Electromagnetic fields in a spherical cavity embedded in a dissipative medium

Time-harmonic and transient electromagnetic fields in spherical cavities whose walls are made of any material characterized by (
\sigma, \mu, \epsilon
) are investigated. For time-harmonic fields the wave equation is solved exactly in both the cavity and wall regions when the excitation is an electric dipole located at the cavity center. Numerical information based on these exact solutions shows the influence of the wall parameters upon the fields and provides a basis for studying the applicability and validity of several often used approximations. From the time-harmonic solutions, the Laplace transforms of the field equations are determined. These transforms are very complex and therefore are inverted numerically. Numerical results describing the magnetic field due to a particular dipole current,
i_{d}(t)=(J - e^{-dt})
, are presented for several cases of interest.