HIGH ISOLATION DIPLEXER USING THE HYBRID COAXIAL AND MICROSTRIP RESONATORS FOR RF/MICROWAVE COMMUNICATION SYSTEMS

Abstract

One of the major passive components, which affected the performance of broadband RF/microwave communication systems, is the diplexers. This paper presents a new approach for designing a high selectivity diplexer, which is based on compact and high unloaded quality factor hybrid coaxial and microstrip resonator bandpass filters (BPFs). Additional transmission zeros (TZs) on both sides of the passband response, which are created by mixed electromagnetic (EM) coupling scheme, can be easily realized to high isolation of the proposed diplexer. A designed diplexer prototype at center frequencies 2.6 and 3.1 GHz with 3-dB bandwidth of 220/180 MHz, respectively, is designed and simulated by HFSS software. The proposed diplexer has been exhibited to have excellent filtering selectivity, low insertion loss, and improved channel-to-channel isolation.