  We propose a novel characteristic basis function method for analyzing the
scattering by dielectric objects based on the
Poggio-Miller-Chang-Harrington-Wu-Tsai formulation. In the proposed method, the
electric and magnetic currents are orthogonalized with the help of the singular
value decomposition, and are used as dual basis functions in a way similar to
the RWG and BC basis functions. We show that the use of the Calder\'{o}n
multiplicative precondtioner together with the proposed method can prevent from
the poor convergence of the solution of the matrix equation in problems
involving dielectrics. We considered three different shapes of dielectric
scatterers for the purpose of validation. The numerical results agreed well
with those obtained by the conventional method of moments and the proposed
method was faster than the conventional method. These results indicate that the
proposed method is effective for scattering analysis of the dielectrics.
