Interrogator circuit arrangement
First Claim
1. A radio interrogator circuit for use with a transponder of a type which reflectively modulates a received radio signal, the interrogator circuit comprising:
- a transistor;
an antenna connected to an input of the transistor; and
means for operating the transistor as a reflection amplifier such that it self oscillates and radiates a radio signal from the antenna and simultaneously operates as a mixer to produce an output which is representative of the modulation of a radio signal received by the antenna which has been reflectively modulated by the transponder and wherein the frequency of oscillation of the transistor is determined by the resonant frequency of the antenna.
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Accused Products
Abstract
An interrogator circuit (2) for use with a semi-passive transponder (30) of a type which reflectively modulates an incoming signal (28) is described. The circuit (2) comprises an antenna (4), a transistor (8), a matching network (6) connecting to the antenna (4) to an input of the transistor and means (12, 14) for operating the transistor such that it self-oscillates and radiates power (28) from the antenna (4) and simultaneously acts as a self-oscillating mixer to produce an output (40) which is representative of the modulation of a signal 32 received at the antenna. For an efficient conversion gain the reflection coefficient of the antenna (4) is configured to be low when the circuit is in a stable self-oscillating condition.
37 Citations
13 Claims
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1. A radio interrogator circuit for use with a transponder of a type which reflectively modulates a received radio signal, the interrogator circuit comprising:
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a transistor; an antenna connected to an input of the transistor; and means for operating the transistor as a reflection amplifier such that it self oscillates and radiates a radio signal from the antenna and simultaneously operates as a mixer to produce an output which is representative of the modulation of a radio signal received by the antenna which has been reflectively modulated by the transponder and wherein the frequency of oscillation of the transistor is determined by the resonant frequency of the antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification