A Duplex System of Communications for Microwaves

This paper discusses the properties of a communication system obtained by the use of a single microwave oscillator as both transmitter and beating oscillator of a superheterodyne receiver. The oscillator is stabilized in frequency by an electronic circuit at the frequency of a high-Q cavity and frequency-modulated about this stabilization frequency. The resultant communication sets are capable of very simple duplex communication in pairs, and evidence that he is being received at the other station is given to the operator initiating communication. An application to communication from ground to aircraft, utilizing the very large number of channels available in the microwave region, is discussed. A booster station for a relay link, based on the same principles, is suggested, and an experimental version of the duplex microwave communication set is described.