TORUS-TYPE ANTENNA HAVING A CONICAL SCAN CAPABILITY

• US 3,852,763 A
• Filed: 12/04/1972
• Issued: 12/03/1974
• Est. Priority Date: 06/08/1970
• Status: Expired due to Term

• Current Assignee: Geoffrey Hyde, Randall William Jr. Kreutel
• Original Assignee: Geoffrey Hyde, Randall William Jr. Kreutel
• Inventors: Kreutel, Randall William Jr., Hyde, Geoffrey
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/311,984
• Time in Patent Office: 729 Days
• Field of Search: 343/781,840,912,914,DIG.2,761,1ST
• US Class Current: 343/761
• CPC Class Codes: H01Q 19/12 wherein the surfaces are concave H01Q19/18 takes precedence
• CPC Class Codes: H01Q 3/16 for varying relative position of primary active element and a reflecting device
• CPC Class Codes: H01Q 3/18 wherein the primary active element is movable and the reflecting device is fixed
• CPC Class Codes: Y10S 343/02 Satellite-mounted antenna

Abstract

A reflector type antenna which is formed by rotating a generating curve, having an axis of beam direction, about a fixed axis such that the axis of beam direction defines a beam scanning surface corresponding to the surface of a cone. Scanning is obtained by rotating a feed on the arc of a circle centered on the fixed axis so that, due to symmetry, radiation patterns on the beam scanning surface are identical for all feed positions. The beam scanning surface so described permits an approximation to the conical surface defined by a group of lines drawn from an earth station site to points on the geostationary arc.

Claims

1. A torus-type reflector antenna wherein the reflector surface is described by a substantially smooth generating curve rotated about an axis of rotation which is coplanar with the generating curve and disposed on the concave side of said curve and wherein the reflector surface, when illuminated with electromagnetic energy from a feed means lying at a feed point in the plane defined by said generating curve and said axis of rotation forms a substantially focused beam along an axis of beam direction defined by a line lying in said plane and drawn between the reflecting surface and a remote target point, the improvement comprising:

a. said generating curve substantially comprising a conic section, except a conic section which is the arc of a circle;

b. said reflector surface being formed by rotating said generating curve about an axis of rotation which intersects the axis of beam direction at an angle Alpha which is not equal to 90*;

c. said feed means being capable of illuminating said reflector surface from one or more points on an arc, defined by the rotation of said feed point about the axis of rotation, whereby the axes of beam direction of beams formed and directed by the reflecting surface intersect the axis of rotation at said angle Alpha and define the surface of a cone having a half angle of 180*- Alpha for 90*<

Alpha <

180*.

2. A torus-type reflector antenna wherein the reflector surface is described by a substantially smooth generating curve rotated about an axis of rotation which is coplanar with the generating curve and disposed on the concave side of said curve and wherein the reflector surface, when iLluminated with electromagnetic energy from a feed means lying at a feed point in the plane defined by said generating curve and said axis of rotation forms a substantially focused beam along an axis of beam direction defined by a line lying in said plane and drawn between the reflecting surface and a remote target point, the improvement comprising:

a. said generating curve substantially comprising a conic section, except a conic section which is the arc of a circle;

b. said reflector surface being formed by rotating said generating curve about an axis of rotation which intersects the axis of beam direction at an angle Alpha which is not equal to 90*;

c. said feed means being capable of illuminating said reflector surface from one or more points on an arc, defined by the rotation of said feed point about the axis of rotation, whereby the axes of beam direction of beams formed and directed by the reflecting surface intersect the axis of rotation at said angle Alpha and define the surface of a cone having a half angle of Alpha for Alpha <

90*.

3. The invention recited in claim 1 wherein the generating curve is a conic section having a unique section axis which is parallel to the axis of beam direction and lies in the plane defined by the generating curve and the axis of rotation.

4. The invention recited in claim 3 wherein the feed means comprises a plurality of selectively energizable electromagnetic feeds disposed along an arc centered about the axis of rotation and lying in a plane of the circular cross section of said reflecting surface.

5. The invention as recited in claim 2 wherein the reflecting surface defines a 360* toroid and said feed means is deployed to provide a conical scan over 360*.

6. A terrestrial reflector antenna for scanning along a target arc comprising:

a. a toroidal reflector surface, described by the rotation of a substantially smooth generating curve, which substantially comprises a conic section, except a conic section which is the arc of a circle, and has an axis of rotation which intersects the axis of beam direction at an angle Alpha which is greater than 90* and less than 180*; and

b. a plurality of sources of electromagnetic energy for illuminating said surface, each source being located on an arc at an identical distance from said surface to form and direct beams along said axes of direction whereby the surface described by the axes of beams from said antenna to points on the target arc approximates the surface of a right circular cone having a half angle of 180*- Alpha .

7. A satellite communication system, comprising a plurality of satellites located in a geostationary arc, terrestrial antenna mean, said terrestrial antenna means including stationary reflector means for scanning along a target arc, which reflector means comprises a toroidal reflecting surface having an axis of rotation and a generating curve which approximates a conic section, except a conic section which is the arc of a circle, and feed means symmetrically deployable on an arc about said axis of rotation and lying in a plane perpendicular to said axis of rotation, said feed means illuminating said reflecting surface to form and direct one or more beams along axes of beam direction from said reflecting surface to said satellites, each of said axes of beam direction intersecting said axis of rotation at an angle Alpha greater than 90*, wherein said target arc approximates the geostationary arc and the locus of said axes of beam direction is the surface of a cone having a half angle of 180*- Alpha .