Corrugated horn fed offset paraboloidal reflector

• US 3,936,837 A
• Filed: 02/25/1975
• Issued: 02/03/1976
• Est. Priority Date: 02/25/1975
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Coleman, H. Paris, Brown, Russell M., Wright, Billy D.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/552,907
• Time in Patent Office: 343 Days
• Field of Search: 343/781, 343/837, 343/840, 343/786
• US Class Current: 343/781.00R
• CPC Class Codes: H01Q 13/0208 Corrugated horns waveguide mouth antenna with corrugated flange H01Q13/065; manufacturing details H01Q13/0283
• CPC Class Codes: H01Q 17/001 for modifying the directional characteristic of an aerial
• CPC Class Codes: H01Q 19/132 Horn reflector antennas; Off-set feeding

Abstract

A high frequency antenna achieves low signal-levels in far-out sidelobe andacklobe antenna pattern regions through utilization of a corrugated feed-horn acting as a non-axial source for a cooperating parabolic reflector.

Claims

1. A high frequency antenna system for radiating and receiving electromagnetic energy comprising:

a feed-horn having corrugations disposed on the interior conducting surface thereof;

parabolic reflective means disposed opposite the open end of said feed-horn for reflecting spherical wave-front energy radiated from said corrugated feed-horn and for converting the energy into plane-wave-front energy, and wherein said feed-horn is disposed so that none of the plane-wave-front energy is intercepted by said feed-horn;

whereby said corrugations cause low edge illumination of energy from said feed-horn incident on said parabolic reflective means;

and further wherein said feed-horn has a feed element located at the origin of an orthogonal x, y, z, axis reference system, the axis of the horn coinciding with the x axis, said feed-horn having an angle α

between the feed-horn interior surface and the x axis and a length 2 F (k² -1)^1/2 - (2FK); and

said parabolic reflective means having a parabolic surface satisfying the equation x² + y² =4F(z + F) where F is the focal length of said parabolic surface, and K is equal to tanα

;

wherein spherical energy radiating from said feedhorn is converted to plane wavefront energy traveling in the direction of the x axis.

2. The antenna system of claim 1 wherein the region between said feed-horn and said reflective means is enclosed by a conductive shroud.

3. The antenna system of claim 1 wherein a tunnel is disposed about the exit aperture of said parabolic reflective means.

4. The antenna system of claim 3 wherein said interior surface comprises absorbing material.

5. The antenna system of claim 3 wherein said tunnel has a radius to its interior surface of R = 2FK.