Design of Millimeter-Wave High-Power Power Monitoring Miter Bend Based on Aperture-Coupling ⁄

A directional coupler in a miter bend was designed to monitor the microwave power of the transmission line in an electron cyclotron resonance heating (ECRH) system. It is based on aperture-coupling theory and simulation of an electromagnetic (EM) field to design and optimize the 140 GHz high-power directional coupler. In addition, we simulated the double-aperture directional coupler by using three-dimensional (3D) EM simulation software, in which the central frequency is 140 GHz, coupling factor is about −70 dB, and directivity is greater than 17dB. The results show that such a coupler is a viable tool for power measurement in high-power transmission systems.