A Novel Dual-Sheet-Beam Backward Wave Oscillator Based on Sub-Terahertz Band V-Shaped Orthogonal Grating Waveguide

A sub-terahertz band dual-sheet-beam back-ward wave oscillator (BWO) highlighted with wide tunable bandwidth and enhanced radiation power is presented in this letter. This design includes two key innovations:1) a novel V-shaped orthogonal grating waveguide (VOGW)operating in TM++21high-order mode (++represents the electric field vectors within two beam tunnel regions are in-phase) is proposed, which exhibits higher coupling impedance compared with the traditional OGW; 2) a novel E-plane L-bend over moded coupler with a tapered transition is designed for efficient power extraction of the TM++21mode. For verification, an interaction circuit made of 40-period VOGW and two identical couplers was fabricated, and the measured results agreed well with simulation predictions having considered conduct loss and assembly errors. PIC simulation for this innovative BWOpredicts a stable radiation power of 182.4-317.5 W across246.8-265.6 GHz, demonstrating a power increment of upto 43 W (similar to 15%) in comparison to the OGW based BWO