Novel half-patch based 1-D periodic structure with better control over stop bandwidth

In this paper, novel half-patch loaded microstrip line based 1-D periodic structure is discussed. An asymmetric patch once sandwiched between microstrip line and ground present Electromagnetic Bandgap (EBG) characteristics with better control over the stop bandwidth. The proposed arrangement consists of a patch with one end grounded through a via and with other end floating under the microstrip line. Dispersion analysis is carried out to investigate the first two propagating modes of the proposed structure and are compared with a conventional full-patch structures. The effect on stop bandwidth caused by the open end location of the patch is explored. A variation of 10% to 45% in the percentage stop bandwidth is observed by a mere change of patch floating end position under the microstrip line. One such configuration as half-patch structure along with its corresponding full-patch version was fabricated and measured in lab. The measurements show that half-patch structure exhibits 33.8% stop bandwidth when compared to conventional full-patch structure that presents 50% bandwidth. The proposed 1-D periodic structures can be used for narrow band applications that require excellent rejection characteristics with sharp roll off rates.