Metamaterial-Inspired Compact Single and Multiband Filters

Abstract

In this paper, Compact bandpass filters have been designed. A single bandpass filter was designed using novel triple concentric complementary split-ring resonators placed along the microstrip line in the ground plane. Gaps and via were placed on the microstrip line to control electromagnetic characteristics, resulting in a single bandpass filter. In turn, spiral resonators were attached to the microstrip transmission line at the gaps in the transmission line to obtain a compact dual passband filter. Stepped impedance microstrip line and Tshaped stubs were attached to the microstrip line in between spiral resonators. The structure designed resulted in a Triple bandpass filter. A fractional bandwidth of 3% was achieved at the center frequency of 3GHz. The filter had a 1.5dB insertion loss which is the minimum value in the operating frequency band. The filter resonance frequency was 1.32 GHz and 2.47GHz which have a fractional bandwidth of 7.5% and 4.85% respectively and the corresponding insertion loss was 1.3dB and 1.8dB respectively. The triple bandpass filter had a fractional bandwidth of 1. 16%, 11.4%, and 1.86%, centered at 1.29 GHz, 2.27 GHz, and 3.21GHz with 1.6dB, 1.3dB, and 1.8 dB insertion loss at the respective frequencies. The proposed bandpass filters are useful for GPS, WLAN, WiMAX, and radar applications.