Four Ports Double Y-Shaped Ultra-Wideband Magneto-Photonic Crystals Circulator for 5G Communication System

This paper presents a novel four ports double Y-shaped photonic crystals circulator with ultra-wide bandwidth in 5G millimeter wave band. Its insertion loss can be designed as low as 0.38 dB at 26.10 GHz while its optimal isolation is up to 74.86 dB at 25.00 GHz. The circulator keeps its isolation above 20 dB from 21.80 to 29.04 GHz. Our simulations also show the relative bandwidth can be effectively broadened to be 28.48% through adding an impedance matching transformer composed of four triangular metal pedestals. We confirmed our theoretical results with a circulator sample made of a triangular-lattice Al2O3 ceramic rod array and ferrite posts. The minimal measured isolation and insertion loss have reach 47.61 dB and 0.80 dB at 25.55 GHz and 26.10 GHz, respectively. The operating spectral region of our sample covers from 24.08 to 28.23 GHz (the relative bandwidth is 15.87%), which is about seven times higher than the best simulated result of 2.5% and fifteen times higher than 1.07%, the published experimental value. Our experimental results are well matched with the numerical simulations. The low loss, high isolation and ultra-wideband characteristics demonstrate that our photonic crystal circulator has potential applications in 5G communication systems.