Design and Microfabrication of an Interaction Circuit for a 0.3-THz Sheet Beam Extended Interaction Oscillator With Multiple-Mode Operation

Normally, the conventional sheet beam extended interaction oscillator (SB-EIO) operates in a single mode and has a narrow tunable bandwidth. To broaden the tunable bandwidth, the concept of multiple-mode operation is proposed and a 0.3-THz ladder-shaped interaction circuit is designed as described in this article. The interaction circuit was manufactured by using the computer numerical control milling technique and cold tested by using a vector network analyzer. Measured and simulated results were in good agreement with each other. Beam-wave interaction simulations with the ohmic loss being taken into account verified the feasibility of the multiple-mode operation and demonstrated that the SB-EIO produced an output power of >91 W in the frequency range of 293.7-294.9 GHz. Compared with the single-mode SB-EIO, the tunable bandwidth of the multiple-mode SB-EIO has increased from 0.3 to 1.2 GHz.