This paper presents a compact multilayer hybrid coupler based on a microstrip viatransition and short transmission line with a capacitor on each side to reduce circuit size. The microstrip via-transition is connected to two microstrip lines in different layers to configure a sandwich structure. To reduce the passive component circuit size, the design method uses a microstrip via-transition and a short transmission line with capacitors on each side. To validate the microstrip via- transition and short transmission line with capacitor, a multilayer hybrid coupler is implemented at a center frequency of 2 GHz. The measured characteristics agreed well with the simulation results, and above 90% circuit-size reduction compared with conventional couplers was realized.
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