Effective wave number of composite materials with oriented randomly distributed inclusions

The design of composite materials with specific electromagnetic properties is important to applications in the aerospace, communications, defense, food, medical, power and transportation industries. In this paper, we follow the T-matrix method (P.C. Waterman, Proc. IEEE, vol. 53, no. 8, pp. 805-812, 1965; and Phys. Rev. D, vol. 3, no. 4, pp. 825-839, 1971), configurational averaging technique (L.L. Foldy, Phys. Rev., vol. 67, nos. 3 and 4, pp 107-119, 1945; M. Lax, Revs. Modern Phys., vol. 23, no. 4, pp. 287-310, 1951) and quasicrystalline approximation (TCQ) approach originated by Varadan et al (Phys. Rev. D, vol. 19, no. 8, pp. 2480-2489, 1979) to predict the effective wave number of composite materials with oriented randomly distributed inclusions. However, it is noted that the vector spherical wave functions translational addition theorems (VSWFTAT) used by Varadan et al were found to be incorrect (A. Qing, Proc. PIERS´03, 2003). Here, the corrected VSWFTAT are applied to formulate the problem. The problem of prediction of the effective wave number is cast as an optimisation problem. Due to the simplicity, versatility and strong search ability of the differential evolution strategy (DES) (Qing, IEEE Trans. Antennas Propagat., vol. 51, no. 5), the optimisation problem is solved using DES, instead of Muller´s method. Preliminary numerical results have been obtained.