Novel circulator design using substrate integrated coaxial line

Abstract The contribution of this work is to propose a novel circulator design using the substrate‐integrated coaxial line (SICL) structure. Conventionally, composed three‐dimensional waveguide components, and, in contrast, proposed SICL allows 3‐D be built planar form printed circuit board (PCB) technology. three substrates with two parallel signal strips embedded central tunnel. For better impedance matching, widened section inserted each uniform feedline, and Y‐junction joint on bottom surface middle substrate connected stubs loaded circular disk top substrate. A bandpass filter (BPF) can circulator's branch improve selectivity out‐of‐band isolation. Experiments are conducted verify design. Agreements observed between measured simulated data.