GREGORIAN ANTENNA WITH RING FOCUS

• US 3,710,341 A
• Filed: 03/17/1971
• Issued: 01/09/1973
• Est. Priority Date: 03/17/1971
• Status: Expired due to Term

• Current Assignee: Attilio F. Sciambi Jr
• Original Assignee: Attilio F. Sciambi Jr
• Inventors: Sciambi, Attilio F. Jr.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/125,265
• Time in Patent Office: 664 Days
• Field of Search: 343/781,837,840,779,782
• US Class Current: 343/779
• CPC Class Codes: H01Q 5/45 using two or more feeds in association with a common reflecting, diffracting or refracting device

Abstract

A Gregorian antenna system has the usual main reflector, subreflector, a first feed for illuminating the main reflector from the virtual focus via the subreflector, and a second feed for directly illuminating the main reflector from a prime focus. The second feed is shaped, and is positioned relative to the subreflector, to create a ring focus for energy reflected from the subreflector to the main reflector, and the main reflector is shaped to have the ring focus as its prime focus.

Claims

1. A Gregorian antenna system, comprising a main reflector, a subreflector, a first feed for illuminating said main reflector via said subreflector, and a second feed for directly illuminating said main reflector, said second feed being shaped, and positioned relative to said subreflector, to produce a ring focus for energy reflected from said subreflector toward said main reflector, said main reflector being shaped to have said ring focus as its prime focus.

2. The antenna system according to claim 1, wherein said second feed has a cylindrical external surface with an axis coincident with the axis of said subreflector.

3. The antenna system according to claim 2, wherein said ring focus has a center lying on said axis and a radius Delta , and said main reflector is a surface of revolution formed by rotation of a curve having a locus of points (y- Delta )2 4 fx about its axis of symmetry, where f is the focal length of the curve, and x and y are Cartesian coordinates.

4. A Gregorian antenna system, comprising a main reflector, a subreflector positioned relative to said main reflector to share a common prime focus therewith, first feed means for illuminating said subreflector, and second feed means for illuminating said main reflector and for creating a ring focus for transfer of energy between said subreflector and said main reflector, said main reflector having a reflecting surface shape with a prime focus coincident with said ring focus.

5. The antenna system according to claim 4, wherein said second feed means includes a feed and a symmetrical reflective external surface for said feed.

6. The antenna system according to claim 5, wherein said symmetrical reflective external surface is cylindrical in shape and shares a common axis with said subreflector.

7. The antenna system according to claim 5, wherein said ring focus has a radius Delta about the axis of said antenna system, and said main reflector is a figure of revolution defined by rotating about its axis of symmetry a curve having a locus of points according to (y- Delta )2 4 fx where f is the focal length of the curve, and x and y are Cartesian coordinates.

8. A Gregorian antenna system, comprising a main reflector, a subreflector for reflecting energy toward and receiving energy from said main reflector, first feed means for illuminating said main reflector, and second feed means for illuminating said subreflector, said first feed means being positioned relative to said subreflector and said main reflector to intercept substantially all of the energy emanating from one of said subrefLector and said main reflector, and having a surface covering and shape to reflect the incident energy substantially completely onto the surface of the other of said subreflector and said main reflector.

9. The antenna system according to claim 8, wherein said main reflector is shaped to possess a prime focus conforming to the focus associated with energy reflected from said first feed means.