Dual resonant antenna circuit for RF tags
AssigneeWestinghouse Electric Corp.
InventorsDavid F. Everett, Daniel C. Buck
Life of this patent
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Abstract
A two-way communication system is provided having a stationary device and a portable passive device. The portable passive device has circuitry for storing and transmitting coded information. The stationary member transmits a signal at a first frequency via magnetic field and the portable passive device transmits coded information stored on circuitry provided therein at a second frequency also via a magnetic field. An antenna circuit is provided in the portable passive device having a parallel resonant circuit and a series resonant circuit. The parallel resonant circuit derives operating power from the signal at a first frequency for use in the circuitry provided in the portable passive device. The series resonant circuit transmits coded information at a second frequency.
Claims21
In a two-way communication system having a stationary member and a portable passive member, said portable passive member having circuitry for storing and transmitting coded information, said stationary member transmitting a signal at a first frequency via a magnetic field and said portable passive member transmitting coded information stored by said circuitry in said portable passive member at a second frequency via a magnetic field, the improvement comprising an antenna circuit provided in said portable passive member, said antenna circuit comprising:
- (a) a parallel resonant circuit having a receive antenna for deriving operating power from said signal at a first frequency for use in said circuitry provided in said portable passive member;
- and
- (b) a series resonant circuit having a transmit antenna for transmitting at a second frequency said coded information stored by said circuitry in said portable passive member, said second frequency differing from said first frequency.
In a communication system having an active member and at least one passive member, said active member transmitting a signal at a first frequency via a magnetic field and said at least one passive member transmitting a signal at a second frequency via a magnetic field, the improvement comprising an antenna circuit provided in said at least one passive member, said antenna circuit comprising:
- (a) a parallel resonant circuit having a receive antenna for deriving operating power from said signal at a first frequency for use in said passive member;
- and
- (b) a series resonant circuit having a transmit antenna for transmitting said signal at a second frequency, said second frequency differing from said first frequency.
In a two-way communication system having two active members, one of said active members transmitting a signal at a first frequency via a magnetic field and the other of said active members transmitting a signal at a second frequency via a magnetic field, the improvement comprising an antenna circuit provided in each of said active members, said antenna circuit comprising:
- (a) a parallel resonant circuit having a receive antenna for receiving a signal, said parallel resonant circuit being resonant at the frequency of the signal transmitted by the other active member;
- and
- (b) a series resonant circuit having a transmit antenna for transmitting a signal at a frequency differing from said frequency of the received signal, said series resonant circuit being resonant at the frequency of the transmitted signal.
Dependencies are inferred from the claim text.