High impedance transponder with improved backscatter modulator for electronic indentification system

摘要

A transponder 20 for an electronic identification system is disclosed and claimed. The transponder is characterized in that it presents a high input impedance (>400 OMEGA ) at an input thereof which is directly connected to an antenna 22 with a matched high input impedance. The transponder is aimed at improving the voltage recovered on capacitor C2 from an interrogation signal and thus the operational range of the system. The modulator 30 of the transponder is arranged to backscatter modulate the interrogation signal at a modulation depth of less than 80%, preferably in the order of 30%. This also results in an improvement of the operational range of the system. <IMAGE>