Patent ID: 7215239

Claim:
Non-contacting smart card interrogator ( 1 ), in which across a transmission line from an antenna ( 15 ) to a receiver the signal modulation varies between the amplitude and the phase and which comprises a carrier wave generator ( 11 ) and an amplitude demodulation receiver ( 16 ), both being connected to the antenna ( 15 ) through a transmission line 14 , characterized in that to a terminal connecting the amplitude demodulation receiver ( 16 ) to the transmission line ( 14 ), a first end (A) of an eighth-wave transmission line ( 13 ) is connected, and to a second end (B) thereof the carrier wave generator ( 11 ) is connected, and that a signal at the first end (A) and a signal at the second end (B) of the eighth-wave transmission line ( 13 ) are sensed.