Oscillation characteristics in waveguide-based TWT amplifiers

In any TWT design, understanding of potential spurious oscillation characteristics is critical to achieve optimal amplifier performance and, more importantly, to avoid the unpleasant surprise of discovering problems after the fact. This paper serves to illustrate these oscillation characteristics and to discuss potential mitigation approaches with special emphasis on serpentine/folded-waveguide TWTs. The relationship between folded-waveguide TWTs and coupled-cavity TWTs is also discussed, particularly, with respect to “drive-induced” oscillations.