Research on Transition Between Substrate Integrated Waveguide and Microstrip Line

Abstract

Substrate integrated waveguide (SIW) was a new microwave transmission structure which appeared ten years ago, it consists of two rows of metal holes tightly arranged, making the electromagnetic wave propagation limited in the area of SIW. The SIW structure combines the high quality factor of the rectangular waveguide with the advantages of the microstrip structure such as easy integration, easy processing, small size and low cost. It has now been widely used in microwave and millimeter wave circuits. In microwave millimeter wave system, the circuit is not completely made up of SIW structure, but of a large amount of microstrip lines or other forms of circuits. In order to facilitate the integration of SIW and microstrip structure, it is necessary to design a transformation structure to realize the transition between SIW and microstrip line. Therefore, the conversion between SIW and microstrip line is the key to the application of SIW and millimeter wave circuits. In order to improve the transmission efficiency between substrate integrated waveguide and microstrip line, this paper describes the basic principle and structure of substrate integrated waveguide and microstrip line transition, through the analysis of the impedance matching and software HFSS simulation, discusses the SIW—microstrip line direct transition structure, type structure and convex concave type transition structure, and studies the influence of parameter change on the transmission performance, finally designs the rounded corners and chamfering two gradient structure. The simulation results after optimization showed that in the range of 5.95–6.67 GHz, the insertion loss is −0.3–−0.6 dB, the return loss is less than −20 dB, and the bandwidth is 689 MHz, achieving good transmission performance, which can be widely used in the design and testing of SIW devices.