TRANSMISSION LINE LOADED ANNULAR SLOT ANTENNA

• US 3,568,206 A
• Filed: 02/15/1968
• Issued: 03/02/1971
• Est. Priority Date: 02/15/1968
• Status: Expired due to Term

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Austin R. Sisson, Dale W. Milligan, Robert D. Wanselow
• Inventors: Sisson, Austin R., Milligan, Dale W., Wanselow, Robert D.
• Application Number:
  US04/705,841
• Time in Patent Office: 1,111 Days
• US Class Current: 343/750
• CPC Class Codes: H01Q 9/27 Spiral antennas

Abstract

A probe is connected to the bottom of a cavity, and a spiraled conductor is connected to the top of the probe, where the outer turns of the spiral are spaced from the cavity top edges to form an electrically small slot. This antenna is fed from the cavity bottom near the probe by the extension of the center conductor of a terminated coaxial line.

Claims

1. An antenna comprising a conductive cavity, a spiral conductor lying substantially in the plane of the outer opening of Said cavity with the outermost portion of said spiral conductor spaced from the sides of said cavity to form substantially an annular slot, and a conductive probe member electrically connecting the inner end of said spiral to the bottom of said cavity, the nominal diameter of said cavity being only approximately 0.05 wavelength at the opening frequency.

2. Apparatus in accordance with claim 1 including a first transmission line feed connection at the bottom of said cavity and a second such connection at said spiral conductor near said probe.

3. Apparatus in accordance with claim 1 including a first transmission line feed connection at the bottom of said cavity and a second such connection to the side of said probe.

4. Apparatus in accordance with claim 1 including tuning means connected to said spiral conductor.