Bandstop filter using hybrid EBG structure

A hybrid EBG structure is realized by etching rectangular slots and circular patterns in the ground plane of the microstrip line. A method is proposed by which the ripples in the passband of the rectangular slots are minimized, without degradation of the stopband rejection, by introducing a circular pattern between the rectangular slots. This novel hybrid EBG structure has been designed, fabricated and measured in order to verify the present approach. The simulated and measured results of this hybrid EBG structure have good agreement.