A novel photonic bandgap structure for low-pass filter of wide stopband

In this letter, a novel photonic bandgap (PBG) structure is proposed for increasing the stopband of a low-pass filter without the increasing circuit size for applications in microstrip circuits. The proposed structure is connected in two parallel periodic structures which have a different center frequency of the stopband. The wide stopband is achieved by two periodic structures of two different stopbands. We also show the performance improvement of microstrip patch antenna by etching of the proposed structure in ground plane.