An integral-polepiece folded-waveguide slow-wave circuit for high-power millimeter-wave TWTs

There is presently much interest in low-cost, thermally rugged, slow-wave circuits that can be utilized in high power millimeter-wave TWTs. This interest includes both innovations of the design and fabrication of traditional helices and coupled-cavities as well as new circuit concepts. A program to develop a high power Ka-band TWT at Litton EDD resulted in the investigation of a novel, low-cost, lightweight, thermally rugged, integral-polepiece folded-waveguide circuit that seems well suited for millimeter-wave TWTs. Circuits built into experimental Ka-band TWTs produced peak power levels above 800 watts, gain levels of up to 10 dB/in, and average power levels of hundreds of watts.<>