Abstract: A communication system comprising a transmitter for radiating a carrier frequency signal, which may be modulated, to a data station. The station includes a rectifier for rectifying the received carrier signal to provide energy to the station elements. A data source at the station produces a data signal representative of the information to be transmitted. A harmonic generator produces harmonics of the carrier signal and the harmonic signal is modulated with the data or information signal. An antenna radiates the modulated harmonic signal to a receiver which demodulates the received signal to extract the information therefrom. Thus, a completely self-contained and economic system is provided, since the carrier signal per se supplies the energy to operate the data station.Additionally, the communication system may include a carrier signal having an address encoded therein and the station may comprise an address decoder so that only a selected addressed station will transmit the desired data at any one time.