Title of Invention	"REFLECTOR ANTENNA RADOME WITH BACKLOBE SUPPRESSOR RING AND METHOD OF MANUFACTURING"
Abstract	A radome adapted to reduce backlobes of an associated reflector antenna via application of a conductive ring with an inward facing edge about the periphery of the radome. The conductive ring may be appiied extending around the radome periphery to an inside and or outside surface of the radome. The conductive ring may be formed upon the radome by metalising, electrodaging, over molding or the like. Further, the conductive ring may be a metal, metallic foii, conductive foam or the like which is coupled to the radome. An absorber in the form of a ring or a surface coating appiied to the radome and or the distal end of the reflector may also be added between the radome and the reflector.

Title of Invention

"REFLECTOR ANTENNA RADOME WITH BACKLOBE SUPPRESSOR RING AND METHOD OF MANUFACTURING"

Abstract

A radome adapted to reduce backlobes of an associated reflector antenna via application of a conductive ring with an inward facing edge about the periphery of the radome. The conductive ring may be appiied extending around the radome periphery to an inside and or outside surface of the radome. The conductive ring may be formed upon the radome by metalising, electrodaging, over molding or the like. Further, the conductive ring may be a metal, metallic foii, conductive foam or the like which is coupled to the radome. An absorber in the form of a ring or a surface coating appiied to the radome and or the distal end of the reflector may also be added between the radome and the reflector.

