Phase-Shifted Traveling-Wave-Tube Circuit for Ultrawideband High-Power Submillimeter-Wave Generation

A novel slow-wave vacuum electron device circuit, consisting of a half-period-staggered double-vane array and a high-aspect ratio sheet electron beam, has been conceived for a high-power wideband submillimeter-wave generation. A particle-in-cell simulation, which is based on a finite-difference time-domain algorithm, has shown that this circuit has a very wide intrinsic bandwidth (in excess of 50 GHz around the operating frequency of 220 GHz) with a moderate gain of 13 dB/cm. Moreover, the saturated conversion efficiency is predicted to be 3%-5.5% over the operating band corresponding to an output power of 150-275 W, assuming a beam power of 5 kW. Of particular importance, this structure is based on the TE-fundamental mode interaction, thereby avoiding the complex over moding instabilities that usually cause spurious signal oscillation in conventional high-aspect-ratio structures. This planar circuit has simple 2-D geometry that is thermally and mechanically robust as well as being compatible with conventional microfabrication techniques. This concept is expected to open numerous opportunities in potential applications of versatile electronic devices in the low-millimeter- and submillimeter-wave regions.