A computational methodology which utilizes the transfer matrix method was modified to simulate the a.c. transport properties of two-dimensional composites of triangular network, a.c. impedance spectra of macroscopic mixtures of hard spheres which have the random arrangement or regular form cluster of components were studied. It was shown that the impedance spectra of the two-components composite might show three arcs. The third semicircle was shown to originate from the isolated clusters, and to appear more distinctively when the elongated clusters were arranged along the preferred current flow line. Finally, it was emphasized that the effects of geometrical arrangement must be seriously considered in the analysis of the electrical properties of composite, especially when the filling fraction of composites was near the effective percolation threshold.