A selective frequency reconfigurable bandstop metamaterial filter for WLAN applications

Abstract

In this paper, two designs of bandstop filters are presented and implemented, each one composed of a coplanarwaveguide loaded with a resonator. The first design has a structure with circular resonators, and the second design is afrequency reconfigurable filter with a rectangular spiral resonator and PIN diodes. The designs are based on the use ofmetamaterial to create notch filters for microwave applications. The Nicolson–Ross–Weir method, used to extract therefractive index, is also described to highlight the supernatural electromagnetic characteristic of metamaterials. Fromthe simulation results, the filters exhibit high frequency selectivity via the presence of reflection zeros. In addition, forone or two rejection bands to isolate the WiFi band in a wireless communication system (depending on states of PINdiodes, small dimension, and low in-band insertion loss of better than 1 dB), the bandpass response could be dynamicallytuned to different frequency bands and achieve good out-of-band suppression and linearity. The experimental resultsof the proposed structures are reported; the extracted data are also compared with simulation results, revealing goodagreement.