The evaluation of the electromagnetic field diffracted by a collection of similar metallic objects is obtained using theCharacteristic Modesfor the single scatterer as basis and weighting functions in the MoM solution of the whole scattering grid. Due to their resonant behaviour, only a few characteristic modes are required for an accurate representation of the current distribution even in presence of mutual coupling. Characteristic modes has been numerically evaluated for cylindrical scattered of different shapes and successfully applied to the computation of current density and scattered far field. Several numerical results are presented and computational advantages of. this approach over classical MoM are discussed.