Patch antenna having tuning means for improved performance

• US 4,386,357 A
• Filed: 05/21/1981
• Issued: 05/31/1983
• Est. Priority Date: 05/21/1981
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Martin Marietta Corporation
• Inventors: Patton, Paul D.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/265,962
• Time in Patent Office: 740 Days
• Field of Search: 343/700 MS, 343/829, 343/830, 343/846
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 9/0442 with particular tuning means

Abstract

A patch antenna employing a matching stub for improved performance. The patch antenna comprises a conductive patch disposed closely over a ground plane, having a shorting pin shorting the conductive patch to the ground plane at a central point and a coaxial feed line attached to the conductive patch at a point between the shorting pin and the edge of the patch for conducting electromagnetic energy to or from the conductive patch. The matching stub comprises a conductive member extending at least partially between the ground plane and the conductive patch at a point located on the opposite side of the shorting pin from the feed line. Performance is further improved by leaving only a small portion of the inner conductor of the coaxial feed line uncovered by the outer conductor.

Claims

1. In a patch antenna comprising a planar conductive patch disposed closely over a ground plane, having shorting means shorting the conductive patch to the ground plane at a central point and feed means attached to the conductive patch at a point between the shorting means and the edge of the patch for conducting electromagnetic energy to or from said conductive patch, the improvement comprising passive matching means for tuning said antenna to improve its performance, said matching means comprising a conductive member extending at least partially between said ground plane and said conductive patch at a point located on the opposite side of said shorting means from said feed means.

2. The improvement of claim 1 wherein said feed means and said passive matching means are positioned along said conductive patch such that said shorting means is disposed substantially midway between them.

3. The improvement of claim 1, wherein said feed means comprises a coaxial transmission line extending through said ground plane, the center conductor being electrically attached to said conductive patch and the outer conductor being electrically attached to said ground plane.

4. The improvement of claim 3, wherein said outer conductor protrudes through said ground plane and extends part of the distance to said conductive patch whereby the portion of unsheathed inner conductor is shorter than the distance separating said conductive patch and said ground plane.

5. The improvement of claim 3, wherein said conductive member comprises a cylinder of conductive material having substantially the same cross sectional diameter as said coaxial transmission line.

6. The improvement of claim 5, wherein said cylinder is threaded and is screwed through said ground plane towards said conductive patch.

7. The improvement of claim 1, wherein said conductive member is electrically shorted to said ground plane and extends from said ground plane towards said conductive patch.

8. The improvement of claim 7, wherein said feed means and said passive matching means are positioned along said conductive patch such that said shorting means is disposed substantially midway between them.

9. The improvement of claim 8, wherein said feed means and said passive matching means are positioned along said conductive patch equal distances from corresponding edges of said conductive patch.

10. The improvement of claim 1, wherein said passive matching means further includes means enabling adjustment of the extent to which said conductive member bridges the distance between said conductive patch and said ground plane.

11. The improvement of claim 10, wherein said conductive member is substantially cylindrical in shape and said adjustment enabling means comprises threads formed on the outer surface of said member and cooperating threads on the inner surface of a correspondingly sized opening in one of said conductive patch or ground plane, permitting said member to be screwed into or out of said opening and thus permitting variation of the extent to which said conductive member bridges the distance between said conductive patch and said ground plane.