Application of the measured equation of invariance to electromagnetic scattering by penetrable bodies

The measured equation of invariance (MEI) concept for the numerical solution of time-harmonic electromagnetic wave scattering by perfectly conducting bodies in unbounded regions is extended to handle 2-D penetrable scatterers. The MEI is essentially a numerically derived discrete equation which is satisfied by the fields scattered by a specific scatterer independently of the excitation. It is demonstrated that the development of an MEI for penetrable scatterers is as straightforward as for the case of perfectly conducting ones, and can be used as an accurate localized truncation condition in conjunction with finite-element/finite-difference grids that conform to the scatterer and extend only a few cells away from its boundary