High frequency roll-bar loop antenna

• US 4,217,591 A
• Filed: 08/27/1979
• Issued: 08/12/1980
• Est. Priority Date: 09/20/1978
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Czerwinski, Watson P.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US06/069,958
• Time in Patent Office: 351 Days
• Field of Search: 343/711, 343/712, 343/713, 343/741, 343/743, 343/744, 343/845, 343/856
• US Class Current: 343/713
• CPC Class Codes: H01Q 1/3275 mounted on a horizontal surface of the vehicle, e.g. on roof, hood, trunk
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/42 with folded element, the folded parts being spaced apart a small fraction of the operating wavelength

Abstract

A vehicular mounted loop antenna which operates as an NVIS radio communicon antenna over one range of frequencies and as a vertically polarized whip antenna over another range of frequencies corresponding to the frequency range of a radio communication set equipped with a conventional whip antenna. A coupling loop of variable area and a transmitting loop are positioned in a common vertical plane on a horizontally disposed base member, with the coupling loop positioned within the transmitting loop. A variable capacitor is in circuit with, and is an integral element of, the transmitter loop to provide resonance over the desired operating frequency range.

Claims

1. A loop antenna for operation on a moving vehicle comprising:

a metallic base mounted longitudinally on top of said vehicle;

a vertically mounted elongated, metallic loop element having one end affixed to said metallic base;

a variable capacitor in series with the other end of said metallic loop element and said metallic base and in conjunction with said metallic base and said elongated metallic loop element forming a closed transmitting loop;

a coupling loop of variable area, coplanar with and at no point exterior to, said closed transmitting loop and inductively coupled thereto; and

an input terminal electrically connected to said coupling loop for feeding a signal into or removing a signal from said coupling loop.

2. The loop antenna of claim 1 wherein said coupling loop is partially comprised of a coaxial cable, slidably mounted on, and electrically connected to, said metallic base thereby providing said coupling loop with a variable area so as to permit adjustment to the input impedance of said loop antenna.

3. The loop antenna of claim 2 wherein said metallic base comprises a U-shaped channel.

4. The loop antenna of claim 3 wherein said closed transmitting loop is approximately rectangular in shape.