Sensor system

摘要

Sensor system comprising an RF transceiver (1) which is arranged to transmit an RF signal (2) and to receive reflections (3) of the transmitted RF (radio or radar) signal. The sensor system comprises a transponder (4) having an antenna (5) which is tuned to the RF signal's frequency. The antenna is connected to a switching element (6) which is arranged to switch the antenna's terminating impedance between at least two values and which switching element is controlled by digital control means (7, 10). The control means are e.g. controlled by voice (9). The antenna (5) preferably is a micro strip or printed antenna or a micro strip patch antenna or patch antenna, e.g. comprising an insulated carrier (13) having a first conductive layer (11) on one side and a second conductive layer (12) on the other side.