Electromagnetic wave amplification by Gunn diodes with moving domains

Attention is given to the amplification of an 8-mm microwave signal (in the 32-37 GHz frequency range) by Gunn diodes with frequencies in the centimeter range from 8 to 30 GHz. Values are presented for output power as a function of input power and for the dependence of gain on the damping introduced in the transit-oscillator resonator. The low-signal amplification of a microwave signal at a frequency above transit frequency (with the simultaneous generation of a transit oscillation) indicates that a sample with moving domains has a dynamic negative differential conductivity at frequencies above the transit frequency. The increase in gain upon a decrease in transit oscillation amplitude shows that negative conductivity increases with an increase in the relative time spent by the domain in the sample. Low transit-oscillation amplitudes are best for maximizing gain.