Abstract: Based on the principle of "electronically tuning the fundamental frequency and extracting the second harmonic",the paper proposes a circuit model for the wideband series varactor-tuned harmonic oscillator. At W-band the electronic tuned bandwidth of 15% is achievevd within which the minimum power is 5mW and the maxmum over 17mW. The electronic tuned bandwidth of Dyer 5mW is found to be 13GHz.

Key words: millimeter-wave, Gunn diodes, varactor-tuning, harmanic oscillators