Ultra wide-stopband planar microstrip bandpass filter above defected ground structure

Abstract

In this paper, the design of a compact planar bandpass filter above a defected ground plane is presented. The filter is designed as a combination of microstrip resonators and exploits the properties of a planar electromagnetic bandgap (EBG) structure patterned unto the ground plane of the printed circuit board material to provide a very wide stopband of up to 5 times the fundamental frequency. The structure is fabricated and excellent agreement between measurement and simulation results are obtained; attesting for the functionality of this design approach. The proposed filter herein features operation at the protected L-band radiometric region centered around 1413MHz.