Method and apparatus for reducing residual RF power in a transmitter/receiver antenna
First Claim
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1. A method for interrogating a transponder using a single transmit-receive antenna, comprising the steps of:
- generating a first transmission signal having a first phase for a time interval which energizes said transponder;
generating a second transmission signal after said first transmission signal having a second phase which reduces residual energy in said antenna; and
receiving an RF signal on said antenna from said transponder.
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Abstract
A method and apparatus for interrogating a transponder using a single transmitter-receiver antenna transmits an interrogation signal to the transponder. The transmit signal has two segments; a first segment for energizing the transmitter-receiver antenna and a second segment having a second phase for cancelling energy in the transmitter-receiver antenna. The amount of energy is reduced before the transponder transmits a response signal.
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Citations
19 Claims
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1. A method for interrogating a transponder using a single transmit-receive antenna, comprising the steps of:
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generating a first transmission signal having a first phase for a time interval which energizes said transponder; generating a second transmission signal after said first transmission signal having a second phase which reduces residual energy in said antenna; and receiving an RF signal on said antenna from said transponder. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for reducing residual power in a transmitter-receiver antenna, comprising:
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antenna means for transmitting and receiving RF signals; driving means, electrically connected to said antenna, for providing energy to said antenna; and control means, electrically connected to said driving means, for controlling the operation of said driving means by generating a transmission signal; said transmission signal having two segments, a first segment having a first phase followed by a second segment having a second phase different from said first phase so that said second segment reduces the energy remaining in said antenna means after said first segment. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification