Performance Evaluation and Experimental Study of a 0.34-THz Folded Waveguide Sheet Beam BWO

Terahertz (THz) backward wave oscillators (BWOs) hold immense potential for a broad range of industrial and military applications. This study presents a comparative analysis of 0.34 THz sheet beam (SB) and circular beam (CB) folded waveguide (FWG) BWOs. We examined the design, simulation (CST MWS and PS, HFSS), and performance, revealing that sheet beam BWO outperforms circular beam BWO in terms of interaction impedance, power, efficiency, and bandwidth. Under 20 kV beam voltage and 10 mA beam current conditions, sheet beam BWO achieves 0.47 \(\Omega \) $\mathrm{\Omega }$ (0.34 THz) interaction impedance, 0.65 W output power, and a bandwidth of approximately 12 GHz, surpassing the 0.18 \(\Omega \) $\mathrm{\Omega }$ , 0.23 W, and 8.5 GHz values of circular beam BWO, respectively. Furthermore, this study encompasses the fabrication and thorough characterization of the sheet beam BWO’s slow-wave structure. Experimental validation confirms its effectiveness, with measured \(S_{11}\) $S_{11}$ demonstrating reflection below \(-\) $-$ 10 dB and \(S_{21}\) $S_{21}$ exhibiting transmission above \(-\) $-$ 2 dB.