Multilayer compact hybrid coupler based on vertical microstrip transition

This paper proposes a multilayer compact hybrid coupler based on vertical microstrip transition. This transition is a sandwich structure with via hole to connect two microstrip lines in different layer. For designing a compact microwave passive circuit, the microstrip line using via-hole transition is proposed to reduce a size of microwave circuit with long transmission line. For the validation of the microstrip line with via-hole transition, the multilayer hybrid coupler is implemented at center frequency of 2 GHz. The measured performances are in good agreement with simulation results and about 50% size reduction compare to conventional coupler.