Inductive antenna coupling for a surface acoustic wave transponder
First Claim
1. Apparatus for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder, said SAW device having a piezoelectric substrate, at least one transducer arranged on said substrate for converting between electrical energy and SAW energy, and two input/output terminals electrically connected to said at least one transducer, said at least one transducer presenting to said terminals a prescribed capacitance at a given frequency range of operation, said apparatus comprising:
- (a) an inductive formed by at least one turn of an electrical conductor, the two free ends of said loop being electrically connected to said two terminals, respectively, and the inductance of said loop being substantially equal to said prescribed capacitance in said given frequency range; and
(b) an antenna capable of receiving and/or transmitting radiation in said given frequency range, said antenna being inductively coupled to said loop, whereby said loop forms a protective DC short circuit across said two terminals and forms a resonant circuit with said SAW device in said given frequency range of operation.
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Accused Products
Abstract
An arrangement is disclosed for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder. The SAW device has two input/output terminals electrically connected to at least one transducer for converting between electrical energy and SAW energy. Such transducer presents to the terminals a prescribed capacitance in the frequency range of operation. An inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device. The inductance of the loop is made substantially equal to the prescribed capacitance at the frequency range of operation, thus forming a resonant circuit with the SAW device. The loop also forms a protective DC short circuit across the two terminals, preventing build-up of static electricity. The inductive loop is inductively coupled to an antenna capable of receiving and/or transmitting radiation in the frequency range of operation.
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Citations
15 Claims
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1. Apparatus for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder, said SAW device having a piezoelectric substrate, at least one transducer arranged on said substrate for converting between electrical energy and SAW energy, and two input/output terminals electrically connected to said at least one transducer, said at least one transducer presenting to said terminals a prescribed capacitance at a given frequency range of operation, said apparatus comprising:
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(a) an inductive formed by at least one turn of an electrical conductor, the two free ends of said loop being electrically connected to said two terminals, respectively, and the inductance of said loop being substantially equal to said prescribed capacitance in said given frequency range; and (b) an antenna capable of receiving and/or transmitting radiation in said given frequency range, said antenna being inductively coupled to said loop, whereby said loop forms a protective DC short circuit across said two terminals and forms a resonant circuit with said SAW device in said given frequency range of operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification