A novel microstrip diplexer with a common square ring resonator for WCDMA

In this paper, a novel diplexer with a common square ring resonator for WCDMA system is proposed. A square ring resonator is perturbed by a square patch, and two degenerated modes are excited. Each mode is designed for an individual channel of the diplexer. Then two hairpin resonator is designed and coupled to the common dual-mode resonator. In order to improve the coupling between common resonator and hairpin resonator, non-resonating nodes have been inserted between dual-mode resonator and hairpin resonators. The diplexer is designed and fabricated. Measured results verified the proposed structure of diplexer.