US3641577A - Scanning antenna having a spherical main reflector with moveable subreflector - Google Patents

Scanning antenna having a spherical main reflector with moveable subreflector Download PDF

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Publication number
US3641577A
US3641577A US806458A US3641577DA US3641577A US 3641577 A US3641577 A US 3641577A US 806458 A US806458 A US 806458A US 3641577D A US3641577D A US 3641577DA US 3641577 A US3641577 A US 3641577A
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Prior art keywords
reflector
transducer
waves
antenna
center
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Expired - Lifetime
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US806458A
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English (en)
Inventor
Yves Tocquec
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Alcatel Lucent SAS
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Compagnie Generale dElectricite SA
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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
    • H01Q19/191—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 wherein the primary active element uses one or more deflecting surfaces, e.g. beam waveguide feeds

Definitions

  • the present invention relates to radio antennas with an orientable or adjustable major lobe and is concerned more particularly with very large-size antennas comprising a large reflector whose configuration is essentially that of a spherical cap.
  • Such a reflector may have a diameter in the order of about 100 meters, for example. It must be nondeformable, by the action of the wind particularly, and therefore must be relatively heavy; and, it is expensive to build such antennas in a manner such that they can be adapted to be oriented or adjusted.
  • Antennas ofxthis type are designed, however, especially for establishing communications with artificial satellites which are placed in orbit around the earth for purposes of telecommunication. Now, since such satellites canscarcely be rendered completely.
  • the emission lobe'of maximuni fpower, or the reception lobe of maximum sensitivity, ofthe antenna musttherefore be orientable or adjustable, and the angular variation possible must be in the order of at least several degrees of variation.
  • the. large reflector With respect to the ground and, in the case where the antenna is utilized for emission, to irradiate it by means of a small reflector,disposed in proximity to the focal point thereof.
  • the source of emission can be considered as punctiform, which is generally the case, the shape of the small reflector is chosen in such a manner as to couple the point of emission with the focal point of the large reflector in such a way that the waves received by this large reflector seem -to diverge from this point, so that as a result the beam emitted by the large reflector is composedof essentially, parallel waves.
  • an orientable large reflector it is possible toobtain from such a punctiform source a rigorous parallelism for the emitted beam (if the diffraction phenomena are disregarded).
  • the large reflector with the shape of a paraboloid of revolution and the-small reflector with the shape of an ellipsoid or hyperboloid of revolution, one of the two focuses of the small reflector being positioned on the emission source and the other one of thesetwo focuses coinciding with the focus of the large reflector.
  • This favorable situation cannot be maintained when the direction of the emitted beam must be made to vary with respect to the axis of the large reflector.
  • the latter must then be considered as no longer consisting of one focus but a focal surface each of the points of which plays the role of focus for a specific orientation of the'emitted beam.
  • the small reflector is then utilized for focusing the radiations on the suitable point of the focal surface.
  • the position of the small reflector must therefore vary as a function of the point in question. Under these conditions, the stigmatism of the optical system being constituted in this manner, that is to say, in practice, the parallelism of the emitted beam, can only be approximate.
  • the present invention renders it possible to obviate the drawbacks and difficulties outlined above.
  • the antenna having an orientable or adjustable lobe as proposed by the present invention comprises a large stationary reflector having theshape of a spherical cap and an intermediate optical system through which pass the radioelectric waves between this large reflector and a source.
  • This source consists of an emitter of radioelectric waves, if the antenna is used for emission; it consists instead of .a receiver, if theantenna is used for reception.
  • the intermediate antenna system is movable with respect to the large reflector in such amanner that the orientation or adjustment of the lobe is determined b the position of this antenna system. 1
  • the antenna according to the present invention is characterized by the fact. that'the intermediate antenna system is movable by rotation around the center of curvature of the large reflector and that this intermediate antenna system is adapted to couple .the center of curvature with the focal point I of this large reflector, means being additionally provided to ensure that the waves which are emitted by the source or to which this source is sensitive have spherical wave surfaces centered on this center of curvature.
  • FIG. 1 is a schematic diagram of an antenna arrangement in accordance with the present invention
  • FIG. 2 is a partially schematic structural view of an antenna according to FIG. 1;
  • FIG. 3 is a detail perspective view of a small reflector and adjustable support therefor;
  • FIGS. 4 and 5 are schematic diagrams of alternative embodiments of the invention, respectively.
  • FIGS. 6 and 7 are schematic diagrams illustrating beam patterns in connection with an antenna in accordance with the present invention.
  • FIGS. 1 to 3 illustrate a first embodiment of the present invention including, in a manner known per se, a large reflector 1 having the shape of a spherical cap whose center of curvature is positioned at point 0.
  • a horn 2 is connected to this reflector l by means of a surface 3, the horn being directed at the surface 3 and opening out at the approximate center of the reflector 1.
  • this surface 3 is geometrically part of an ellipsoid, one of the focuses of which coincides with the center of the large reflector l and whose other focus F is positioned on the geometrical axis z, z of the horn 2 preferably at the vertex of the latter.
  • a small reflector 4 is preferably disposed essentially halfway between the surface 3 and the point 0, the antenna being then of the Gregorian type, in the case of FIG. 1.
  • FIG. 2 illustrates more completely the'structural arrangement of the antenna according to FIG. 1. Shown in this figure is the small reflector 4 supported by a swivel or ball-andsocket joint 5 connected by means of arms 6, 6' to a caisson 7 which in turn is carried or supported by leg supports 8, 8' secured to the principal reflector l.
  • the front of this caisson 7, with respect to the reflectors, is inclined about 45 on the axis of the reflector l, and the apparent surface of this inclined member is above that of the small reflector 4 so that the parasitic portion of the beam emitted by the elliptical reflector 3 towards the reflector 4 that is to say, the portion passing to the side of the latter-is returned or reflected in a direction which is as little disturbing as possible, at 90 from the direction of the principal lobe.
