Development of an Improved RF Band-Pass Filter using CSRR Metamaterial Structures on an LCP Substrate

Abstract

For over a decade, academic exploration into the emerging field of metamaterial technology has resulted in advancements in the design of myriad devices such as oscillators, antennas, transmission lines, superlenses, and filters. Unusual electromagnetic properties unique to metamaterial structures have also inspired new work in fields like cloaking technology and nanotechnology. Two such structures that are of interest to RF and microwave engineering applications are the split-ring resonator (SRR) and its dual, the complementary split-ring resonator (CSRR). An RF band-pass filter based on a previous work is designed using a microstrip transmission line on a substrate made of Liquid Crystal Polymer (LCP), a flexible material with desirable RF properties such as a low dielectric constant ε. This transmission line is made of copper and is coupled to a CSRR structure etched into a ground plane below the substrate. The band-pass frequency response is dependent on the physical dimensions of both the microstrip line and the CSRR structure. The proposed filter is designed as a unit cell with a single CSRR structure, and the S-parameters of the filter are simulated for frequencies ranging from 1 GHz to 10 GHz. Both the design and the simulation of the filter are done using HFSS, a commercial simulation tool by ANSYS that uses finite element method (FEM) techniques to solve electromagnetic structures. With an emphasis on improving the upper-band performance, this work seeks to design a compact RF band-pass filter using metamaterial technology that can be applied to non-planar surfaces.