Abstract: A signal transceiver for transmitting a carrier signal to a transponder and receiving a modulated data signal returned by the transponder is provided. The signal transceiver includes a transistor with a base, a collector and an emitter, a controller being electrically connected to the base and providing a controlling signal for turning on the transistor, an oscillation source being electrically connected to the collector for providing the carrier signal, a capacitor being electrically connected to the base and the oscillation source for forming an oscillation circuit, and a resonator being electrically connected to the collector for transmitting the carrier signal to the transponder and receiving the modulated data signal returned by the transponder, and outputting a demodulated data signal through the emitter.