New approach to design a compact triband bandpass lter using a multilayer structure

Abstract

In this paper, a triband bandpass lter is presented using a dual-layer structure. Three H-shaped resonators are utilized in the proposed structure. The rst and third resonators are placed at the top and bottom layers, respectively. The second resonator is divided into two parts: one half is on the top and the other half is at the bottom. The effective permittivity at the rst and second layers is different, resulting in different resonant frequencies. The fabricated triband bandpass lter operates at 5.44/6.98/8.36 GHz, with fractional bandwidths of 6.6%/6%/2.9% and measured minimal insertion losses of 1.9/1.7/2 dB.