Abstract: A wideband VCO including a coaxial cavity with a negative impedance semiconductor diode and a tuning varactor mounted in a center conductor thereof. A variable bias circuit connected to the tuning varactor for tuning the VCO through a predetermined range. An output probe including a coupling varactor in contact with the center conductor. The variable bias circuit is coupled to the coupling varactor to alter the output coupling capacity as the frequency of the oscillator changes so that the output power remains substantially constant.

Abstract: A housing with a microwave cavity and an external opening defined therein, a tubular waveguide section affixed in said opening with a tuning rod slideably positioned therein and an outer end affixed to an outer end of a sleeve mounted in surrounding relationship thereto with the inner end of the sleeve affixed to the housing. The sleeve and tuning rod are formed of dielectric material so that temperature changes on the sleeve cause movement of the rod in the cavity and compensate for changes in the resonant frequency of the cavity while the rod and the waveguide cooperate to prevent radiation leakage.