Research On Terahertz Low-loss Waveguide Transmission System

Within the system, THZ source determines its performance and the other sub-systems such as the mode converter and transition, decide whether sources’ efficacy can be exerted effectively. So it is of great significance to study THZ transmission system. This paper is about THZ transmission system using at gyro-amplifier experimental System. A waveguide overmode transmission line, which is low-loss and achieve mode converter, has been designed. The main work is as follows.(1) A 220 GHz waveguide mode measurement system was designed to measure the electric field in the waveguide components,this system can test the waveguide components whether meet the design requirements. Using this system to measure the solid state source’s output waves, The result show that the system is normal operating.(2) A TE03-TE01 mode converter with dual-nonuniform period and ripple-wall in circular waveguide and a circular TE0n- Rectangular TE01 mode converter was designed. When using the waveguide mode measurement system to measure the mode, the result show that the mode converter meet the design requirements.(3) The transmission loss of the rectangular waveguide are theoretical studied and experimented. Through measuring mode of rectangular waveguide transition, find the cause of increasing the transmission loss of WR28 waveguide transmission line. After redesigning the rectangular waveguide transition, rectangular waveguide transmission line can meet the design requirements.(4) For the problem of the gyro-amplifier’s microwave window, a box-type window is proposed and studied in theory and experiment. This box-type window let loss under 0.5dB and the band width more than 8GHz. So this box-type window solve problems of the THz wave through a transmission line to gyro-amplifier.(5) Complete the calibration of the CALORIMETER, so it can be used as a power meter for measuring the terahertz low loss transmission system. The result shows the transmission loss of the mode converter, WR28 waveguides and WR10 waveguide transmission line. And the result shows that the power of waves at the transmission system is more than 100 W, this can let the GTWT to do normal work.