Full Text	REFLECTOR ANTENNA RADOME WITH SUPPRESSOR RING AND METHOD OF MANUFACTURING BACKGROUND OF INVENTION Field of the Invention This invention relates to reflector antenna radomes. More particularly, the invention relates to a reflector antenna radome with a backlobe suppression ring around the radome periphery Description of Related Art The front to back (F/B) ratio of a reflector antenna indicates the proportion of the maximum antenna signal that is radiated in any backward directions relative to the main beam, across the operating bând. Rearward signal patterns, also known as backlobes, are generated by edge diffraction occurring at the periphery of the reflector dish. Where significant backlobes are generated, signal interference with other RF systems may occur and overall antenna efficiency is reduced. Local and internaţional standards groups have defined acceptable F/B ratios for various RF operating frequency bands. Prior reflector antennas have used a range of different solutions to maintain an acceptable F/B ratio. For example, conical RF shields which extend forward of the reflector may be applied. However, shield structures increase the overall size, wind load and thereby structural requirements of the antenna, increasing overall antenna and antenna support structure costs. Edge profiling, chokes and or reflector edge notching/serration patterns have been formed in and or applied to the reflector dish periphery. However, these structures, in addition to significantly increasing the manufacturing costs of the resulting antenna, increase antenna wind loading and are typically optimized for a specific frequency bând which limits the available market segments for each specific reflector dish design, decreasing manufacturing efficiencies. F/B ratio is especially significant in modern shield less deep dish reflectors. Deep dish reflectors, by having a low focal length to reflector dish diameter ratio, may be formed with increased aperture efficiency and low side lobes without requiring peripheral shielding. However, to achieve these radiation patterns, the edges of the deep dish reflectors are designed to have higher signal illumination levels relative to shallow dish designs, increasing reflector edge diffraction and thereby generating significant backlobes. Competition within the reflector antenna industry has focused attention on RF signal pattern optimization, structural integrity, as well as materials and manufacturing operations costs. Also, increased manufacturing efficiencies, via standardized reflector antenna components usable in configurations adaptable for multiple frequency bands is a growing consideration in the reflector antenna market. Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated in and constituie a part of this specification, illustrate embodiments of the invention 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 cut-away side view of a reflector antenna with a radome according to one embodiment of the invention Figure 2 is a close-up view of area A of Figure 1. Figure 3 is an isometric view of the radome of Figure showing the front surface and side edge. Figures 4a and 4b are charts demonstrating comparative measured signal radiation patterns, in h and e planes respectively, of a reflector antenna operating at 12. 7GHz with and without a backlobe suppression ring according to the invention. Figure 5 is a chart demonstrating comparative measured signal radiation patterns of a reflector antenna operating at 21.2GHz with and without a backlobe suppression ring according to the invention. DETAILED DESCRIPTION The invention is described in an exemplary embodiment applied upon a radome also having quick attach/detach features further described in US utility patent application serial number 10/604, Radius Twist Lock Radome and Reflector Antenna for Radome", Syed et al, filed August 14,2003 and hereby incorporated by reference in the entirety. The invention is described herein with respect to a single profile radome. One skilled in the art will appreciate that the invention may also be applied, for example, to the dual radius radome configurations disclosed in the aforementioned application. As shown in Figure a typical deep dish reflector antenna 1 projects a signal from a feed 3 upon a sub reflector 5 which reflects the signal to illuminate the reflector 7. A radome 9 covers the open distal end of the reflector 7 to form an environmental seal and reduce the overall wind load of the antenna 1. As shown in Figures 2 and 3, a conductive ring herein after identified as a backlobe suppression ring (BSR) is formed around the radome 9 periphery. The BSR may be formed, for example, by metalising, or over molding the edge of the radome 9. Alternatively, the BSR may be formed by coupling a BSR formed of, for example, conductive rubber, metal, metallic foii, metallic tape or the like, about the radome 9 periphery. The conductive ring forming the BSR need not be continuous and or interconnected around the radome circumference, for example, the conductive ring may be formed as electrically isolated segments arranged around the periphery. As shown in greater detail in Figure 2, where metalising or the like is used about the radome 9 periphery, the BSR 11 may be cost efficiently formed surrounding the inside 13 and the outside 15 of the radome 9 periphery. Preferably, the BSR is in electrical contact with the reflector 7 periphery. Thereby, electrica! gaps and or slots through which RF energy may pass to diffract from the reflector 7 outer edge are avoided. The radome 9 has an outer diameter adapted to enable coupling of the radome 9 upon the distal open end of the reflector 7. The BSR formed about the outer surface of the radome periphery does not significantly increase the radome outer diameter. Therefore, the addition of the BSR to the radome 9 does not significantly add to the antenna 1 wind load. Also, because the BSR 11 may be as formed as a thin metalised layer, it does not significantly increase weight and therefore the structural requirements of the antenna 1 or antenna 1 support