Synthesis Design of SEMCP Filters Based on HMPRs and Hybrid Resonators With Nonuniform $Q$ Factors

In this article, we discuss the synthesis and design of separate electric and magnetic coupling path (SEMCP) bandpass filters (BPFs) based on half-mode patch resonators (HMPRs) and hybrid resonators with nonuniform $Q$ factors. We investigate a novel coupling structure as a universal coupling module and compare it with the traditional SEMCP structure based on stepped impedance resonators (SIRs). HMPR offers several advantages over SIRs, including higher $Q$ factor, complete control over the location and number of transmission zeros (TZs), and the ability to enable compact BPF designs with minimal sacrifice to performance. To demonstrate these advantages, we study the generation and regulation mechanism of TZs based on HMPRs and design three filters using HMPRs and hybrid resonators with different $Q$ factors. We then fabricate three prototypes using substrate-integrated suspended line (SISL) technology and compare the measured results with the simulated results, confirming the effectiveness of our design methods.