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Unauthorized entry detection system

  • US 4,638,294 A
  • Filed: 07/23/1984
  • Issued: 01/20/1987
  • Est. Priority Date: 07/25/1983
  • Status: Expired due to Term
First Claim
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1. An unauthorized entry detection system for an automotive vehicle having a passenger compartment of a given size, comprising:

  • oscillator means, adapted to be disposed in said vehicle, for generating an oscillation signal having a predetermined frequency corresponding to said passenger compartment size;

    first antenna means, adapted to be disposed within said passenger compartment and coupled to said oscillator means, for generating an electromagnetic wave inside said passenger compartment to cause said passenger compartment to resonate as a cavity resonator at said predetermined frequency, said electromagnetic wave corresponding to said oscillation signal;

    second antenna means, adapted to be disposed in said passenger compartment, for generating an induced voltage in response to a magnetic component of said electromagnetic wave; and

    detecting means, coupled to said second antenna means, for detecting a change in said induced voltage and providing a detection signal corresponding to said change.

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