High-selective wideband combline filters based on miniaturized-engineered resonators, inter-resonator tapped-in coupling, and probe coupling

In this work, the design of wideband-miniaturized cavity combline filters with enhanced selectivity is presented. These filters are designed using recently introduced design concepts based on miniaturized mushroom resonators and tapped-in coupling. The inter-resonator tapped-in coupling mechanism is a simple but effective solution that solves the challenges of creating a strong coupling between adjacent miniaturized resonators. The structure of a probe that creates a strong capacitive cross coupling is introduced in-between mushroom resonators to enhance selectivity. Filters examples are presented to show the performance of proposed probe coupling structure and the simplicity to design miniaturized wideband-high-selective bandpass filters.