Sectoral band-gap of planar corrugated surfaces by asymptotic corrugations boundary conditions

Electromagnetic bandgap (EBG) surfaces have customarily been defined as being prohibitive of surface-waves within frequency ranges called bandgaps, for all directions along the surface, this latter specification being an understood presumed condition and thus left out. However, not all practical applications require such an entire bandgap in terms of surface directions. Rather, there could be some situations where surface-waves are required to be suppressed along directions only within an angular sector but are instead desired towards others outside. This work investigates this aspect using planar corrugated surfaces as the vehicle for study, in virtue of its ease of surface-wave modal analysis of dispersion by asymptotic corrugations boundary conditions (ACBC).