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Tunable microwave network and application to transmit leakage cancellation circuit in an RFID interrogator

  • US 9,900,060 B1
  • Filed: 05/12/2016
  • Issued: 02/20/2018
  • Est. Priority Date: 05/12/2015
  • Status: Expired due to Fees
First Claim
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1. A RFID interrogator transceiver comprising:

  • an antenna;

    a directional coupler comprising an input port, a transmitted port, a coupled port, and an isolated port, the transmitted port being operatively coupled to the antenna;

    a signal source operatively coupled to the input port to provide an output signal through the antenna;

    a signal receiver operatively coupled to the isolated port to receive an input signal from the antenna;

    a tunable microwave network operatively coupled to the coupled port, the tunable microwave network comprising;

    a phase shifting element operatively coupled to the coupled port;

    a first tunable capacitive element operatively coupled to the coupled port through the phase shifting element in a shunt configuration between the phase shifting element and ground; and

    a second tunable capacitive element operatively coupled to the coupled port, in a shunt configuration between the phase shifting element and ground,wherein at least one of the first tunable capacitive element and the second tunable capacitive element comprises;

    a coarse tunable capacitive element;

    a fine tunable capacitive element subranging the coarse tunable capacitive element; and

    an impedance transforming network,wherein the fine tunable capacitive element is electrically coupled to said tunable microwave network through the impedance transforming network; and

    a control unit configured to adjust a capacitance of the first and second tunable capacitive elements.

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