Sensitivity analysis of a double corrugated waveguide slow wave structure for a 151 – 161.5 GHz TWT

TWTs at D-band (141 – 174.5 GHz) are the most promising solution to provide high transmission power for enabling long range wireless links with high capacity at sub-THz frequency. A D-band TWT was designed in the 151-161.5 GHz frequency band with about 10 W output power. The double corrugated waveguide is adopted as slow wave structure (SWS) for the relatively easy fabrication and alignment in comparison to other SWSs typically used at sub-THz frequency. Due to the short wavelength at D-band, the fabrication requires high precision computerised numerically controlled (CNC) milling machining and tight tolerance control. The sensitivity analysis of performance as a function of the dimensions of a device is an important method to predict in advance how the performance of the device is affected by geometry variations, and also to ascertain the required level of fabrication accuracy to meet the specifications. The sensitivity analysis is also useful to define the best initial dimensions for further optimization. This paper discusses the sensitivity analysis applied to the double corrugated waveguide (DCW) to be used in a 151-161.5 GHz TWT. A broad range of parameters are considered demonstrating the importance of fabrication accuracy and the eventual correction options for a correct functioning. The impact of fillets in the DCW pillars is also evaluated to eventually ease the fabrication requirement.