Load Dependence of Gunn-Oscillator Performance

A detailed analysis of an experimental resonator as a basis for determining the output power and the tuning range of Gunn oscillators as functions of the fundamental resonant-load resistance. Differing n₀L products (1.2 and 4.8x10¹² cm^-2) lead to strikingly different results which are related to the delayed-and quenched-domain resonant modes, respectively. Variations of the second-harmonic frequency termination cause the fundamental output power of Gunn oscillators to change by a factor of up to 5, this change being accompanied by a frequency pulling of a few percent. From detailed impedance measurements it is concluded that the maximum fundamental power occurs if the second-harmonic circuit is tuned near an open-circuit resonance, the total circuit susceptance being somewhat capacitive.