Surface acoustic wave passive transponder having acoustic wave reflectors
First Claim
1. In a passive transponder adapted for use in an interrogation system for transmitting a reply signal containing coded information in response to the receipt of an interrogating signal, said transponder comprising:
- (a) an antenna for converting between electrical energy and electromagnetic energy;
(b) a substrate having a substrate surface defining a plurality of paths of travel for surface acoustic waves;
(c) transducer means, electrically connected to said antenna and arranged on said substrate surface, for converting between electrical energy and surface acoustic wave energy which propagates along said paths of travel, said transducer means comprising a plurality of transducer elements, electrically connected together, for converting said interrogation signal into surface acoustic wave energy, each one of said transducer elements being responsive to produce surface acoustic waves within a specified frequency band upon application of an interrogating signal having a frequency within such band, the frequency bands of at least two different transducer elements being exclusive of each other so that an interrogating signal of a given frequency will excite a specific one of said transducer elements;
(d) a plurality of acoustic wave reflectors arranged on said surface along said paths of travel for reflecting said surface acoustic wave energy back toward said transducer means, said paths of travel extending in at least one direction from said transducer means along at least one common line, wherein said reflectors are arranged along said common line and wherein at least one of said reflectors, closest to said transducer means, reflects only a portion of the acoustic wave energy received, thereby to permit a portion of said acoustic wave energy to pass beneath said one reflector to reach the next reflector along said common line; and
(e) circuit means, connected to said transducer means, for supplying said interrogating signal to said transducer means and for receiving said reply signal from said transducer means.
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0 Petitions
Accused Products
Abstract
A passive transponder for use in an interrogation/transponder system comprises a substrate having a substrate surface defining a path of travel for surface acoustic waves; at least one transducer element arranged on the surface for converting between electrical energy and surface acoustic wave energy which propagates along the path of travel; and a circuit, connected to the transducer element(s), for supplying interrogating signals to the transducer element(s) and for receiving reply signals therefrom. In order to minimize insertion losses in the substrate, acoustic wave reflectors are provided to reflect the surface acoustic waves back towards the transducer element(s).
60 Citations
18 Claims
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1. In a passive transponder adapted for use in an interrogation system for transmitting a reply signal containing coded information in response to the receipt of an interrogating signal, said transponder comprising:
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(a) an antenna for converting between electrical energy and electromagnetic energy; (b) a substrate having a substrate surface defining a plurality of paths of travel for surface acoustic waves; (c) transducer means, electrically connected to said antenna and arranged on said substrate surface, for converting between electrical energy and surface acoustic wave energy which propagates along said paths of travel, said transducer means comprising a plurality of transducer elements, electrically connected together, for converting said interrogation signal into surface acoustic wave energy, each one of said transducer elements being responsive to produce surface acoustic waves within a specified frequency band upon application of an interrogating signal having a frequency within such band, the frequency bands of at least two different transducer elements being exclusive of each other so that an interrogating signal of a given frequency will excite a specific one of said transducer elements; (d) a plurality of acoustic wave reflectors arranged on said surface along said paths of travel for reflecting said surface acoustic wave energy back toward said transducer means, said paths of travel extending in at least one direction from said transducer means along at least one common line, wherein said reflectors are arranged along said common line and wherein at least one of said reflectors, closest to said transducer means, reflects only a portion of the acoustic wave energy received, thereby to permit a portion of said acoustic wave energy to pass beneath said one reflector to reach the next reflector along said common line; and (e) circuit means, connected to said transducer means, for supplying said interrogating signal to said transducer means and for receiving said reply signal from said transducer means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a passive transponder adapted for use in an interrogation system for transmitting a reply signal containing coded information in response to the receipt of an interrogating signal, said transponder comprising:
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(a) a substrate having a substrate surface defining a plurality of paths of travel for surface acoustic waves; (b) transducer means arranged on said surface for converting between electrical energy and surface acoustic wave energy which propagates along said paths of travel; (c) a plurality of acoustic wave reflectors arranged on said surface along said paths of travel for reflecting said surface acoustic wave energy back toward said transducer means; and (d) circuit means, connected to said transducer means, for supplying said interrogating signal to said transducer means and for receiving said reply signal from said transducer means; the improvement wherein said paths of travel extend in at least one direction from said transducer means along at least one common line, wherein said reflectors are arranged along said common line, and wherein at least one of said reflectors closest to said transducer means, reflects only a portion of the acoustic wave energy received, thereby to permit a portion of said acoustic wave energy to pass beneath said one reflector to reach the next reflector along said common line. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification