A PHASE MATRIX FOR A DENSE DISCRETE RANDOM MEDIUM - EVALUATION OF VOLUME SCATTERING COEFFICIENT

In the derivation of the conventional scattering phase matrix of a dis crete random medium, the far-field approximation is usually assumed, I n this paper, the phase matrix of a dense discrete random medium is de veloped by relaxing the far-field approximation and accounting for the effect of volume fraction and randomness properties characterized by the variance and correlation function of scatterer positions within th e medium, The final expression for the phase matrix differs from the c onventional one in two major aspects: there is an amplitude and a phas e correction, The concept used in the derivation is analogous to the a ntenna array theory, The phase matrix for a collection of scatterers i s found to be the Stokes matrix of the single scatterer multiplied by a dense medium phase correction factor, The close spacing amplitude co rrection appears inside the Stokes matrix. When the scatterers are unc orrelated, the phase correction factor approaches unity, The phase mat rix is used to calculate the volume scattering coefficients for a unit volume of spherical scatterers, and the results are compared with cal culations from other theories, numerical simulations, and laboratory m easurements, Results indicate that there should be a distinction betwe en physically dense medium and electrically dense medium.