Dispersion and Dielectric Attenuation Properties of a Wideband Double-Staggered Grating Waveguide for Subterahertz Sheet-Beam Traveling-Wave Amplifiers

The dispersion and dielectric attenuation characteristics of a double-staggered grating waveguide (DSGW) are two crucial features related to the output characteristics of a sheet-beam traveling-wave amplifier and have been previously studied by using theoretical analysis and simulations. In this work, these two characteristics are both experimentally studied. Two ${H}$ -band (220-325 GHz) DSGW circuit prototypes with and without dielectric attenuators made of the BeO-TiO2 composite ceramic were machined by using nanocomputer numerical control milling. Experimental studies of the dispersion property were performed successfully where the measurement results were in good agreement with those predicted by simulations, exhibiting a wide passband of 70 GHz (230-300 GHz). The measured transmission coefficient has been decreased from -5 to -55 dB after the introduction of dielectric attenuators, experimentally verifying the feasibility of the adopted methodology. The effects of the variations of dispersion relation and transmission loss on the beam-wave interaction stability were also investigated.