Physical theory of diffraction for scatterers with low-reflection surface

The progress in the development of thin and lightweight artificial absorbers has revived interest in approaches to simulation of electromagnetic scattering from electrically large low-reflection bodies. The absorbers, irrespective of their interior structure, can be often adequately described by an equivalent surface impedance which is matched with the wave impedance of the surrounding medium. As full wave simulations of scattering from electrically large curved surfaces with underlying dense arrays of subwavelength inclusions are hardly possible, the main candidate is the physical theory of diffraction (PTD), adjusted to the use of impedance boundary conditions with the matched surface impedance. The paper describes a suitable PTD formulation with a focus on edge corrections.