An Active, Tracking Microwave Notch Filter Using a Pair of Gunn Oscillators

In this paper, we have designed a signal tracking microwave notch filter at X-band (8 GHz-12.4 GHz) which is tunable. The experimental notch frequency is 9.42 GHz and a 3-dB bandwidth of this filter is 105 MHz. The theoretical response agrees well with the experimental response of this notch filter. The frequency can be tuned by tuning the Gunn oscillators. The Gunn oscillators being injection –locked to the input signal make the notch filter tracking in character.