Bandgap determination of triangular lattice EBGs in the ground plane

The bandgap of triangular lattice electromagnetic bandgap structure (EBGs) in the ground plane has been determined. It has been observed that the bandgap location is shifted from the case of EBGs in the substrate. The 2-D EBGs in the ground plane has significantly higher value of a/λga/λg, where a   is the lattice constant and λgλg is the guided wavelength. Triangular lattice EBGs at Ka band are designed by etching circular cylindrical holes in the ground plane of GaAs substrate and all these EBGs exhibit bandgaps at a higher value of a/λga/λg ratios (approximately 0.653–0.72, depending on r/ar/a ratio) than conventional EBGs, which are formed by drilling air holes in the substrate. The maximum bandgap is observed for a/λga/λg equal to 0.653 for r/a=0.45r/a=0.45.