EP0219321A1 - Antennensystem - Google Patents

Antennensystem Download PDF

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Publication number
EP0219321A1
EP0219321A1 EP86307829A EP86307829A EP0219321A1 EP 0219321 A1 EP0219321 A1 EP 0219321A1 EP 86307829 A EP86307829 A EP 86307829A EP 86307829 A EP86307829 A EP 86307829A EP 0219321 A1 EP0219321 A1 EP 0219321A1
Authority
EP
European Patent Office
Prior art keywords
radiation
reflector
reflector surface
antenna
levels
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Withdrawn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
EP86307829A
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English (en)
French (fr)
Inventor
Philip C. British Aerospace Public Wilcockson
Robert H. British Aerospace Public Fairlie
David Dr. British Aerospace Public Robson
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 EP0219321A1 publication Critical patent/EP0219321A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/28—Adaptation for use in or on aircraft, missiles, satellites, or balloons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures
    • H01Q15/147—Reflecting surfaces; Equivalent structures provided with means for controlling or monitoring the shape of the reflecting surface

Definitions

  • This invention relates to antenna systems and is more particularly concerned with antenna systems which provide one or more area coverages of specified shapes for separate or simultaneous transmission and reception of signals.
  • the shaped reflector antenna There are three categories of antenna systems which produce such coverage: the shaped reflector antenna, the multibeam antenna and the phased array.
  • This invention relates specifically to improvements in shaped reflector systems, which have, according to the prior art, been used only for regular elliptical or moderately irregular coverage specifications. For complex coverage shapes the multiple beat antenna or phased array has been the generally preferred solution.
  • the multibeam antenna approach uses a parabolic reflector, and produces the shaped area coverage by using a cluster of similar feed elements positioned around the focal point of the reflector, thereby producing overlapping areas of spot coverage within the coverage area.
  • the phased array approach no reflector is used and the multiple feeds are pointed directly toward the desired coverage region.
  • the amplitude and phase weightings on the feed elements can be optimised to prodoce continuous area coverage.
  • These antenna concepts are frequently used in spacecraft applications, and extremely large clusters in excess of 100 elements are often required.
  • These large feed arrays also require complex power splitting arrangements known as beam forming networks (BFN's) which require precision manufacture and close thermal control.
  • BFN's beam forming networks
  • the multibeam antenna generally uses the single offset reflector configuration to achieve high efficiency, but this again suffers from the inherent crosspolarisation generated by this geometry for linearly polarised applications.
  • This shortcoming can be overcome by a new development in reflector technology, the gridded reflector.
  • This is a reflector with a polarisation dependent reflective surface on the front and rear faces of a cellular sandwich construction.
  • the reflective surface is comprised of finely spaced conductive lines printed on the outer skins of the reflector, which are aligned to reflect the desired linear polarisation only, and therefore, the undesired polarisation does not contribute to the antenna coverage area.
  • This technology is still in an early development phase and is a complex and expensive solution due to the manufacturing processes used, and the tight control necessary on the reflector thickness.
  • the shaped reflector is generally used for a single coverage with a regular elliptical or moderately irregular coverage.
  • This antenna system has significant advantages in that only one feed element is used and the shaping of the coverage area is generated by small deviations in the reflector surface profile from an originally parabolic form.
  • the technique can be used with either single, dual or multiple reflector antenna systems.
  • the single reflector approach is limited, however, in the extent to which the coverage area can be shaped and also in that, for single offset reflector systems, the cross polarisation levels obtained in transmission produced by the antenna geometry are degraded from that of the front fed reflector systems for linear polarisation applications.
  • the dual reflector antenna geometry may chosen to produce low cross polarisation in a linearly polarised system by choosing the feed angle in the offset plane to satisfy the Mizugutch condition ('Offset Dual Reflector Antenna" by Mizugutch Y, Akagawa U and Yokoi U; Proc. APS Symposium Amhurst Mass. 1976). 7his angular constraint guarantees low cross polarisation over a wide bandwidth.
  • a method ofproducing an antenna system which is capable of passing radiation either to or from a shaped coverage area, or both simultaneously, the system including a three dimensional reflector surface positioned to transmit radiation to or receive radiation from said area, the method including:-
  • the antenna system naturally includes radiation emitting or accepting means positioned for directing radiation onto or receiving radiation from the reflector surface.
  • the radiation emitting or accepting means can be, for example, a feed or receiving horn arrangement either use alone or in conjunction with a further reflector surface.
  • the further reflector surface may or may not require development in a similar and simultaneous manner to that of the first-mentioned reflector surface.
  • a means of producing an antenna system which is capable of passing radiation either to or from (or simultaneously to and from) a shaped coverage region simultaneously in two orthogonal polarisations of the same frequency.
  • the said orthogonal polaristions may be either linear or circular in nature.
  • the system includes two or more three dimensional reflector surfaces one or more of which is shaped according to the procedure defined in the first aspect of this invention.
  • the antenna system naturally includes radiation emitting or accepting means for directing radiation onto or receiving radiation from the main reflector surface.