structures. In operation, RF signals which would otherwise edge diffract rearward at the outward facing reflector 7 edge are instead trapped by the generally radially inward facing radome 9 outer 15 surface and or inner 13 surface edge (s) of the BSR Due to the inward facing edge (s) 16 presented by the BSR backwards edge diffracted energy overall is significantly reduced. Contrary to prior frequency specified serrated, notched or choke reflector edge configurations, the BSR may be applied without complex or precise design of the BSR geometry. A general limit of the BSR inner radius is that the BSR should not project inward to a point where it will significantly interfere with the forward beam pattern of the antenna 1, for example extending inward not substantially than an inner diameter of the reflector 7 distal end. To further minimize spill over in forward hemisphere, an absorber 17 may be applied between the radome 9 and the reflector 7. The absorber 17 may be formed from an RF absorbing material and or an RF absorbing coating applied to the radome 9 and or the reflector 7 periphery. Measured test range data, as shown in Figures 4a and 4b obtained from 1 foot diameter deep dish reflector antennas configured for operation at 12.7 GHz demonstrates the significant reduction generated by the present invention. The axial identified by the right and left edges of the e-plane and h- plane radiation patterns shown, are reduced by more than 10 dB through the addition of the BSR to the radome 9. Further, the aperture control of the antenna, outside of approximately plus or minus 80 degrees, is also significantly improved. The antenna of figures 4a and 4b has an outside surface BSR 11 with a width, measured from the radome 9 periphery towards the radome 9 center, of 22 mm. Similarly, Figure 5 shows test data from the same reflector and radome profile (different feed assembly) operating at 21.2 GHz. This antenna 1 has an outside 15 surface BSR with a width of 15 mm. Because the antennas of Figures 4a, 4b and 5 are able to gain the benefit of the present invention while using the same basic reflector dish and radome profile (but different feed assemblies) there is a significant manufacturing economy.The present invention brings to the art a radome which cost efficiently improves the F/B ratio of an antenna. The invention may be applied to new or existing antennas without significantly increasing the antenna weight and or wind load characteristics. The invention provides F/B ratio improvement independent of antenna operating frequency and does not place any additional requirements upon the design and or manufacture of the reflector 7 dish. (Table Removed) Where in the foregoing description reference has been made to ratios, integers, components or modules 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. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims. WE CLAIM 1. A radome with a front/back ratio reduction characteristic for a reflector antenna, comprising: a radome in contact with a conductive ring having an inward facing edge proximate a periphery of the radome; the inward facing edge extending inward along the radome at least to an inner diameter of a distal end of a main reflector of the reflector antenna. 2. The apparatus of claim 1, wherein the conductive ring extends from an inside surface to an outside surface, around a periphery of the radome. 3. The apparatus of claim 1, wherein the conductive ring is orie of metalised, electrodaged, and over molded upon the radome. 4. The apparatus of claim 1, wherein the conductive ring is one of metal, metallic foii, adhesive foii and a conductive rubber coupled to the radome. 5. The apparatus of claim 1, wherein the conductive ring is a plurality of electrically isolated segments. 6. The apparatus of claim 1, further including an absorber coupled to the inside of the radome periphery. 7. The apparatus of claim 7, wherein the absorber is one of a foam ring and an absorbing surface coating. 8. The apparatus of claim 2, wherein the conductive ring on the outside surface has a smaller inner diameter than the conductive ring on the inside surface. 9. A method for reducing the front / back ratio of a reflector antenna, comprising the steps of: coupling a conductive ring having an inward facing edge to a periphery of a radome of the reflector antenna; the inward facing edge extending inward along the radome at least to an inner diameter of a distal end of a main reflector of the reflector antenna. 10. The method of claim 10, wherein the conductive ring is coupled to the radome by one of metalising, electrodaging, and over molding. 11. The method of claim 10, wherein the conductive ring is formed from a plurality of electrically isolated segments. 12. The method of claim 10, wherein the conductive ring is coupled to the conductive ring whereby it extends around the periphery from an inside surface to an outside surface. 13. The method of claim 13, wherein the conductive ring on the outside surface has a smaller inner diameter than the conductive ring on the inside surface. 14. A reflector antenna with a front/back ratio reduction characteristic, comprising: a sub reflector positioned to redirect an RF signal from a feed to illuminate a reflector; a radome adapted to cover an open distal end of the reflector; and a conductive ring coupled to the radome, the conductive ring having an inward facing edge extending inward along the radome at least to an inner diameter of a distal end of the reflector proximate a periphery of the radome. The apparatus of claim 15, wherein the conductive ring extends from an inside surface to an outside surface, around a periphery of the radome. 15. The apparatus of claim 15, wherein the conductive ring has an inner diameter proximate an inner diameter of a reflector dish open end. 16. The apparatus of claim 15, wherein the conductive ring is one of metalised, electrodaged, and over molded upon the radome. 17. The apparatus of claim 15, wherein the conductive ring is one of metal, metallic foii, adhesive foii and a conductive rubber coupled to the radome.

