for acquiring data of dynamic physical processes via a radio link , a transponder antenna is excited by an electromagnetic exciting wave at the resonance frequency of the transponder antenna , and a back - scattered electromagnetic sensor wave which is modulated by a sensor having an electrical impedance depending on the data to be acquired is received and analyzed . the sensor is directly connected to the transponder antenna such that the sensor changes the electrical impedance of the transponder antenna with every variation of the data to be acquired . the electromagnetic wave which is back - scattered by the transponder antenna is received as the sensor wave at the same time as the transponder antenna is excited by the exciting wave .