EP0346105A2 - Spacecraft antenna system - Google Patents

Spacecraft antenna system Download PDF

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Publication number
EP0346105A2
EP0346105A2 EP19890305766 EP89305766A EP0346105A2 EP 0346105 A2 EP0346105 A2 EP 0346105A2 EP 19890305766 EP19890305766 EP 19890305766 EP 89305766 A EP89305766 A EP 89305766A EP 0346105 A2 EP0346105 A2 EP 0346105A2
Authority
EP
European Patent Office
Prior art keywords
sub
antenna system
reflector
reflectors
coverage area
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19890305766
Other languages
German (de)
French (fr)
Other versions
EP0346105A3 (en
Inventor
Simon John Stirland
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems PLC
Original Assignee
British Aerospace PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Aerospace PLC filed Critical British Aerospace PLC
Publication of EP0346105A2 publication Critical patent/EP0346105A2/en
Publication of EP0346105A3 publication Critical patent/EP0346105A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • H01Q19/18—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces
    • H01Q19/19—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/192—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface with dual offset reflectors

Definitions

  • This invention relates to a spacecraft antenna system capable of passing radiation to or from more than one coverage area.
  • a spacecraft antenna system capable of passing radiation to or from more than one coverage area, characterised by including feed means, a single shaped main reflector and at least two shaped sub-reflectors which are operable simultaneously, one for each coverage area.
  • the system has two shaped sub-reflectors and the feed means provides two feeds, one for each said sub-reflector.
  • a spacecraft antenna system of the invention as shown in Figure 1 of the accompanying drawings has feed means, a single shaped main reflector 3 and at least two, in this case only two, shaped sub-reflectors 4,5.
  • the shaped reflector concept as disclosed in our European Patent Application No. 219321 and our co-pending UK Patent Application No. 8813655-1 of even date herewith is used to shape the main reflector 3 and two sub-reflectors 4,5.
  • the feed means provides two feeds 6 and 7, with the feed 6 and sub-reflector 4 providing the coverage area 1 of Figure 2 and with the feed 7 and sub-reflector 5 providing the coverage area 2 of Figure 2.
  • the feeds 6,7 and sub-reflectors 4,5 are operable simultaneously.
  • the antenna system has two feeds rather than about 140 which would be needed for a multiple feed unshaped single reflector antenna of the same diameter.
  • the sub-reflectors 4,5 may alternatively be mounted side by side, i.e. along a line perpendicular to the plane of Figure 1, or alternatively separated in any direction to enable the antenna system to be mounted most conveniently on a spacecraft.
  • the shaped reflector optimisation technique used is based on iterative use of analysis software within a standard minimax algorithm. Essentially any parameter describing an antenna system may be optimised in an attempt to drive the antenna gains, evaluated at the set of observations points, towards a specified target template.
  • the optimisation parameters are sets of biharmonic distortions on all three reflectors. At each iteration both dual reflector systems are analysed in order to compare the two sets of gains with the target values. There are over 100 optimisation variables.
  • This optimisation procedure allows suppression of gain in specified regions as well as enhancement in others.

Abstract

A spacecraft antenna system has feed means, preferably two separate feeds (6,7), a single shaped main reflector (3) and at least two, preferably two, shaped sub-reflectors (4,5) which are operable simultaneously to provide coverage to or from more than one coverage area. One sub-reflector (4,5) thus covers one specific coverage area.