Full Text

REFLECTOR ANTENNA RADOME WITH SUPPRESSOR RING AND METHOD OF MANUFACTURING
BACKGROUND OF INVENTION
Field of the Invention
This invention relates to reflector antenna radomes. More particularly, the invention relates to a reflector antenna radome with a backlobe suppression ring around the radome periphery
Description of Related Art
The front to back (F/B) ratio of a reflector antenna indicates the proportion of the maximum antenna signal that is radiated in any backward directions relative to the main beam, across the operating bând. Rearward signal patterns, also known as backlobes, are generated by edge diffraction occurring at the periphery of the reflector dish. Where significant backlobes are generated, signal interference with other RF systems may occur and overall antenna efficiency is reduced. Local and internaţional standards groups have defined acceptable F/B ratios for various RF operating frequency bands.
Prior reflector antennas have used a range of different solutions to maintain an acceptable F/B ratio. For example, conical RF shields which extend forward of
the reflector may be applied. However, shield structures increase the overall size, wind load and thereby structural requirements of the antenna, increasing overall antenna and antenna support structure costs. Edge profiling, chokes and or reflector edge notching/serration patterns have been formed in and or applied to the reflector dish periphery. However, these structures, in addition to significantly increasing the manufacturing costs of the resulting antenna, increase antenna wind loading and are typically optimized for a specific frequency bând which limits the available market segments for each specific reflector dish design, decreasing manufacturing efficiencies.
F/B ratio is especially significant in modern shield less deep dish reflectors. Deep dish reflectors, by having a low focal length to reflector dish diameter ratio, may be formed with increased aperture efficiency and low side lobes without requiring peripheral shielding. However, to achieve these radiation patterns, the edges of the deep dish reflectors are designed to have higher signal illumination levels relative to shallow dish designs, increasing reflector edge diffraction and thereby generating significant backlobes.
Competition within the reflector antenna industry has focused attention on RF signal pattern optimization, structural integrity, as well as materials and manufacturing operations costs. Also, increased manufacturing efficiencies, via standardized reflector antenna components usable in configurations adaptable
for multiple frequency bands is a growing consideration in the reflector antenna
market.
Therefore, it is an object of the invention to provide an apparatus that overcomes
deficiencies in the prior art
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated in and constituie a part of this specification, illustrate embodiments of the invention 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 cut-away side view of a reflector antenna with a radome according to one embodiment of the invention
Figure 2 is a close-up view of area A of Figure 1.
Figure 3 is an isometric view of the radome of Figure showing the front surface and side edge.
Figures 4a and 4b are charts demonstrating comparative measured signal radiation patterns, in h and e planes respectively, of a reflector antenna operating
at 12. 7GHz with and without a backlobe suppression ring according to the invention.
Figure 5 is a chart demonstrating comparative measured signal radiation patterns of a reflector antenna operating at 21.2GHz with and without a backlobe suppression ring according to the invention.
DETAILED DESCRIPTION
The invention is described in an exemplary embodiment applied upon a radome also having quick attach/detach features further described in US utility patent application serial number 10/604, Radius Twist Lock Radome and Reflector Antenna for Radome", Syed et al, filed August 14,2003 and hereby incorporated by reference in the entirety. The invention is described herein with respect to a single profile radome. One skilled in the art will appreciate that the invention may also be applied, for example, to the dual radius radome configurations disclosed in the aforementioned application.
As shown in Figure a typical deep dish reflector antenna 1 projects a signal from a feed 3 upon a sub reflector 5 which reflects the signal to illuminate the reflector 7. A radome 9 covers the open distal end of the reflector 7 to form an environmental seal and reduce the overall wind load of the antenna 1.
As shown in Figures 2 and 3, a conductive ring herein after identified as a backlobe suppression ring (BSR) is formed around the radome 9 periphery. The BSR may be formed, for example, by metalising, or over molding the edge of the radome 9. Alternatively, the BSR may be formed by coupling a BSR formed of, for example, conductive rubber, metal, metallic foii, metallic tape or the like, about the radome 9 periphery. The conductive ring forming the BSR need not be continuous and or interconnected around the radome circumference, for example, the conductive ring may be formed as electrically isolated segments arranged around the periphery.
As shown in greater detail in Figure 2, where metalising or the like is used about the radome 9 periphery, the BSR 11 may be cost efficiently formed surrounding the inside 13 and the outside 15 of the radome 9 periphery. Preferably, the BSR is in electrical contact with the reflector 7 periphery. Thereby, electrica! gaps and or slots through which RF energy may pass to diffract from the reflector 7 outer edge are avoided.
The radome 9 has an outer diameter adapted to enable coupling of the radome 9 upon the distal open end of the reflector 7. The BSR formed about the outer surface of the radome periphery does not significantly increase the radome outer diameter. Therefore, the addition of the BSR to the radome 9 does not significantly add to the antenna 1 wind load. Also, because the BSR 11 may be as formed as a thin metalised layer, it does not significantly increase weight and
therefore the structural requirements of the antenna 1 or antenna 1 support structures.
In operation, RF signals which would otherwise edge diffract rearward at the outward facing reflector 7 edge are instead trapped by the generally radially inward facing radome 9 outer 15 surface and or inner 13 surface edge (s) of the BSR Due to the inward facing edge (s) 16 presented by the BSR backwards edge diffracted energy overall is significantly reduced.
Contrary to prior frequency specified serrated, notched or choke reflector edge configurations, the BSR may be applied without complex or precise design of the BSR geometry. A general limit of the BSR inner radius is that the BSR should not project inward to a point where it will significantly interfere with the forward beam pattern of the antenna 1, for example extending inward not substantially than an inner diameter of the reflector 7 distal end. To further minimize spill over in forward hemisphere, an absorber 17 may be applied between the radome 9 and the reflector 7. The absorber 17 may be formed from an RF absorbing material and or an RF absorbing coating applied to the radome 9 and or the reflector 7 periphery.
Measured test range data, as shown in Figures 4a and 4b obtained from 1 foot diameter deep dish reflector antennas configured for operation at 12.7 GHz demonstrates the significant reduction generated by the present invention.
The axial identified by the right and left edges of the e-plane and h- plane radiation patterns shown, are reduced by more than 10 dB through the addition of the BSR to the radome 9. Further, the aperture control of the antenna, outside of approximately plus or minus 80 degrees, is also significantly improved. The antenna of figures 4a and 4b has an outside surface BSR 11 with a width, measured from the radome 9 periphery towards the radome 9 center, of 22 mm.
Similarly, Figure 5 shows test data from the same reflector and radome profile (different feed assembly) operating at 21.2 GHz. This antenna 1 has an outside 15 surface BSR with a width of 15 mm. Because the antennas of Figures 4a, 4b and 5 are able to gain the benefit of the present invention while using the same basic reflector dish and radome profile (but different feed assemblies) there is a significant manufacturing economy.The present invention brings to the art a radome which cost efficiently improves the F/B ratio of an antenna. The invention may be applied to new or existing antennas without significantly increasing the antenna weight and or wind load characteristics. The invention provides F/B ratio improvement independent of
antenna operating frequency and does not place any additional requirements upon the design and or manufacture of the reflector 7 dish.

