Abstract
High power, multi-channel microwave rotary joint plays a critical role in radar systems. This thesis proposes the high power designs of circular TE01 and TM01 mode converters respectively. Due to the orthogonality of the field profile between TE01 and TM01 mode, a pair of the high power, dual-mode converters with back-to-back connection can be developed into a high isolation, dual-channel microwave rotary joint. HFSS is employed to separately design every component. Considering the effect of the cutoff frequency, TM01 wave must pass through the cutoff section of the TE01 mode converter. The connecting section is important for the converting efficiency, the operating bandwidth, and the isolation for the dual-mode converter. A gap for implanting a bearing exists in the middle channel of the rotary joint, therefore, a microwave choke is designed to prevent the leakage of TM01 wave. The experimental result yields a broad -1-dB transmission bandwidth of 15% for both TE01 and TM01 channels. The operating bandwidth for dual channels is highly overlapped with a high isolation of -50-dB between the channels. The transmission efficiency is independent of rotated angles since the field profile of TE01 mode and TM01 mode are azimuthal symmetric.