In order to use maximum dc power for TWT amplifier in satellite, it is desired that the TWT amplifier operates in near-saturation point. However under the up-link jamming the operating point of the TWT amplifier readily falls into the saturation region. In this case it is needed to remove the jamming signal in the IF-stage so that the TWT amplifier does not operate in saturation region. There are several methods in IF-stage jamming rejection; They are AGC, Bandpass filter bank and Hard bandpass limiter methods. The AGC can prevent saturating but worsen the signal-to-noise ratio at the receiver. The performance of the filter bank is good for single-tone and partial-band jamming, but poor for multitone jamming. Finally the hard-limiter method shows good performance for single-tone jamming, but it can not reject partial band and multitone jamming.
In this these, a new IF-stage jamming rejection method is proposed, which comprise hard-limiter and bandpass filter bank. The computer simulation demonstrated that the proposed method has considerable jamming rejection capability under various jamming conditions.
