Interrogator of electronic recognition system

Application Number: 00107328
Application Date: 2000.05.08
Publication Number: 1273402
Publication Date: 2000.11.15
Priority Information: 1999/5/7 ZA 99/3169
International: G06K9/62
Applicant(s) Name: Hup Sensor Holding Ltd.
Inventor(s) Name: Kristof Goden. Jevis. Tena;David Edwen. Procter
Patent Agency Code: 11219
Patent Agent: gu huimin
Abstract To provide a much higher transmission energizing signal power level by operating a first demodulator so as to demodulate a second signal received through an antenna while using the reflection of a first signal from that antenna. SOLUTION: An interrogator 12 has an energizing signal transmitter 20 connected through a transmission line 22 in the form of a strip line to a transmitting/receiving antenna 16. An energizing signal is propagated in a first direction, namely, forward direction A along with the transmission line 22 so as to be transmitted by the transmitting/receiving antenna 16. Further, the interrogator 12 has a receiver 23 provided with first and second balanced demodulators 24 and 26 inductively coupled through a directional coupler provided with coupling lines 28.1, 28.2, 30.4 and 30.2 to the transmission line 22. This coupler is operated so as to couple the reflection from the transmitting/ receiving antenna 16 in a part of a signal, which includes a response signal propagated in a second direction, namely, backward direction B and received from a transponder, and the energizing signal to the first and second balanced demodulators 24 and 26.