Dual band CPW filter using Koch Fractal structure

Abstract

Co-Planar Waveguide (CPW) dual Band Pass Filter (BPF) consisting of Koch fractal structure is etched on the CPW plane. It produces a dual pass band with insertion loss below 0.7dB. Out of band rejection is above -15 db. Bandwidth of the proposed dual band filter can be controlled by varying the gap width of the CPW plane. Resonant frequencies can be varied by varying the size of the Koch curve etched. Also in order to increase the out of band rejection split ring resonators are placed on both sides of the substrate. In order to have a better out of band rejection a bi-layer substrate is taken so as to place SRRs on both sides of the CPW metal layer. Due to the self-similar and space filling properties of fractal structure the proposed structure is compact and it is compatible with PCB and MMIC fabrication technologies, which is of great interest for full integration of communication transceiver front ends.