Design, simulation, and cold test of a W-band double nonparallel staggered grating backward wave oscillator

Zhang, Jin and Alfadhl, Yasir and Chen, Xiaodong and Zhang, Liang and Cross, Adrian W. (2022) Design, simulation, and cold test of a W-band double nonparallel staggered grating backward wave oscillator. IEEE Transactions on Electron Devices, 69 (10). pp. 5814-5818. ISSN 0018-9383 (https://doi.org/10.1109/TED.2022.3195484)

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Abstract

A novel double nonparallel staggered grating (DNPSG) slow wave structure (SWS) is proposed to enhance the coupling impedance in a W-band backward wave oscillator (BWO) driven by a pseudosparksourced sheet electron beam. The DNPSG SWS has been shown a broadband of 72–125 GHz and a higher coupling impedance compared with the traditional double staggered grating (DSG) SWS in simulation. The DNPSG BWO structure consisting of ten SWS units and a broadband output structure is designed and fabricated. In the cold test of the DNPSG BWO, the measured S11 (double of the losses in the DNPSG BWO) is above −10 dB in most of the band, which is satisfactory in the pseudospark-driven high-power device. The hot-test performance of the DNPSG BWO is analyzed by particle-in-cell (PIC) simulation in a beam voltage range of 14–90 kV and a current density range of 1.5–5 × 107 A/m2, obtaining a high output power (max. 190 kW) over an ultrawide tuning band of 38 GHz (75–113 GHz) due to enhanced coupling impedance.

ORCID iDs

Zhang, Jin, Alfadhl, Yasir, Chen, Xiaodong, Zhang, Liang ORCID logoORCID: https://orcid.org/0000-0002-6317-0395 and Cross, Adrian W. ORCID logoORCID: https://orcid.org/0000-0001-7672-1283;