A Novel Wire-Wrap Slow-Wave Structure for Terahertz Backward Wave Oscillator Applications

An innovative wire-wrap structure was applied as the slow-wave circuit for a backward wave oscillator (BWO) operating in terahertz (THz) band. The construction of the device features a periodic fine copper wire, a rectangular ridged waveguide, and a rectangular cavity in the upper cover plate. Based on the novel structure, the performance of the device presented by dispersion characteristic, coupling impedance, and S-parameters was analyzed and optimized in the design process. The electron beam parameters with an outer diameter of 0.26 mm have relatively low accelerating voltage around 1.2 kV and beam current of 0.05 A (the current density is 94 A/cm
²
). Under such conditions, numerical simulation results predict that the novel oscillator is capable of achieving the output peak power in excess of 154 mW and a tunable 3-dB bandwidth over 24 GHz in the range from 324 to 348 GHz. In addition, the machining and assembling methods of wire-wrap structure are another original invention for the physical processing of THz BWO.