Electromagnetic wave scattering by quasi-homogeneous obstacles

In this work we investigate the electromagnetic wave scattering phenomena by quasi-homogeneous obstacles, namely obstacles with wavenumber functions not exhibiting large variations from an average value $\bar k$. First, we express the field coefficients by means of a T-matrix method for the corresponding piecewise-homogeneous scatterer and then perform the best linear approximation by differentials to express these coefficients as linear combinations of the distances of the wavenumber samples from k. Moreover, the total far-field pattern of the quasi-homogeneous scatterer is decomposed into that of the respective homogeneous scatterer with wavenumber k plus the perturbation far-field pattern, depending exclusively on the wavenumber's deviations from k. Numerical results are presented concerning (i) the far-field patterns, computed by the proposed technique and the T-matrix method, (ii) the variations of the perturbation far-field pattern, and (iii) the prediction of each layer's contribution to the far-field.