  • the said radiation emitting or accepting means can be, for example, a feed or receiving horn arrangement with suitable means for combining or separating the two orthogonally polarised radiation signals, used in conjunction with one or more further reflector surfaces.
  • the two or more reflector surfaces are chosen initially to be undistorted conics arranged relative to the feed or receiving horn to satisfy approximately or exactly the Mizugutch angular contraint I11 for low linear cross polarisation.
  • the surface of the main reflector, and subsequent reflectors is so desired, are then distorted according to the procedure of the first aspect of this invention to optimise the far field radiation.
  • the subreflector may then need to be adjusted in angle to improve the crosspolar performance.
  • a procedure is provided for generalisation of the previously stated aspects to provide multiple simultaneous shaped coverage regions from the a single antenna.
  • the single feed or receiving horn is replaced by an array of such radiating devices.
  • One or more feeds or receiving horns is required for each beam and the radiation pattern produced by the shaped reflector must be chosen as a compromise between the differing requirements of the different beams.
  • This multibeam shaped reflector antenna may be designed, for example, so that each beam is flat-topped and approximately hexagonal in shape. The geometry may be chosen so that neighbouring feeds produce neighbouring beams. By choosing beams with low sidelobes, signals, with identical frequencies may be used in non-neighbouring beams without undue interference one to the other.
  • switches or variable power divide network mens the beams of the antenna may be reconfigured in the usual way for a multifeed antenna.
  • the advantage of the shaped reflector mulifeed antenna described in aspect three of this invention is the potential reduction in the number of feeds required and thus a reduction in losses and complexity in the associated power divide network.
  • the method of shaping a single main reflector to obtain the required coverage will be described. Naturally, the method may also be applied to a sub-reflector or both reflectors of a dual reflector system.
  • each of these regions are required to have a given directivity specification ie the ratio of power transmitted in a given direction to the total power transmitted by the antenna system - these values being X d B for region 1, (X-3) d B for region 2, and (X-6)dB for region 3 (where X is greater than 30.3dB after losses).
  • the antenna system is then defined by the basic unshaped parameters, for example, for a basic unshaped paraboloidal reflector, these are:-
  • the feed born offset at an angle of 30.55° directs two orthogonally polarised radiation beams at a frequency of 14.5GHz onto the reflector which has a basic far-field pattern as shown in Figure 2, each area receiving a different strength output of the beams.
  • the method optimises the shape of the reflector surface so that the minimum directivity obtained from a series of m far-field points is maximised - the m points being shown in Figure 3 as a set of black dots indicating the points to which the beam is to be directed.
  • These points are user-defined and are initially specified in terms of longitude and latitude, and are then converted to coordinates in the antenna system.
  • the optimisation of the shape of the reflector surface is carried out on a basic function Z(x,y) (obtained from the shape of the basic reflector) plus an arbitrary function expanded as a two-dimensional Fourier series, that is, where ie the Fourier series describes a function with period 2h in the x-direction and period 2k in the y-direction with origin at (x c ,y c ).
  • Variables h, k, x c . y c are defined by the user and are related to the antenna system vhich is being used.
  • the variables etc. are optimisation variables.
  • the other parameters were set to:-
  • the gross features of the coverage area are obtained by distorting the basic paraboloidal reflector using quadratic distortions in x and y, the distortions being of the form where x 0 is the x-coordinate of the aperture centre and
  • the first two terms generate a roughly elliptical beam shape, and the third term points the beam slightly north.
  • the resulting far-field pattern for the distorted reflector is shown in Figure 4.
  • the optimisation method involves a series of iterative steps in which the directivity is calculated at each of the m far-field points.
  • the reflector distortions are defined as a two-dimensional Fourier series, the coefficients of the series being the optimisation variables.
  • the directivity for each point is calculated for various sets of coefficients, each calculation or iteration involving only one set of coefficients and utilises physical optics.
  • the method gradually produces an optimum set of coefficients, ie the 49 Fourier coefficients in the optimised state with the minimum directivity value maximised.
  • the resulting far-field plot is shown in Figure 5, with Figure 6 showing a contour plot of the minimum directivity inside each of the regions 1, 2 and 3.
  • the visible differences are due to the quadratic distortions - the Fourier distortions being too small to be discerned. This is because the quadratic distortions are of the order of 5 to 6cm, the Fourier distortions, shown in Figure 9 in three-dimensional form, being of the order of 3mn.
  • the optimisation methods disclosed may be carried out by a suitably programmed computer and the resulting optimised reflector surface shapes, given in the form of mathematical function and/or a table of z-direction displacements for a series of x, y coordinate positions over the reflector surface can be converted by suitable software, of which examples are known, into a control program for computer controlled machine tool.
  • This tool then cuts the required reflector surface shape from a workpiece or, more likely, cuts that shape in a metal or graphite block which is then used as a mould for forming the reflector using known composite technology.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Remote Sensing (AREA)
  • Aerials With Secondary Devices (AREA)
EP86307829A 1985-10-10 1986-10-09 Antennensystem Withdrawn EP0219321A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8525016 1985-10-10
GB8525016 1985-10-10

