Invisibility of Triangular Anti-Isorefractive DNG Prisms Illuminated by Multiple Incident Plane Waves

The two-dimensional boundary-value problem of scattering by structures containing sharp edges allows for an exact geometrical optics (GO) solution only in particular cases, which usually involve restrictions on one or more of the following parameters: the number of plane incident waves; their polarization, phase and direction of incidence; the relationships between wavelength and dimensions of the scattering object; the electromagnetic properties of the scattering materials. An exact GO solution under incidence by a single plane wave is not known and presumably is not possible for wedge structures made of perfect electric or perfect magnetic materials [1], [2]. For penetrable wedges, the only known exact GO solution for a single wedge under incidence by a single plane wave is the scattering by a right-angle wedge made of anti-isorefractive DNG metamaterial [3]. The result obtained in [3] has been applied to obtain the exact GO scattering of two plane waves propagating in opposite directions by a DNG prism of rectangular cross section [4].