In this paper, we present a new combined field integral equation (CFIE) formulation for the analysis of electromagnetic scattering from arbitrarily shaped three-dimensional perfectly conducting and piecewise homogeneous dielectric composite body. The conducting/dielectric structures are approximated by planar triangular patches, which have the ability to conform to any geometrical surface. The surface covering the conducting body is replaced by an equivalent surface electric current and the surface of the dielectric by equivalent electric and magnetic currents. The all equivalent currents are approximated in terms of RWG (Rao, Wilton, Glisson) functions. The objective of this paper is to illustrate that the CFIE is a valid methodology in removing defects, which occur at a frequency corresponding to an internal resonance of the structure. Numerical results are presented and compared with solutions obtained using other formulations.