Study of a rectangular coupled cavity extendedinteraction oscillator in sub-terahertz waves

An extended interaction oscillator (EIO) generating 120 GHz wave in sub-terahertz waves is studied by using the three-dimensional electromagnetic simulation software CST and PIC codes. A rectangular reentrant coupled-cavity is proposed as the slow-wave structure of EIO. By CST, the circuit parameters including frequency-phase dispersion, interaction impedance and characteristic impedance are simulated and calculated. The operation mode of EIO is chosen very close to the point where \beta L=2\pi with corresponding frequency 120 GHz, the beam voltage 12 kV and the dimensions of the cavity with the period 0.5 mm, the height 3 mm and the width 1.4 mm. Simulation results of beam--wave interaction by PIC show that the exciting frequency is 120.85 GHz and output peak power 465 W with 12-period coupled-cavity with the perveance 0.17 \muP. Simulation results indicate that the EIO has very wide range of the operation voltage.