Abstract
A small circulator with a coplanar waveguide structure was confirmed to have nonreciprocal transmission characteristics by a high-frequency electromagnetic simulation based on a three-dimensional finite element method. The circulator consists of a hexagonal YIG ferrite substrate and a Y-junction with coplanar waveguide transmission lines. Operating at 7 GHz, the circulator has an insertion loss|S21|of 0.69 dB, isolation |S31| of 32.7 dB, retum loss |S11| of 32.2 dB, and bandwidth of 77 MHz. The nonreciprocal operation of the circulator is attributed to the wavy nonuniform distribution of the electric field in the YIG ferrite substrate.