  • a source of waves 2' is connected to the vertex of the horn 2 and the elliptical wall '3 of the horn then radiates a wave which converges toward the center of curvature 0 of the large reflector.
  • the phase surfaces" of this wave consequently are spheres which have as their center this center of curvature 0. Under these conditions, a rotation of the small reflector 4 by a certain angle around this center causes a rotation of the wave emitted by the antenna which has the same angular value and the same direction.
  • FIG. 3 shows a device which may be used for supporting the auxiliary reflector while permitting displacement thereof in two orthogonal directions.
  • two plates 12 and 13 cooperate by means of cylindrical surfaces in such a manner as to allow for a displacement of the reflector 4 in the direction X
  • the plate 13 and the base 14 similarly cooperate by means of cylindrical surfaces oriented in such a manner as to allow for a displacement in the direction Y perpendicular to X.
  • the reflector 4 may thus be displaced along a spherical surface whose center coincides with the center of curvature 0 of the large reflector.
  • FIGS. 4 and 5 illustrate schematically other embodiments of antennas as proposed by the present invention.
  • the horn 2 is disposed along the axis of the large reflector l on the convex side of the latter, and an electromagnetic lens 15 is positioned at the opening of this horn in the reflector so as to obtain a wave which is centered at 0, the center of curvature of the large reflector 1.
  • a horn 16 or other conventional primary wave source for example, a Yagi antenna, is disposed at the center of the large reflector l and oriented toward the latter, and either a dielectric or a metallic lens 17 is located approximately halfway between this horn l6 and the principal reflector 1.
  • the waves are likewise centered at 0, the center of curvature of the large reflector, but they are divergent at the emission.
  • the device according to FIG. 3 may be used for the displacement of the lens 17, the latter being supported by an arm so as to prevent the plate from being placed in the field thereof. Any displacement of the lens around the center of curvature 0 of the large reflector produces a rotation of the wave beam emitted by the antenna having the same angular value and the same direction. It is then of advantage to cause the horn 16 to pivot around the point 0 so that the beam which it emits remains centered on the lens 17.
  • FIG. I the edges of the beam of waves have not been defined.
  • FIGS. 6 and 7, being analogous to FIG. 1, represent the position of these edges when the beam emitted by the antenna must be parallel to the axis of the large reflector, and when this beam mustbe removed or distant from this axis, respectively.
  • reference numeral 20 represents an emission horn pivoting around the point F. This horn radiates over a variable portion of the elliptical mirror 3, according to the orientation thereof. This orientation is controlled by mechanical adjusting means 24 for regulating the position of the small reflector 4 in such a manner that the beam being reflected by the elliptical mirror 3 toward the small reflector 4 is centered on the latter at all times.
  • the aperture of the beam emitted by the horn 20 is such that the width of the beam irradiating the small reflector 4 is essentially equal to the width of this reflector.
  • the latter focuses the beam in a point on the focal surface 22 of the large reflector 1.
  • This focal surface is a spherical portion having its center at the center 0 and having half the radius of that of the sphere of which the large reflector l constitutes a cap portion.
  • the beam then diverges from this point on the focal surface and reaches the large reflector l where it gives rise to a parallel emission of the beam.
  • the direction of this emission is parallel to the straight line joining the center of curvature 0 with the center of the small reflector 4.
  • An antenna having an orientable major lobe comprising a first relatively large reflector having the shape of a spherical cap,
  • a transducer for emitting or receiving electromagnetic waves
  • said intermediate optical system including first means movable at least in part and displaced with respect to the center of curvature of said large reflect or by rotation around the center of curvature thereof for coupling said center of curvature to a focal point of said large reflector and second means for ensuring that the waves associated with said transducer have spherical wave surfaces centered on said center of curvature of said large reflector, wherein said first means includes a second relatively small reflector positioned in proximity to the focus of said large reflector, said transducer being positioned on the opposite side of said large reflector from said small reflector with said waves being transmitted to and from said small reflector through an opening in said large reflector.
  • said second means includes a third elliptical reflector connected to said large reflector to provide a surface contiguous thereto and having the shape of a portion of an elongated ellipsoid of revolution, the first focus of said ellipsoid being located at the center of curvature of said large reflector and the second focus thereof being located at the position of said transducer.
  • said second means includes an electromagnetic lens positioned in said opening in said large reflector and a horn coupling said transducer to said opening along a line coextensive with the axis of said large reflector.
  • said intermediate optical system further includes adjusting means for coordinately adjusting the relative positions of said transducer and said small reflector so that waves associated with said transducer are reflected at all times only over the entire useful surface of said small reflector.
  • An antenna having an orientable major lobe comprising:
  • a first relatively large fixed reflector having the shape of a spherical cap
  • a transducer for emitting or receiving electromagnetic spherical waves
  • said small reflector being positioned in proximity to the focal surface of said large reflector and shaped for correcting spherical aberrations of said large reflector in such a way that plane waves reflected by the same small reflector after having been reflected by said large reflector are so converted into spherical waves;
  • said small reflector including means movable at least in part with respect to said large reflector for providing movement of said small reflector over a spherical surface centered at the center of curvature of said large reflector in such a way that this movement is a rotation around said center of curvature;
  • said small reflector is shaped for said plane waves to be converted into spherical waves centered at said center of curvature
  • transducer being positioned on the convex side of said large reflector for emitting or receiving spherical waves centered at a fixed point;
  • fixed transmitting means being positioned in view of an opening through said large reflector for transmitting said waves between said small reflector and transducer through said opening in such a way that spherical waves centered at said center of curvature are converted into spherical waves centered at said fixed point.

