The Transient Electromagnetic Response of a Spherical Shell of Arbitrary Thickness

Starting with the plane‐wave solution for scattering from a two‐layer sphere, the quasistatic response of a thin conducting shell is recovered analytically. Responses are also computed for shells of arbitrary thickness, and the range of validity of the thin‐shell approximation is determined. These results are extended to the time domain by a numerical inverse Fourier transform which yields the response to a step‐function incident field (magnetic or electric). It is found that under the thin‐shell approximation, the transient response has a simple single‐exponential form. This is modified to some extent when the arbitrary thickness of the shell is allowed for.