How does a gunn source work?
A Gunn source is both a transmitter and a receiver at the same time. It transmits by generating microwave energy in its metal cavity by the action of the gunn diode, and this power comes out of the waveguide exit into the horn antenna. It receives at the same time by using this same gunn signal as a local oscillator and mixing with the incoming receive signal from the other station to produce an I.F. frequency determined by how far each gunn frequency is separated from the other gunn frequency. Example: If one station operates on 10.300 ghz, and the other station operates on 10.370 ghz, then the I.F. frequency on each end is the difference, or 70 mhz! This I.F. frequency comes out of the schottkey mixer diode, which is also contained in almost all gunn sources. From this I.F. output, the receive signal is sent to an I.F. amplifier and detector for use.
