Compact scanning beam antenna feed arrangement

• US 4,439,773 A
• Filed: 01/11/1982
• Issued: 03/27/1984
• Est. Priority Date: 01/11/1982
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Chu, Ta-Shing
• Primary Examiner(s): Lieberman, Eli
• Assistant Examiner(s): Wimer, Michael C.
• Application Number:
  US06/338,352
• Time in Patent Office: 806 Days
• Field of Search: 343/781 P, 343/781 CA, 343/835-837, 343/778, 343/779
• US Class Current: 343/778
• CPC Class Codes: H01Q 25/001 Crossed polarisation dual antennas orthomode horns H01Q13/0258; cross-polarised rear feeds H01Q19/136; orthomode transducers H01P1/161
• CPC Class Codes: H01Q 25/007 using two or more primary active elements in the focal region of a focusing device for operation on different wavebands H01Q5/22
• CPC Class Codes: H01Q 3/2658 Phased-array fed focussing structure

Abstract

The present invention relates to a feed arrangement for use with compact scanning beam antennas which comprises a linear phased array of small feed elements (10) which form an approximate line source that radiates a wedge-shaped cylindrical beam toward a subreflector (12) which is shaped to focus the wedge-shaped cylindrical beam to a point source which then produces a spherical wavefront. The spherical wavefront can then be focused by a main reflector (14) into linear scanning beams if desired. Multiple linear phased arrays of small feed elements can be disposed parallel to each other to form a multibeam feed arrangement for producing multiple fixed or scanning spot beams.

Claims

1. An antenna feed arrangement comprising:

a plurality of feed elements (10) disposed to form a linear phased array and capable of launching or receiving a wavefront at an aperture of the linear phased array where each of the feed elements comprises a small feedhorn which in combination with the other feed elements is capable of forming an approximate line source for generating a cylindrical wedge-shaped beam at the aperture of the linear phased array;

phase shifting means (22) connected to the plurality of feed elements for selectively producing a predetermined linear phase taper along the aperture of the linear phased array; and

a reflector (12) comprising a predetermined shape for bidirectionally reflecting the cylindrical wedge-shaped beam from the linear phased array into a converging beam toward a focal plane of the antenna feed arrangement to form an approximate point source at said focal plane from which a spherical wavefront is generated.

2. An antenna feed arrangement according to claim 1 wherein the central location of an approximate point source forming a spherical wavefront is disposed at an origin of a cartesian coordinate system comprising an X, Y and Z axis, the linear phased array being disposed to orient the approximate line source parallel to the Y axis at a location where X=-C₁ and Z=-C₃, and the reflector for transformation between the approximate point source and the approximate line source is defined by

3. An antenna feed arrangement according to claim 1 or 2 wherein the aperture dimension of each feedhorn in one direction approximates two wavelengths of a frequency band signal capable of being transmitted or received by said plurality of feed elements.

4. An antenna feed arrangement according to claim 1 or 2 wherein the antenna feed arrangement comprises a second plurality of feed elements (25) disposed to form a second linear phased array parallel to said first linear phased array and capable of launching or receiving a wavefront at an aperture of the second linear phased array where each of the feed elements of the second linear phased array comprises a small feedhorn which in combination with the other feed elements of the second linear phased array is capable of forming an approximate line source for generating a cylindrical wedge-shaped wavefront at the aperture of the second linear phased array which is focused to an approximate second point source by said reflector.