	turnback region
21	outer surface
23	signal area
25	inward end
27	proximal end
29	annular lip
31	outer corner
33	fold
35	width ring
37	protrudingportion
39	distal edge
41	serration
43	castellation
45	choke groove
47	distal sidewall
49	annular protrusion
51	arc segment

Where in the foregoing description reference has been made to materials, ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art.

Claims

A band clamp (1) configured to couple a radome (3) to a distal end (5) of a reflector dish (7), the band clamp comprising:
a band with an inward projecting proximal lip (17) connected via a width portion (A) to an inward projecting distal lip (15);
and
a protruding portion (37) extending from the width portion (A) of the band clamp (1) at a side of the proximal lip (17) and configured to improve a front to back ratio, F/ B, of a reflector antenna comprising the reflector dish (7);
wherein the distal lip (15) is dimensioned with an inner diameter less than or equal to a reflector aperture of the reflector dish (7);
wherein the proximal lip (17) is dimensioned to engage an outer surface of the reflector dish (7) in an interference fit; and
characterized in
that the proximal lip (17), distal lip (15), and the protruding portion (37) form a unitary contiguous portion; and
that the protruding portion (37) extends a width of the width portion of the band clamp.
The band clamp of claim 1, wherein the proximal lip is provided with a turnback region (19) dimensioned to engage an outer surface (21) of a signal area (23) of the reflector dish (7).
The band clamp of claim 1, wherein a distal edge (39) of the protruding portion is serrated (41).
The band clamp of claim 1, wherein a distal edge (39) of the protruding portion is castellated (43).
The band clamp of claim 1, wherein the protruding portion (37) extends toward a proximal end (27) of the reflector dish (7).
The band clamp of claim 1, wherein the protruding portion (37) has a length dimensioned as a multiple of one quarter wavelength of a desired operating frequency of the reflector dish (7).
The band clamp of claim 1, wherein the protruding portion (37) extends outward at an angle of approximately 60 degrees from a longitudinal axis of the reflector dish (7).
The band clamp of claim 1, wherein the protruding portion (37) extends from an outer diameter of the band clamp; the protruding portion forming at least one choke groove (45) open to the distal end (5) of the reflector dish (7).
The band clamp of claim 8, wherein a width of the at least one choke groove (45) is dimensioned as a multiple of one quarter wavelength of a desired operating frequency of the reflector dish (7).
The band clamp of claim 8, wherein the at least one choke groove (45) is two concentric choke grooves.
The band clamp of claim 1, wherein a choke groove (45) open to an outer diameter of the band is provided in an outer diameter of the band.
A method for manufacturing a band clamp (1) configured to couple a radome (3) to a distal end (5) of a reflector dish (7), comprising the steps of:
forming a band with an inward projecting proximal lip (17), connected via a width portion (A) to an inward projecting distal lip (15), and a protruding portion (37) extending from the width portion (A) of the band clamp (1) at a side of the proximal lip (17);
wherein the distal lip is dimensioned with an inner diameter less than or equal to a reflector aperture of the reflector dish;
wherein the proximal lip (17) is dimensioned to engage an outer surface of the reflector dish (7) in an interference fit; B,
wherein the protruding portion is configured to improve a front to back ratio, F/ of a reflector antenna comprising the reflector dish (7); and
characterized in
that the proximal lip (17), distal lip (15), and the protruding portion (37) are formed as a unitary contiguous portion; and
that the protruding portion (37) extends a width of the width portion of the band clamp.
The method of claim 12, wherein the band is formed by extrusion.
The method of claim 12, wherein the band is formed by stretch forming.