Phase-locked millimeter-wave two-port second-harmonic Gunn oscillators

Two-port harmonic oscillators have been developed which are suitable for voltage-controlled-oscillator (VCO) operation in frequency stabilized systems. Two oscillator designs are presented. The first has a fundamental frequency cavity located above the harmonic output cavity and the fundamental is coupled by means of the Gunn device bias-line filter. The second design is an in-line structure which uses a waveguide taper as the filter element separating the fundamental and harmonic frequency components. The latter design is a translation of the first oscillator concept onto a single plane, so that the prospect of an integrated monolithic version is conceivable. The performance of the oscillators is discussed, and a demonstration of their use in a heterodyne phase-locked loop control system is presented