Spectral Distortion of Notch Filtered FM Signals in Saturated Amplifiers

摘要

In certain applications, a narrowband spectral notch may be desired in the output spectrum produced by a wide band interference system. Unfortunately, nonlinear effects in saturating power amplifiers can severely degrade a spectral notch applied at the amplifier input. Theoretical and experimental studies of this phenomenon are presented for notch filtered FM signals. The experiments used a TWT amplifier, and the measured results are presented graphically. The TWT input was an FM signal followed by a notch filter. In specific situations of interest, a perfect notch at the TWT input degrades to a 6-dB notch at the output. This and other results are presented and shown to agree well with theoretical predictions. (Author)