Ideal boundary and generalised soft and hard conditions

Ideal boundary conditions require vanishing of the normal component of the complex Poynting vector at the boundary surface. A novel set of ideal generalised soft-and-hard-surface (GSHS) conditions is introduced which depends on a complex vector. GSHS conditions reduce to those of the SHS (soft-and-hard-surface) boundary when the complex vector becomes real valued. Basic properties for a plane wave reflecting from a GSHS plane are derived. It is shown that TE and TM components (with respect to the complex vector and its complex conjugate) of a plane wave are reflected from the GSHS plane as from respective perfect magnetic or electric conductor planes. Image theory for the GSHS plane is given with an example. Finally, realisation of the GSHS plane and its application in polarisation transformation are discussed.