Chirp backscattering by pec sphere eccentrically placed in a dielectric sphere

A plane electromagnetic (em) wave, amplitude- and frequency-modulated as a linear chirp, is incident on a dielectric sphere that hosts an eccentric, spherical, pec (perfect electric conductor) inclusion. This radiation problem is solved in the frequency domain by use of symmetry-dependent, spherical eigenvectors, the end-result being a set of linear equations for the wave amplitudes of the frequency spectrum of the electric field in every part of space. That set is solved by truncation and matrix-inversion, separately for even- and odd-symmetry wave amplitudes. The backscattered chirp is found by an inverse Fourier transform that yields the time-dependent, monostatic, radar cross section (mrcs). A numerical application manifests the possibility to detect a pec sphere concealed in an acrylic sphere by use of a wide-band chirp that targets a morphology-dependent resonance (mdr) of the composite body. Our theory and code are validated by use of a commercial software. (C) 2020 Elsevier Ltd. All rights reserved.