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Intruder detection radar system and automatic nulling antenna array

  • US 4,595,924 A
  • Filed: 07/09/1984
  • Issued: 06/17/1986
  • Est. Priority Date: 10/06/1981
  • Status: Expired due to Term
First Claim
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1. An intruder detection system for a secure area perimeter, comprising:

  • a omni-directional transmitter antenna positioned substantially at the center of a secure area;

    means coupled to the transmitter antenna for causing an electromagnetic continuous wave signal to radiate an annular ring surveillance zone surrounding the transmitter antenna and extending outwardly from the antenna beyond the secure area ring perimeter to an outside ring perimeter;

    a plurality of receiving antennas circumferentially spaced around the secure area ring perimeter at known distances from one another for receiving a portion of a signal reflected by an intruder moving within the annular surveillance zone, and for simultaneously receiving a portion of the direct signal radiated from the transmitter antenna;

    means coupled to the receiving antennas for comparing the reflected signal portion and the directly radiated signal portion received by the antennas and producing an output signal representative of the doppler cycles of phase difference between the reflective signal portion and the directly radiated signal portion;

    means for receiving the phase difference output signals from one or more adjacent antennas and computing tracking data representative of the location, speed and direction of motion of an intruder within the surveillance zone, and including means for displaying intruder tracking data; and

    means for transmitting the phase difference signals from the receiving antennas to the receiving and tracking means.

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