ANALYTICAL CALCULATION OF THE CONDUCTIVITY OF HIGHLY HETEROGENEOUS MEDIA WITH ALLOWANCE FOR PERCOLATION PHENOMENA A. M. Mandel' UDC 536 Purely analytical methods without employing any computer-empirical relations or parameters have been used to construct a simple model of the conductivity of a two-phase heterogeneous medium composed of grains in the form of oriented ellipsoids. The model is applicable at any, up to infinite, contrast of the conductivities of the phases and in the entire range of their possible concentrations. Moreover, it "automatically" predicts the existence of a percolation threshold, the value of which depends on the grain shape. JEPTER7492019992 JEPTER749202