Compact Microwave Triple-mode Bandpass Filter in Planar Technology

Abstract

This paper introduces a novel microwave planar filter design using triple – mode resonator. In order to achieve the filter size reduction we use the multilayer technology. The structure consists of two dielectric layers separated by a common ground plane. The triple – mode resonator consists of two dualmode resonators which are placed on different sides of dielectric layers. Electrical connection between the two resonators is realized by using a via-hole. We use the dual-mode resonator with the short circuited central stub. The filter is designed for the center frequency of 1 GHz. In order to reduce the simulation time for the filter design, we propose a new circuit model, because the circuitlevel simulations are significantly faster than three-dimensional electromagnetic (3D EM) simulations. The 3D filter structure is decomposed into domains and each of them is modeled by a microwave network. The results of the 3D EM simulation and circuit-level simulation are in good agreement.