Description

  • This invention relates to a spacecraft antenna system capable of passing radiation to or from more than one coverage area.
  • Obtaining several (specifically two) non-identical antenna patterns from a single antenna has previously required the very large number of feeds associated with a multiple beam antenna technique.
  • There is thus a need for a generally improved and simpler antenna system for applications where several coverages are required from a single antenna, and where it is not required to change the individual pattern shapes while the satellite is in orbit. A good example is the INTELSAT hemi coverages of Earth, as shown in the accompanying Figure 2 in which it is necessary to cover areas 1 and 2 as bounded by lines 1a and 2a respectively. In the past such patterns could only be obtained from multi-feed antennas system, at the cost of greater mass, microwave losses and mechanised complexity.
  • According to the present invention there is provided a spacecraft antenna system capable of passing radiation to or from more than one coverage area, characterised by including feed means, a single shaped main reflector and at least two shaped sub-reflectors which are operable simultaneously, one for each coverage area.
  • Preferably the system has two shaped sub-reflectors and the feed means provides two feeds, one for each said sub-reflector.
  • For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-
    • Figure 1 is a diagrammatic side view of a spacecraft antenna system according to the present invention, and
    • Figure 2 is a general view of the planet Earth showing two coverage areas.
  • A spacecraft antenna system of the invention, as shown in Figure 1 of the accompanying drawings has feed means, a single shaped main reflector 3 and at least two, in this case only two, shaped sub-reflectors 4,5.
  • In this invention, the shaped reflector concept, as disclosed in our European Patent Application No. 219321 and our co-pending UK Patent Application No. 8813655-1 of even date herewith is used to shape the main reflector 3 and two sub-reflectors 4,5.
  • In the example illustrated in Figure 1 the feed means provides two feeds 6 and 7, with the feed 6 and sub-reflector 4 providing the coverage area 1 of Figure 2 and with the feed 7 and sub-reflector 5 providing the coverage area 2 of Figure 2. The feeds 6,7 and sub-reflectors 4,5 are operable simultaneously. Thus the antenna system has two feeds rather than about 140 which would be needed for a multiple feed unshaped single reflector antenna of the same diameter.
  • The sub-reflectors 4,5 may alternatively be mounted side by side, i.e. along a line perpendicular to the plane of Figure 1, or alternatively separated in any direction to enable the antenna system to be mounted most conveniently on a spacecraft.
  • The shaped reflector optimisation technique used is based on iterative use of analysis software within a standard minimax algorithm. Essentially any parameter describing an antenna system may be optimised in an attempt to drive the antenna gains, evaluated at the set of observations points, towards a specified target template. In this case the optimisation parameters are sets of biharmonic distortions on all three reflectors. At each iteration both dual reflector systems are analysed in order to compare the two sets of gains with the target values. There are over 100 optimisation variables.
  • This optimisation procedure allows suppression of gain in specified regions as well as enhancement in others.

Claims (2)

1. A spacecraft antenna system capable of passing radiation to or from more than one coverage area, characterized by including feed means (6,7), a single shaped main reflector (3) and at least two shaped sub-reflectors (4,5) which are operable simultaneously, one for each coverage area.
2. A system according to claim 1, having two shaped sub-reflectors (4,5) and wherein the feed means provides two feeds (6,7), one for each said sub-reflector (4,5).
EP19890305766 1988-06-09 1989-06-07 Spacecraft antenna system Withdrawn EP0346105A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8813656 1988-06-09
GB888813656A GB8813656D0 (en) 1988-06-09 1988-06-09 Spacecraft antenna system

Publications (2)

Publication Number Publication Date
EP0346105A2 true EP0346105A2 (en) 1989-12-13
EP0346105A3 EP0346105A3 (en) 1991-07-03

Family

ID=10638349

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890305766 Withdrawn EP0346105A3 (en) 1988-06-09 1989-06-07 Spacecraft antenna system

Country Status (2)

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EP (1) EP0346105A3 (en)
GB (1) GB8813656D0 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6603437B2 (en) * 2001-02-13 2003-08-05 Raytheon Company High efficiency low sidelobe dual reflector antenna

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4298877A (en) * 1979-01-26 1981-11-03 Solar Energy Technology, Inc. Offset-fed multi-beam tracking antenna system utilizing especially shaped reflector surfaces
GB2098806A (en) * 1981-04-27 1982-11-24 Kokusai Denshin Denwa Co Ltd Multiple reflector antenna
US4591866A (en) * 1983-02-04 1986-05-27 Kokusai Denshin Denwa Kabushiki Kaisha Multi-beam antenna and its configuration process
EP0219321A1 (en) * 1985-10-10 1987-04-22 British Aerospace Public Limited Company Antenna systems

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4298877A (en) * 1979-01-26 1981-11-03 Solar Energy Technology, Inc. Offset-fed multi-beam tracking antenna system utilizing especially shaped reflector surfaces
GB2098806A (en) * 1981-04-27 1982-11-24 Kokusai Denshin Denwa Co Ltd Multiple reflector antenna
US4591866A (en) * 1983-02-04 1986-05-27 Kokusai Denshin Denwa Kabushiki Kaisha Multi-beam antenna and its configuration process
EP0219321A1 (en) * 1985-10-10 1987-04-22 British Aerospace Public Limited Company Antenna systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6603437B2 (en) * 2001-02-13 2003-08-05 Raytheon Company High efficiency low sidelobe dual reflector antenna

Also Published As

Publication number Publication date
EP0346105A3 (en) 1991-07-03
GB8813656D0 (en) 1988-07-13

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