Improved S-approximation for dielectric particles A.Y. Perel'man State Forest Technical Academy, St.Petersburg, 194021 Russia and N.V. Voshchinnikov Astronomy Department and Sobolev Astronomical Institute, St.Petersburg University, St.Petersburg, 198504 Russia ABSTRACT The range of the applicability of the soft particles approximation (S-approximation) has been extended by means of the procedure which may be considered as a specific form of the analytic continuation. The initial element is represented by the standard version of the approximation while the branch of the continuation should be chosen in correspondence with the short wavelength asymptotic of the optical characteristic under consideration. As for the extinction efficiency of dielectric spherical particles, the improved version of the S-approximation fairly well describes the behaviour of Mie curves for particles with the refractive indices up to 2.0 or more and may be useful in order to get in the analytical form the "smoothed" Mie curves when the ripple-type fluctuations were averaged. The leading role of the van de Hulst approximation both for the electric and magnetic components of the extinction efficiency has been shown.