A MODIFIED MICROSTRIP-LINE TYPED PHOTONIC BAND-GAP (PBG) STRUCTURE THROUGH COMBINATION OF INDUCTIVE AND CAPACITIVE ELEMENTS FOR S-PARAMETER ENHANCEMENT

Microwave Photonic Bandgap (PBG) structures are conventionally realized by cascading periodic distributive elements. In microstrip-line circuits, such PBG properties can be obtained by placing periodic perforated holes on the ground plane along the direction of propagation. Nevertheless, the spectral properties may be improved by additionally introducing an inductive element in conjunction to the perforated holes on the PBG circuit. This inductive element is realized by tapering the main strip on the sections corresponding to the perforated holes. Through comparison of the scattering (S) parameters, the PBG structure with combined inductive and capacitive elements is superior to both with either purely inductive or capacitive elements.