Passive transponders using acoustic surface wave devices
AssigneeNorthwestern University
InventorMax Epstein
Life of this patent
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Abstract
A passive transponder sensitive to electromagnetic pulses received in the form of surface acoustic waves. The device utilizes a plurality of interdigital transponders each consisting of a metallic deposit on a piezoelectric substrate and serving as an electrode. Transponder deactivation and energy interruption means provide programability and coding.
Claims4
A transponder for receiving and for retransmitting pulsed electromagnetic energy characterized by a frequency range of from about 10 meg. Hz to 1000 meg. Hz and comprising:
- antenna means for receiving and for transmitting a signal of said pulsed electromagnetic energy,
- peizoelectric substrate means remote from said antenna means,
- electrode means carried as an array of electrodes on said peizoelectric substrate means to define therewith an acoustic surface wave device, said device including a plurality of interdigital transducers,
- electrical energy conducting means interconnecting said antenna means with at least one of said interdigital transducers,
- said transducers and said substrate means constituting means responsive to a signal received by said transducers from said antenna means to effect a finite time delay in the conductive travel of said signal along said piezoelectric substrate means, thereby to provide a time-delayed signal,
- said transducers constituting means for transmitting the time-delayed signal to said antenna means,
- said transducers including a circular input transducer propagating radially and an array of output taps disposed in cyclical succession about said transducer,
- said output taps being disposed on a circumference of a circular pattern, and
- means connecting at least one of said output taps to said antenna means,
- whereby said transducers obviate bi-directional radiation and are compatible with each other.
A transponder for receiving and for retransmitting pulsed electromagnetic energy characterized by a frequency range of from about 10 meg. Hz to 1000 meg. Hz and comprising:
- means for receiving and for transmitting a signal of said pulsed electromagnetic energy,
- piezoelectric substrate means,
- electrode means carried as an array of electrodes on said piezoelectric substrate means to define therewith an acoustic surface wave device, said device including a plurality of interdigital transducers, electrical energy conducting means interconnecting said means for receiving and transmitting a signal with at least one of said interdigital transducers.
- said transducers and said substrate means constituting means responsive to a signal received by said transducers to effect a finite time delay in the conductive travel of said signal along said piezoelectric substrate means, thereby to provide a time-delayed signal,
- said transducers constituting means for transmitting the time-delayed signal,
- programming means to program said transducers, said programming means consisting essentially of means to inactivate selectively at least one of said transducers by preventing surface wave travel in a zone adjacent thereto,
- said means to deactivate a transducer comprising pad means overlying said substrate means in a zone adjacent a transducer,
- whereby pressure applied to said substrate means through said pad means renders said substrate means nonconductive to a surface acoustic wave.
A transponder for receiving and for retransmitting pulsed electromagnetic energy characterized by a frequency range of from about 10 meg. Hz to 1000 meg. Hz and comprising:
- means for receiving and for transmitting a signal of said pulsed electromagnetic energy,
- piezoelectric substrate means,
- electrode means carried as an array of electrodes
- on said piezoelectric substrate means to define therewith an acoustic surface wave device, said device including a plurality of interdigital transducers,
- said transducers and said substrate means constituting means responsive to a signal received by said transducers to effect a finite time delay in the conductive travel of said signal along said piezoelectric substrate means, thereby to provide a time-delayed signal,
- said transducers constituting means for transmitting the time-delayed signal,
- programming means to program said transducers,
- said programming means consisting essentially of pressure means to inactivate selectively at least one of said transducers by preventing surface wave travel in a zone adjacent thereto.
- said means to inactivate one of said transducers comprising means selective to connect and disconnect said transducers.
Dependencies are inferred from the claim text.