(Table Removed) Where in the foregoing description reference has been made to ratios, integers, components or modules 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. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.

WE CLAIM
1. A radome with a front/back ratio reduction characteristic for a reflector
antenna,
comprising:
a radome in contact with a conductive ring having an inward facing edge
proximate a periphery of
the radome;
the inward facing edge extending inward along the radome at least to an
inner diameter of a distal
end of a main reflector of the reflector antenna.
2. The apparatus of claim 1, wherein the conductive ring extends from an
inside surface to an outside surface, around a periphery of the radome.
3. The apparatus of claim 1, wherein the conductive ring is orie of metalised,
electrodaged, and over molded upon the radome.
4. The apparatus of claim 1, wherein the conductive ring is one of metal,
metallic foii, adhesive foii and a conductive rubber coupled to the radome.
5. The apparatus of claim 1, wherein the conductive ring is a plurality of
electrically isolated segments.
6. The apparatus of claim 1, further including an absorber coupled to the
inside of the radome periphery.
7. The apparatus of claim 7, wherein the absorber is one of a foam ring and
an
absorbing surface coating.
8. The apparatus of claim 2, wherein the conductive ring on the outside
surface has a smaller inner diameter than the conductive ring on the
inside
surface.
9. A method for reducing the front / back ratio of a reflector antenna,
comprising the steps of:
coupling a conductive ring having an inward facing edge to a periphery of
a radome of the
reflector antenna;
the inward facing edge extending inward along the radome at least to an
inner diameter of a distal
end of a main reflector of the reflector antenna.
10. The method of claim 10, wherein the conductive ring is coupled to the
radome by one of metalising, electrodaging, and over molding.
11. The method of claim 10, wherein the conductive ring is formed from a
plurality of electrically isolated segments.
12. The method of claim 10, wherein the conductive ring is coupled to the
conductive ring whereby it extends around the periphery from an inside
surface to an outside surface.
13. The method of claim 13, wherein the conductive ring on the outside
surface has a smaller inner diameter than the conductive ring on the
inside
surface.
14. A reflector antenna with a front/back ratio reduction characteristic,
comprising:
a sub reflector positioned to redirect an RF signal from a feed to
illuminate a reflector;
a radome adapted to cover an open distal end of the reflector; and
a conductive ring coupled to the radome, the conductive ring having an
inward facing edge
extending inward along the radome at least to an inner diameter of a distal
end of the reflector
proximate a periphery of the radome.
The apparatus of claim 15, wherein the conductive ring extends from an
inside surface to an outside surface, around a periphery of the radome.
15. The apparatus of claim 15, wherein the conductive ring has an inner
diameter proximate an inner diameter of a reflector dish open end.
16. The apparatus of claim 15, wherein the conductive ring is one of
metalised, electrodaged, and over molded upon the radome.
17. The apparatus of claim 15, wherein the conductive ring is one of metal,
metallic foii, adhesive foii and a conductive rubber coupled to the radome.

Documents:

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Patent Number

272550

Indian Patent Application Number

3945/DELNP/2006

PG Journal Number

15/2016

Publication Date

08-Apr-2016

Grant Date

07-Apr-2016

Date of Filing

07-Jul-2006

Name of Patentee

COMMSCOPE TECHNOLOGIES LLC

Applicant Address

1100 CommScope Place, SE Hickory, North Carolina 28602, United States of America

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. JUNAID SYED	1 BARRY ROAD KIRKCALDY, KY2 6HY UNITED KINGDOM.
2	ROY CAMPBELL	THE COACH HOUSE FERNIE CASTLE STABLES LADYBANK, FIFE KY 15 7RU UNITED KINGDOM.
3	DAVID SUTHERLAND	14 MAIN STREET LOWER LARGO, FIFE UNITD KINGDOM.

PCT International Classification Number

H01Q 1/42

PCT International Application Number

PCT/IB2005/000284

PCT International Filing date

2005-02-03

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10/708,393	2004-02-27	U.S.A.