A Compact Wideband Bandpass Filter Based On Folded High – Low Impedance Resonator

Abstract

A novel wideband bandpass filter with sharp roll off using folded high – low impedance resonator with aperture based edge coupled technique is presented. The proposed bandpass filter has a 3 dB fractional bandwidth of 101.8% and the structure is compact. The centre frequency of the filter is 5.5 GHz. The prototype filter is designed using a low cost FR4 glass epoxy substrate with a dielectric constant 4.4 and a thickness of 0.8mm. IE3D software is used for the simulation and optimization of the filter structure. Sharp roll-off of the filter structure is achieved by the two transmission zeros generated by the centrally loaded folded high - low impedance resonator. Stopband performance with 17.23 dB suppression level is obtained upto 13.6 GHz.