Investigation of Frequency-Selective Surfaces for a THz Gyromultiplier Output System

The recent development of some high-power THz vacuum electronic devices calls for the application of space filters such as frequency-selective surfaces (FSSs) and polarization dividers. This paper presents the comparative study of two types of FSSs for a THz gyromultiplier output system, one with high-pass characteristic while the other one with low-pass functionality. Both FSSs are designed, fabricated, and experimentally tested between 200 and 1600 GHz to verify their capability of separating the dual-frequency output from the gyromultiplier. The high-power operation capability of the FSSs is also characterized by taking both the corona discharge and volumetric breakdown into consideration at the frequencies of interest. Based on the comparative study of the performance, the fabrication challenge and the high-power capability between the two FSSs, a generalized conclusion is given regarding the choice of the FSSs for high-power THz application.