Miniaturized bandpass filter using a dual-mode octagonal patch resonator

This paper presents design of a bandpass filter using a novel dual-mode miniaturized octagonal patch resonator. Two slots in orthogonal position are cut on the patch to reduce the resonance frequency. Two circular holes connected by a slot are used to perturb the two degenerate modes of the patch. The proposed filter is 64% smaller compared to an octagonal patch without any slots.