Design of compact dual-mode bandpass filter based on a new fractal resonator

Abstract

In this paper, a geometrically symmetrical fractal structure is proposed and its generation process is illustrated in detail. A new fractal resonator is produced by etching the proposed fractal geometry on the surface of a dual-mode meandered loop resonator. Based on the third iteration of the fractal resonator, a demonstration dual-mode microstrip bandpass filter is modeled and simulated by using the CST Microwave Studio 2014 electromagnetic simulator. In addition, the mode-splitting characteristic and impact of the perturbation element on the property of the BPF are investigated. In order to better understand the performance of the BPF, the surface current density distribution is also analyzed. The simulation results show that the compact dual-mode BPF operates at 1.65 GHz with a fractional bandwidth (FBW) of 5.1%. The two transmission zeros are located on both sides of the passband, which improves the frequency selectivity.