Size reduction of electromagnetic bandgap (EBG) structures with new geometries and materials

Size reduction of an electromagnetic bandgap (EBG) structure with large patches and small branches that connect adjacent patches for a power/ground plane pair is studied. To shrink the dimensions with a high isolation at the frequency of interest, this paper provides two approaches. One is a geometric approach which is to place two narrow slits on each patch. The increase of branch inductance with the long slit successfully decreases the on-set frequency of the stopband without increasing the patch size. The other approach is to use high-K material for a thin dielectric layer. In this case, the size reduction can be predicted according to a scaling law. These approaches are applied together to realize an EBG structure with the entire size of less than 20 mm on a side. It covers the GSM band with sufficient isolation. Through this study, the dispersion-diagram analysis is used to predict the stopband characteristics