Higher Order Statistical Characterization of Received Power Fluctuations for Partially Coherent Random Fields

We calculate and investigate the first four moments of the power received by a short dipole antenna placed inside a reverberation chamber. The analysis is based on the vector angular spectral representation of an idealized electromagnetic random field. It is found that truncating the higher order moments (in particular, the first two invariants) of the replica pairs, considered as an incoherent part, causes a deviation from the ideal negative exponential probability distribution, which is instead found to be a leptokurtic Pearson type-IV distribution with increased skewness. This results in a model of partially coherent random fields received by a real antenna. Using a generalization of Tai´s theory, it is demonstrated that the effective aperture of the antenna does not exhibit fluctuations. Implications for the uncertainty and distribution function of the Q -factor of the cavity are analyzed and discussed.