Design and Analysis of a TE-TEM-TE Co-coaxial Coupling Structure for Multilayer Rectangular SIW

We propose a co-coaxial coupling structure to realize power transmission in double-layer or multilayer rectangular SIWs at any direction. The proposed structure is formed a coaxial structure by adding metallic via and etching circular ring slot on the coupling section of each SIW layer. The shared coaxial coupling structure can support TEM mode for power transmission between different SIW layers. We take double-layer SIWs as an example and simulate its S-parameters from top layer to bottom layer when wave propagation directions (△θ) are designed at 0° (parallel), 90° and 135° with a fixed matching network. The simulated results show that the S11 is below −10dB from 7.6GHz to 10.3GHz; S21 is within –1.1 dB at 0° and 90°, and within −1.3dB at 135° in the operating frequency band.