Frequency Tuning of TRAPATT Oscillators Using Ferrimagnetic Resonators

The fundamental frequency of a pulsed TRAPATT S-band oscillator on an alumina MIC has been tuned electronically by changing individually the loading of the second and third harmonic terminations. This was realised with modified YIG polycrystalline spheres, (to overcome limiting), semi-loop coupled in shunt with an Evans type, TDT, TRAPATT circuit via an open circuited quarter wave transmission line at the harmonic frequency. Pulsed output powers of 40 W with harmonic tuning of the fundamental frequency in excess of 125 MHz (5%) with a power variation of ±0.2 dB have been measured.