Publications (1)

Publication Number Publication Date
EP0219321A1 true EP0219321A1 (de) 1987-04-22

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Family Applications (1)

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EP86307829A Withdrawn EP0219321A1 (de) 1985-10-10 1986-10-09 Antennensystem

Country Status (1)

Country Link
EP (1) EP0219321A1 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0346105A2 (de) * 1988-06-09 1989-12-13 British Aerospace Public Limited Company Antennensystem für ein Raumfahrzeug
EP0353846A2 (de) * 1988-06-09 1990-02-07 British Aerospace Public Limited Company Verfahren zur Herstellung eines Antennensystems mit Haupt- und Hilfsreflektorflächen
GB2231203A (en) * 1989-03-14 1990-11-07 Kokusai Denshin Denwa Co Ltd An antenna system for shaped beam
US5258767A (en) * 1989-03-14 1993-11-02 Kokusai Denshin Denwa Co., Ltd. Antenna system for shaped beam
EP1085598A2 (de) * 1999-09-20 2001-03-21 EADS Deutschland Gmbh Reflektor mit geformter Oberfläche und räumlich getrennten Foki zur Ausleuchtung identischer Gebiete, Antennensystem und Verfahren zur Oberflächenermittlung
CN107210536A (zh) * 2014-12-05 2017-09-26 Nsl通讯有限公司 用于调谐远程天线的系统、设备和方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2850492A1 (de) * 1977-11-25 1979-05-31 Cselt Centro Studi Lab Telecom Antennenreflektor mit parabolisch- elliptischer reflektorflaeche
US4236161A (en) * 1978-09-18 1980-11-25 Bell Telephone Laboratories, Incorporated Array feed for offset satellite antenna
WO1986003344A1 (en) * 1984-11-19 1986-06-05 Hughes Aircraft Company High gain-area-product antenna design

