Folded Waveguide Slow Wave Structure With Modified Circular Bends

Folded waveguide (FWG) slow wave structure with modified circular bends (MCBs) are proposed in this paper. Using Computer Simulation Technology microwave studio code, the cold characteristics were accurately simulated. To solve the band-edge instability, the effect of the MCBs on the dispersion properties, especially in the first-stop band, was investigated, showing that two cutoff frequencies of the first stop-band, together with their corresponding operation modes could be approximately independently determined. Compared with the normal FWG, the structure had higher on-axis coupling impedance. These results predicted that using this structure, the traveling wave tube would achieve a better performance, including small size, high-electron efficiency, and good stability.