A Miniaturized Bandpass Filter Utilizing Hybrid Configuration

This paper presents a miniaturized bandpass filter (BPF) exploiting the hybrid eighth-mode substrate integrated waveguide (EMSIW) and microstrip-line (MSL) structures. A second-order EMSIW BPF with corner-feed type is exhibited first. In order to enhance the performance of the prototype, two MSL resonators are integrated into two EMSIW cavities to achieve a fourth-order BPF without extra circuit size. Three transmission zeros (TZs) are introduced at the right side of the operating passband. To validate the designed concept, a prototype is thoroughly fabricated and measured. Reasonable agreement has been approached between the simulation and measurement.