Patent ID: 8456283

Claim:
A device for operating an RFID writing/reading device with transmitted signal suppression, the device comprising: the RFID writing/reading device including a transmitter, a receiver with a signal processor, a directional coupler with a first, a second, a third and a fourth port, and an antenna, a reflection modulator connected to the fourth port of the directional coupler, the reflection modulator including a first setting element and a second setting element, wherein the reflection modulator is configured to reflect a copy of a transmitted signal from the RFID writing/reading device, the amplitude and phase of which copy have been weighted, to the directional coupler, and wherein the directional coupler is configured to add the weighted copy of the transmitted signal to a received signal from the antenna; wherein the reflection modulator comprises a signal splitter, a delay line of the electrical length 45° and a first and a second electronically variable resistor as the terminating load, and wherein the first and second electronically variable resistors are each implemented using at least one PIN diode (positive intrinsic negative diode) configured to be operated in the forward-bias range by a direct current.