Simulation study on dispersion shaping and harmonic suppression in traveling-wave tubes

This paper describes the investigation of broadband interaction and harmonic suppression. A special dispersion shape used in broadband traveling-wave tubes (TWT) is obtained. The and simulation studies of negative dispersion are presented. On the basis of these studies, a broadband TWT used in microwave power module (MPM) is designed. Compared with the old TWT with flat dispersion, the new one with negative dispersion decreases the second harmonic content about 10 dB and improves the fundamental efficiency about 5% at the low end of the band. The modified TWT is fabricated and the simulation results meet the measurements very well.