Virtual Magnetic Wall and Its Application in Half-Mode Cavity Resonators

This letter presents a novel methodology for the design and evaluation of virtual magnetic walls (VMWs), specifically tailored for half-mode (HM) cavity resonators. The proposed method overcomes the limitation of small open apertures (OAs) with aspect ratios (ARs) exceeding 10, which is common in traditional HM designs. The approach results in a 37% reduction in both volume and weight compared to traditional full-mode (FM) counterparts. Due to their compact and lightweight nature, HM cavity resonators are particularly well-suited for the development of bandpass filters (BPFs). A four-pole HM BPF was designed, fabricated, and measured. Experimental results confirm the effectiveness of the proposed design and highlight its practical advantages in improving stopband selectivity.