Design of 30GHz Transition between Microstrip Line and Substrate Integrated Waveguide

This paper proposes a vertical transition between microstrip line and substrate integrated waveguide (SIW) on multilayer low-temperature co-fired ceramic (LTCC) as well as its equivalent circuit model. The transition structure is realized by a shorted via between microstrip line and the bottom of SIW. The equivalent model is derived by calculating the input impedance in waveguide and the simulation result by commercial software Ansoft HFSS. One single transition exhibits more than 30% fractional bandwidth (FBW) with center frequency at 30 GHz for -15 dB return loss and 0.6 dB insertion loss in the operating band.