Millimeter-wave microstrip diplexer using elliptical open-loop ring resonators for next generation 5G wireless applications

Design of millimeter-wave microstrip diplexer using elliptical open-loop ring resonators (OLRRs) for the next fifth generation (5G) wireless applications, is presented in this paper. The proposed design consists of two 14-GHz and 28-GHz band pass filters (BPFs). Each BPF consists of elliptical OLRRs that couple two microstrip lines. The geometrical parameters of both BPFs can easily adjust the passband and stopband frequencies to the desired frequencies. The proposed elliptical-shaped OLRRs show good broadband characteristics. The longer OLRR is responsible for achieving passband at the lower resonant frequency of 14-GHz while the shorter OLRR is used to generate a 28-GHz resonant frequency. The proposed diplexer has good return losses and insertion losses at the two resonant frequencies of 14-GHz and 28-GHz.