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Tuned small loop antenna and method for designing thereof

  • US 4,518,965 A
  • Filed: 02/12/1982
  • Issued: 05/21/1985
  • Est. Priority Date: 02/27/1981
  • Status: Expired due to Term
First Claim
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1. A tunable small closed loop antenna, having an input admittance, for transmitting or receiving signals within the VHF and UHF frequency band and tunable over a wide range of resonant frequencies while substantially maintaining impedance matching between the antenna and an antenna feeder line comprising:

  • a loop conductor having a loop area A, circumferential length S and equivalent conductor radius b;

    said loop conductor including feeding taps circumferentially spaced on said conductor wherein said taps are coupled to said antenna feeder line;

    a capacitive element connected in series with said loop conductor for providng a resonant circuit having a loaded Q of not less than 20;

    characterizing in that said loop area, said circumferential length and said equivalent radius are selected so that the ratio of the resonant frequency fo of said resonant circuit and the resonant frequency fm, at which said input admittance is a minimum, is within the range;

    0.5≦

    fo /fm

    3.0whereby the selected values of A, S and b satisfy the following equation;

    ##EQU25## where μ

    is the permeability of the medium and σ

    is the conductivity of the loop conductor, and fm has a value which falls within said range for various resonant frequencies fo existing within a predetermined frequency band.

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