An active device comprises an IMPATT diode arranged on a heat sink block, a coaxial cavity resonator whose inner conductor of coaxial line is the supply means for supplying a DC bias to the oscillator element, a resonance circuit formed of that part of the inner conductor which is around the oscillator element, a step waveguide to which an output from the resonance circuit is transmitted through an output coupling part formed of the inner conductor and the outer wall of the coaxial cavity resonator, and a short piston for closing that end of the waveguide which is an open terminal of minimum height. The open terminal is electromagnetically coupled with the output coupling part and has its height made smaller than the size of a standard waveguide.
A source of microwave-frequency electromagnetic energy of a specific desired frequency is generated by a device that utilizes a filter network to absorb energy of unwanted frequencies and couples energy of the desired frequency into a tunable ridge waveguide. The filter network is designed into the DC bias conductor to increase oscillator efficiency.
