Study Of The Compact High Direction Rectangle Waveguide Directional Coupler

Directional coupler as one kind of microwave passive components are widely used in microwave and millimeter wave circuit system. The most important characteristic of the directional coupler is that it can redistribute the microwave energy directionally, according to the specific needs of the different microwave system this kind of redistribution may choose different design to meet the demand. Because the directional coupler has the function of distributing microwave energy directionally, so it was mainly applied in the microwave system for on-line measurement or in the radar system for reflection monitoring or in the broadband system for high power attenuation.In recent years, with the overall development of microwave technology and the upgrade of processing technology, the demand for the directional coupler has changed. In order to meet these demands, a lot of scholars and engineers in the microwave field are developing new kind of directional coupler. The types of directional coupler also has been enriched and developed in this period of time. For example, from the early time using the waveguide as the directional coupler’s transmission system transfer to using a more compact and easier processing like the micro-strip or strip-line as the transmission system, or from the small aperture coupling to the porous array coupling, or from the parallel lines coupling to branch line coupling. We can say that the development of the directional coupler is always accompanied by the development of microwave system. However, many early experimental directional coupler are unable to meet our demands including the main performance index, the overall product volume and the usability. Therefore, the research on the design of a directional coupler with excellent performance, compact structure and usability still has important significance.This paper mainly studied the waveguide directional coupler and designed a H-plane high compact rectangular waveguide directional coupler. Firstly, study the concept and developing history of the directional coupler to gain a further understanding of the research significance and the research status of directional coupler. Secondly, based on the study of small aperture coupling theory and phase superposition theory to gain the solid foundation for the follow-up design of waveguide directional coupler. Before specific design of directional coupler is carried on, a large amount of verification modeling simulation and research on the parameters which may affect the performance of the directional coupler have been done. At last, through 3D electromagnetic simulation software CST to establish the model of directional coupler. Through continuous optimization and adjustment we finally designed a high performance H-plane compact high direction rectangular waveguide coupler. And this H-plane compact high direction rectangular waveguide coupler has been processed and tested. The final test results show that the directional coupler’s reflection within 6.57 GHz to 6.57 GHz frequency reached- 26 dB, the coupling is 20 dB ? 1.5 dB and direction reached 33 dB.