Compact lowpass filter with wide stopband using novel windmill resonator

Abstract

A compact lowpass filter (LPF) with wide stopband using novel windmill resonators is presented. Compared to some other reported compact and wide LPFs, the LPF using the novel windmill resonator has great improvements on size reduction and stopband width, simultaneously, with a simple geometry. At the 3 dB cut-off frequency of 1.76 GHz, the designed LPF achieves a wide stopband with overall 20 dB attenuation to seven times the cut-off frequency. The compact dimension of this filter is as small as 0.19λg × 0.25λg, where λg is the guide wavelength at the cut-off frequency. The proposed filter is simulated, fabricated, and tested. Measured results show good agreement with simulated ones.

Acknowledgement

This work is supported by the Natural Science Foundation Project of CQ CSTC (CSTC2010BB2243), the Fundamental Research Funds for the Central Universities of CQU (CDJZR11160007, 1110611106).