Abstract: The invention comprises a microwave oscillator using a stripline circuit. The active device utilized in the oscillator is a bipolar transistor. A microstrip circuit is coupled to the emitter of the transistor while the collector is coupled to ground. This generates a negative impedance characteristic at the base of the transistor at the operating frequency. The operating frequency is determined by a varactor which is series tuned with an inductor. The impedance of the series tuned circuit is transformed to match the input impedance of the transistor by a microstrip circuit. Microstrip isolation circuits are utilized to couple appropriate bias signals to the emitter and the base to establish the proper operating point for the bipolar transistor. The output signal is taken from the base circuit of the transistor through the series combination of two microstrip circuits and a capacitor. A second varactor is loosely coupled to the base circuit of the transistor to provide for fine tuning.

Abstract: A pulsed microwave power amplifier for radar transmitters having a class B operated first stage field effect amplifying transistor, which is gate biased to pinch-off in the absence of an input pulse is disclosed. The drain current pulse induced in response to the input RF signal appears as a voltage, which is stepped up through a Ruthroff transformer to turn on a bipolar transistor which switches a gate of a second stage field effect transistor from pinch-off voltage to a voltage corresponding to the drain current substantially equalling 1/2 I.sub.DSS to operate class A for the second stage of amplification. A third stage of amplification may be utilized, wherein its field effect transistor, which is also biased to pinch-off is operated in response to the amplified signal.