Analysis on Resonator Coupling Characteristics of Sub-THz EIA

The resonator coupling characteristics of Sub-THz extended interaction amplifier (EIA) with the grating and subwavelength hole array structure is simulated at the TM31-2π mode. Zero-field points of TM31-2π modes at the center of the beam tunnel promote an effective beam-wave interaction. The operating frequency of the intermediate cavity is 231.28 GHz with characteristic impedance of 207.74 Ω. The return losses of the input and output cavity are both better than 11.32 dB at 231.1 GHz, and the -3 dB bandwidth is 984 MHz.