Numerical analysis and design for high-performance helix traveling-wave tubes

A new design method has been established for helix traveling-wave tubes having higher output powers (over 100 W) and wider bandwidths (2 to over 4 GHz) and capable of stable operation at frequencies in 10 to over 20 GHz bands. It is based on an analytical technique to consider the influences of the tape width, dielectric and shield barrel in the helix slow-wave circuit simultaneously, and also on an analytical technique to solve problems in regard to backward-wave oscillations at higher output powers, matching input and output sections for wider bandwidths, and undesired coaxial modes caused at operating frequencies above 20 GHz. This method realizes practical design of overall high-performance helix traveling-wave tubes with output powers of 250 W in the 14-GHz band and 20 W in the 30-GHz band and a bandwidth of 2 GHz in the 12-GHz band.