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US806458A 1968-03-12 1969-03-12 Scanning antenna having a spherical main reflector with moveable subreflector Expired - Lifetime US3641577A (en)

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FR143418 1968-03-12

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3939480A (en) * 1974-09-17 1976-02-17 The United States Of America As Represented By The Secretary Of The Navy Level and cross-level stabilization technique for search radar antennas
US3968497A (en) * 1974-03-19 1976-07-06 Thomas-Csf Antenna with a periscope arrangement
US4062018A (en) * 1973-12-21 1977-12-06 Kokusai Denshin Denwa Kabushiki Kaisha Scanning antenna with moveable beam waveguide feed and defocusing adjustment
US4195302A (en) * 1976-06-25 1980-03-25 Siemens Aktiengesellschaft Double reflector antenna with feed horn protection
US4274098A (en) * 1980-03-07 1981-06-16 The United States Of America As Represented By The Secretary Of The Air Force Loss-free scanning antenna
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US5247843A (en) * 1990-09-19 1993-09-28 Scientific-Atlanta, Inc. Apparatus and methods for simulating electromagnetic environments
US5459475A (en) * 1993-12-22 1995-10-17 Center For Innovative Technology Wide scanning spherical antenna
WO2006096979A1 (en) * 2005-03-18 2006-09-21 The University Of British Columbia Reflector antenna

