Prediction of phase noise in a TWT based transmitter for a pulsed Doppler radar

In traveling wave tube amplifier (TWT) based transmitters the velocity modulation process inside the TWT gives rise to unwanted phase variations in the RF termed as phase modulation. These phase variations can be detected in the return echo of the pulsed Doppler radar leading to a risk of false targets being detected. This paper presents the relation between the RF phase variations and the ripple component of the high voltage biasing supply of the TWT. It then presents a method of predicting the phase noise after studying and modeling the parameters responsible for it by simulating the phase noise on the personal computer. This simulated phase noise is then compared with the performance of the actual working system