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2850492A1 (de) * 1977-11-25 1979-05-31 Cselt Centro Studi Lab Telecom Antennenreflektor mit parabolisch- elliptischer reflektorflaeche
US4236161A (en) * 1978-09-18 1980-11-25 Bell Telephone Laboratories, Incorporated Array feed for offset satellite antenna
WO1986003344A1 (en) * 1984-11-19 1986-06-05 Hughes Aircraft Company High gain-area-product antenna design

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION vol. AP-32, no. 9, September 1984, pages 963-968, New York, US; C.A. KLEIN "Design of shaped-beam antennas through minimax gain optimization" *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0346105A2 (de) * 1988-06-09 1989-12-13 British Aerospace Public Limited Company Antennensystem für ein Raumfahrzeug
EP0353846A2 (de) * 1988-06-09 1990-02-07 British Aerospace Public Limited Company Verfahren zur Herstellung eines Antennensystems mit Haupt- und Hilfsreflektorflächen
EP0353846A3 (de) * 1988-06-09 1991-07-03 British Aerospace Public Limited Company Verfahren zur Herstellung eines Antennensystems mit Haupt- und Hilfsreflektorflächen
EP0346105A3 (de) * 1988-06-09 1991-07-03 British Aerospace Public Limited Company Antennensystem für ein Raumfahrzeug
US5160937A (en) * 1988-06-09 1992-11-03 British Aerospace Public Limited Company Method of producing a dual reflector antenna system
GB2231203A (en) * 1989-03-14 1990-11-07 Kokusai Denshin Denwa Co Ltd An antenna system for shaped beam
GB2231203B (en) * 1989-03-14 1993-09-08 Kokusai Denshin Denwa Co Ltd An antenna system for shaped beam
US5258767A (en) * 1989-03-14 1993-11-02 Kokusai Denshin Denwa Co., Ltd. Antenna system for shaped beam
EP1085598A2 (de) * 1999-09-20 2001-03-21 EADS Deutschland Gmbh Reflektor mit geformter Oberfläche und räumlich getrennten Foki zur Ausleuchtung identischer Gebiete, Antennensystem und Verfahren zur Oberflächenermittlung
JP2001127538A (ja) * 1999-09-20 2001-05-11 Daimlerchrysler Ag アンテナ用の反射鏡、前記反射鏡を用いたアンテナシステム、及び前記反射鏡の表面形状の決定方法
EP1085598A3 (de) * 1999-09-20 2002-07-31 EADS Deutschland Gmbh Reflektor mit geformter Oberfläche und räumlich getrennten Foki zur Ausleuchtung identischer Gebiete, Antennensystem und Verfahren zur Oberflächenermittlung
EP1321999A1 (de) * 1999-09-20 2003-06-25 Astrium GmbH Reflektor mit geformter Oberfläche und räumlich getrennten Foki zur Ausleuchtung identischer Gebiete und Verfahren zur Oberflächenermittlung
CN107210536A (zh) * 2014-12-05 2017-09-26 Nsl通讯有限公司 用于调谐远程天线的系统、设备和方法
EP3227964A4 (de) * 2014-12-05 2018-08-01 NSL Comm Ltd System und verfahren zur einstellung einer fernantenne
US10916858B2 (en) 2014-12-05 2021-02-09 Nsl Comm Ltd System, device and method for tuning a remote antenna
CN107210536B (zh) * 2014-12-05 2021-07-30 Nsl通讯有限公司 远程可调谐的天线组件及其副反射器和相关方法

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Inventor name: WILCOCKSON, PHILIP C.BRITISH AEROSPACE PUBLIC

Inventor name: FAIRLIE, ROBERT H.BRITISH AEROSPACE PUBLIC

Inventor name: ROBSON, DAVID, DR.BRITISH AEROSPACE PUBLIC