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5028148B1 (da) * 1969-11-28 1975-09-12

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2609505A (en) * 1944-06-17 1952-09-02 Pippard Alfred Brian Aerial system
US2677056A (en) * 1950-07-28 1954-04-27 Elliott Brothers London Ltd Aerial system
US2975419A (en) * 1959-10-13 1961-03-14 Newell H Brown Microwave antenna reflector system for scanning by displacement of focal image
US2976533A (en) * 1954-11-12 1961-03-21 Zenith Radio Corp Radio astronomy antenna having spherical reflector formed integral with earth's surface
US2986734A (en) * 1958-07-02 1961-05-30 Mini Of Supply Electromagnetic wave lens and mirror systems
US3195137A (en) * 1960-12-27 1965-07-13 Bell Telephone Labor Inc Cassegrainian antenna with aperture blocking correction
US3241147A (en) * 1963-12-16 1966-03-15 Bell Telephone Labor Inc Antenna utilizing intermediate cuspate reflector to couple energy from feed to main reflector
US3332083A (en) * 1963-06-14 1967-07-18 Csf Cassegrain antenna with offset feed
US3383692A (en) * 1965-01-07 1968-05-14 Whittaker Corp Main dish with adjustable subreflector
US3534373A (en) * 1968-03-22 1970-10-13 North American Rockwell Spherical reflector antenna with waveguide line feed

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2609505A (en) * 1944-06-17 1952-09-02 Pippard Alfred Brian Aerial system
US2677056A (en) * 1950-07-28 1954-04-27 Elliott Brothers London Ltd Aerial system
US2976533A (en) * 1954-11-12 1961-03-21 Zenith Radio Corp Radio astronomy antenna having spherical reflector formed integral with earth's surface
US2986734A (en) * 1958-07-02 1961-05-30 Mini Of Supply Electromagnetic wave lens and mirror systems
US2975419A (en) * 1959-10-13 1961-03-14 Newell H Brown Microwave antenna reflector system for scanning by displacement of focal image
US3195137A (en) * 1960-12-27 1965-07-13 Bell Telephone Labor Inc Cassegrainian antenna with aperture blocking correction
US3332083A (en) * 1963-06-14 1967-07-18 Csf Cassegrain antenna with offset feed
US3241147A (en) * 1963-12-16 1966-03-15 Bell Telephone Labor Inc Antenna utilizing intermediate cuspate reflector to couple energy from feed to main reflector
US3383692A (en) * 1965-01-07 1968-05-14 Whittaker Corp Main dish with adjustable subreflector
US3534373A (en) * 1968-03-22 1970-10-13 North American Rockwell Spherical reflector antenna with waveguide line feed

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4062018A (en) * 1973-12-21 1977-12-06 Kokusai Denshin Denwa Kabushiki Kaisha Scanning antenna with moveable beam waveguide feed and defocusing adjustment
US3968497A (en) * 1974-03-19 1976-07-06 Thomas-Csf Antenna with a periscope arrangement
US3939480A (en) * 1974-09-17 1976-02-17 The United States Of America As Represented By The Secretary Of The Navy Level and cross-level stabilization technique for search radar antennas
US4195302A (en) * 1976-06-25 1980-03-25 Siemens Aktiengesellschaft Double reflector antenna with feed horn protection
US4274098A (en) * 1980-03-07 1981-06-16 The United States Of America As Represented By The Secretary Of The Air Force Loss-free scanning antenna
US4535338A (en) * 1982-05-10 1985-08-13 At&T Bell Laboratories Multibeam antenna arrangement
US5247843A (en) * 1990-09-19 1993-09-28 Scientific-Atlanta, Inc. Apparatus and methods for simulating electromagnetic environments
US5459475A (en) * 1993-12-22 1995-10-17 Center For Innovative Technology Wide scanning spherical antenna
WO2006096979A1 (en) * 2005-03-18 2006-09-21 The University Of British Columbia Reflector antenna
US20080204342A1 (en) * 2005-03-18 2008-08-28 The University Of British Columbia Reflector Antenna
US7733282B2 (en) 2005-03-18 2010-06-08 Mostafa M. Kharadly Reflector antenna

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Publication number Publication date
DE1912565A1 (de) 1970-10-01
FR1569747A (da) 1969-06-06

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