Pseudo-passive transponder device
First Claim
1. A transponder device for use in an interrogator/transponder system, said device including:
- antenna means capable of receiving a signal from any angle in a first range of angles having predetermined boundaries, without a priori knowledge of the arrival of said signal at said antenna means, and subsequently radiating said signal in a beam centered substantially at said angle from which it was received, wherein substantially all of the energy in said radiated signal is concentrated in a second range of angles which is narrower than said first range of angles; and
signal modification means for modifying said signal after said signal has been received by said antenna means and before said signal has been radiated from said antenna means.
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Accused Products
Abstract
The present invention relates to a wireless transponder system. The transponder system includes a transponder device which is capable of operating over a relatively long range without the need for frequent battery replacements. The transponder device includes both an antenna means and a signal modification means. The signal modification means is operative for modulating an interrogation signal received from a reader device. The modulation means may utilize low power switching components that allow it to operate continuously while drawing very little current from an internal battery. In this way, the battery within the transponder will not become prematurely drained and can last up to substantially the shelf-life of the battery. In one embodiment, the transponder of the present invention utilizes a retrodirective array antenna for achieving increased antenna gain in the direction of a reader device, and therefore increased range, without an associated reduction in effective antenna coverage.
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Citations
37 Claims
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1. A transponder device for use in an interrogator/transponder system, said device including:
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antenna means capable of receiving a signal from any angle in a first range of angles having predetermined boundaries, without a priori knowledge of the arrival of said signal at said antenna means, and subsequently radiating said signal in a beam centered substantially at said angle from which it was received, wherein substantially all of the energy in said radiated signal is concentrated in a second range of angles which is narrower than said first range of angles; and signal modification means for modifying said signal after said signal has been received by said antenna means and before said signal has been radiated from said antenna means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A transponder device for use in an interrogator/transponder system, said device comprising:
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antenna means capable of receiving a signal from an exterior source and subsequently radiating a modified signal to said exterior source; and signal modification means for receiving said signal from said antenna means, modifying said signal, and delivering said modified signal back to said antenna means, said signal modification means including; a signal flow path; and means for continuously and periodically varying the transmission characteristics of said signal flow path regardless of whether said signal is present. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A transponder device for use in an interrogator/transponder system, said device comprising:
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antenna means capable of receiving a signal from an exterior source and subsequently radiating a modified signal to said exterior source; and means for modifying said signal received by said antenna means to create a modified signal, said means for modifying including; means for receiving said signal from said antenna means; means for delivering said modified signal to said antenna means; a signal flow path between said means for receiving and said means for delivering for guiding said signal therebetween; means for varying the transmission characteristics of said signal flow path so that said signal is modified as it flows through said signal flow path; and means for receiving power from an internal battery and for providing said power to said means for varying. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification