A HIGH BAND ISOLATION AND WIDE STOPBAND DIPLEXER USING DUAL-MODE STEPPED-IMPEDANCE RESONATORS

Abstract

In this paper, a high performance diplexer is designed and fabricated for Global Positioning System (GPS) and wireless local area network (WLAN) applications simultaneously. The diplexer mainly comprises two dual-mode ring bandpass filters (BPFs), operated at 1.575 GHz and 2.4 GHz, respectively. By using the stepped-impedance resonator (SIR) in the BPFs, the size reduction and wide stopband from 2.8 GHz to 6 GHz are obtained. Moreover, several transmission zeros are located at the passband edges, thus improving the passband selectivity. Due to impedance matching between two BPFs, a high