Steerable directional antenna

• US 4,345,256 A
• Filed: 12/15/1980
• Issued: 08/17/1982
• Est. Priority Date: 12/15/1980
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Sperry Corporation
• Inventors: Rainwater, Lawrence L.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/216,455
• Time in Patent Office: 610 Days
• Field of Search: 343/762, 343/763, 343/765, 343/766, 343/757, 343/754, 333/261
• US Class Current: 343/754
• CPC Class Codes: H01Q 3/08 for varying two co-ordinates of the orientation

Abstract

A steerable directional antenna assembly steerable about two perpendicular axes is disclosed. It comprises a directional horn antenna rotatably mounted on a horseshoe gimbal to rotate about a first axis. A curved wave guide feed is connected at one end to the feed portion of the directional antenna. The wave guide feed is disposed such that its center of curvature is located on the first axis of rotation. The curved wave guide has a circumferential slot in its outer side, the slot communicating between the ambient atmosphere and the wave guide interior. The gimbal and directional antenna are rotatably connected to a pedestal which is enabled to rotate the gimbal and directional antenna about a second axis which is perpendicular to the first axis. The antenna assembly further comprises a coaxial feed line which passes through an opening in the pedestal and is fixed to the pedestal. The outer conductor of the coaxial feed line is stripped away from one end of the line to expose the center conductor. The center conductor terminates in an enlarged probe portion. The curved wave guide feed is disposed to receive the center conductor through the circumferential slot and the enlarged probe portion is located within the wave guide interior. A reflecting plate is also disposed within the wave guide interior at a predetermined distance from the enlarged probe portion. The reflecting plate is rotatably connected through the slot to the coaxial feed line. The reflecting plate cooperates with the wave guide and enlarged probe portion to couple RF energy between the coaxial feed line and the directional antenna. It forces RF energy to propagate between the probe and the feed portion of the directional antenna regardless of the position of the directional antenna in rotation about the first axis. When the antenna is caused to rotate about the first axis the curved wave guide feed moves relative to the center conductor and enlarged probe portion along the circumferential slot. When the directional antenna is caused to rotate about the second axis the reflecting plate rotates about the second axis to cause all the RF energy to propagate between the enlarged probe and the feed portion of the directional antenna.

Claims

1. A steerable antenna assembly comprising:

directional antenna means;

first support means attached to said directional antenna means for rotating said directional antenna means about a first axis of rotation;

second support means formed to have said first support means mounted therewith for supporting said first support means;

a coaxial feed line for transmitting RF energy, said feed line having a center conductor with a probe portion connected to one end of said center conductor, said coaxial feed line mounted to said second support means;

wave guide feed line means having a slot formed therein and electrically connected at one end to said directional antenna means, said wave guide feed line means formed to be rotatable about said first axis of rotation, said wave guide feed line means further disposed to have said center conductor extend through said slot whereby said probe is disposed within said wave guide for every angle of rotation of said directional antenna about said first axis; and

reflecting means connected to said coaxial feed line and partially disposed within said wave guide feed line means for cooperating with said probe portion and said guide feed line means to couple efficiently RF energy between said directional antenna means and said coaxial feed line.

2. The invention of claim 1 wherein said first support means is rotatably mounted to said second support means, and said second support means is formed to have said first support means rotatable therewith about a second axis of rotation substantially perpendicular to said first axis of rotation, and wherein said reflection means is rotatably coupled to said coaxial feed line whereby when said first support means and said directional antenna are rotated about said second axis said reflection means rotates therewith about said second axis.

3. The invention of claim 1 wherein said directional antenna is a dielectric lens and horn antenna combination.

4. The invention of claims 1 or 2 wherein said waveguide feed line means is curved having a center of curvature lying along said first axis of rotation.

5. The invention of claim 4 wherein said coaxial feedline is adjustably mounted to said second support means.