Low-Loss Transmission Line for a 3.4-kW, 93-GHz Gyro-Traveling-Wave Amplifier

In this article, a transmission line system for the propagation of millimeter-wave radiation is presented. The full system includes a TE
₁₁
-to-TE
₀₁
mode converter, waveguide tapers, miter bends, and many straight sections. The design of each of these components is described, and the optimized simulation results are given. The mode converter shows a greater than 96% mode conversion efficiency that can be achieved over a 2% bandwidth at the W-band. The miter bends demonstrate a transmission loss of 0.04 dB each over the same bandwidth when they are configured to introduce a mixture of higher order waveguide modes before the reflecting surface. An example transmission line system with a propagation length of 20 m, inclusive of four 90° bends with an oxygen-free high conductivity (OFHC) copper waveguide material, was studied over a 90-96-GHz frequency range and showed a 0.84-dB transmission loss at 93 GHz.