Loop antenna with integral tuning capacitor

• US 5,072,233 A
• Filed: 07/20/1990
• Issued: 12/10/1991
• Est. Priority Date: 07/20/1990
• Status: Expired due to Fees

• Current Assignee: Gary R. Zanzig
• Original Assignee: Gary R. Zanzig
• Inventors: Zanzig, Gary R.
• Primary Examiner(s): Wimer, Michael C.
• Application Number:
  US07/556,556
• Time in Patent Office: 508 Days
• Field of Search: 343/743, 343/744, 343/748, 343/866
• US Class Current: 343/744
• CPC Class Codes: H01Q 7/005 with variable reactance for tuning the antenna

Abstract

Disclosed is a tunable loop antenna (20) in which the antenna tuning capacitor (36) is an integral component of the antenna structure. In each disclosed embodiment, the loop antenna is of square configuration with the ends of the conductor (22) that forms the antenna loop being spaced apart from one another. Capacitor plates (38 and 40) extend orthogonally from and coaxially surround each end of the loop conductor to thereby define a parallel plate capacitor in which spacing between the capacitor plates and, hence, the resonant frequency of the antenna is controlled by flexure of the antenna structure. Suspended between the capacitor plates is a dielectric plate (48). Dielectric grease (54) fills the gaps between the dielectric plate (48) and capacitor plates (38 and 40). A remotely operable motor-drive unit (54) facilitates tuning the antenna to a desired frequency.

Claims

1. An antenna comprising:

a conductor formed in a loop, said conductor having first and second ends positioned in spaced-apart juxtaposition with one another, said loop exhibiting flexure that allows the spacing between said first and second ends of said conductor to be varied;

first and second capacitor plates respectively mounted in electrical continuity with said first and second ends of said conductor;

a dielectric plate, said dielectric plate being positioned between said first and second capacitor plates with gaps being formed between said first and second capacitor plates and said dielectric plate;

a viscous dielectric gel that is adherent to said first and second capacitor plates and is disposed between said first and second capacitor plates and said dielectric plate; and

means for flexing said loop formed by said conductor to vary the spacing between said first and second capacitor plates and thereby tune said antenna to a desired operating frequency.

2. The antenna of claim 1, wherein the dielectric constant of said dielectric plate is substantially equal to the dielectric constant of said dielectric gel.

3. The antenna system of claim 1, wherein said dielectric plate extends outwardly beyond the periphery of said first and second capacitor plates and wherein said viscous dielectric gel that is disposed between said first and second capacitor plates extends outwardly beyond the periphery of said first and second capacitor plates.

4. The antenna of claim 1, further comprising a spring member, said spring member being mounted to said antenna for establishing a restorative force to urge said first and second ends of said conductor toward one another when said means for flexing said loop forces said first and second ends of said conductor away from one another.

5. The antenna of claim 4, wherein said spring member is an elastic band.

6. The antenna of claim 1, wherein said means for flexing said loop formed by said conductor includes a motor-drive assembly, said motor-drive assembly being mounted to said antenna and including a drive rod for pushing said first and second capacitor plates away from one another.

7. The antenna of claim 1, wherein said means for flexing said loop formed by said conductor to vary the spacing between said first and second capacitor plates includes a motor-drive unit, said motor-drive unit including a reversible motor and a drive shaft that is rotated by said reversible motor, said drive shaft extending through openings in said first and second capacitor plates, the opening in said first capacitor plate including threads, said drive shaft including a threaded region engaged with said threads of said opening in said first capacitor plate, said second capacitor plate including means for urging said second capacitor plate toward said first capacitor plate when said drive shaft is rotated in a first direction and for urging said second capacitor plate away from said first capacitor plate when said drive shaft is rotated in the opposite direction.

8. A tunable antenna of the type including a conductor, said conductor having first and second ends and being formed as a substantially planar loop with said first and second ends of said conductor being spaced apart from one another, said tunable antenna further including a pair of first and second capacitor plates that respectively extend outwardly from and surround said first and second ends of said conductor, said tunable antenna being characterized in that said substantially planar loop exhibits a spring-like characteristic that allows the spacing between said first and second capacitor plates to be varied by flexing said loop in a manner that urges said first and second capacitor plates toward and away from one another;

said tunable antenna being further characterized by a dielectric plate that is supported between said first and second capacitor plates and by a dielectric gel that is disposed between said first and second capacitor plates and said dielectric plate.

9. The tunable antenna of claim 8 further characterized in that said dielectric plate extends outwardly beyond the periphery of said first and second capacitor plates and in that said viscous dielectric gel that is disposed between said first and second capacitor plates and said dielectric plate extends outwardly beyond the periphery of said first and second capacitor plates.

10. The tunable antenna of claim 9 further characterized in that a motor-drive unit is mounted to said tunable antenna for selectively moving said first and second capacitor plates toward and away from one another to thereby tune said tunable antenna to a desired operating frequency.

11. The tunable antenna of claim 8 further characterized in that flexing said loop formed by said conductor to urge said first and second capacitor plates toward and away from one another is the sole means available for tuning said tunable antenna to a desired operating frequency.