Electromagnetic reverberation near a perfectly conducting boundary

We analyze the effect of an infinite planar perfectly conducting surface on the physical and statistical properties of an otherwise ideal reverberant field. The surface induces statistical uniaxial field anisotropy at a distance, and its effect can be characterized based on calculable local field polarization and anisotropy coefficients that exhibit a damped oscillatory behavior as a function of the distance to the surface. It is shown, both theoretically and experimentally, that compound exponential (CE) distribution functions with a degenerate polarization coefficient as parameter govern the statistics of the local energy density and amplitude of the vector field near the surface. The influence of adjacent walls is taken into account by a transverse field anisotropy coefficient and gives rise to bifurcation of the polarization coefficient. The effect of the transverse field anisotropy on the statistics of the energy density, field amplitude, and their sample maxima as a function of distance to the surface is quantified. It is found that the increase in the expected value of the maximum electric field strength caused by the presence of the surface is of the order of 1 dB. Theoretical results are validated against measured data. A theoretical derivation based on a spectral plane-wave expansion for this configuration is given. The results are relevant to applications in which a sensor, test artefact or critical component in immunity testing is relatively close to a conducting surface, in aperture coupling between cavities, and in emissions measurement of total radiated power.