Abstract: Abstract Implementing the electromagnetic scattering measurements for full-scale targets, requires large enough outdoor range or indoor compact range facilities with huge expenses and technique burdens.As a result, the needs for imaging and radar cross section (RCS) diagnostic of stealthy vehicles can't be satisfied by the existing far-field measurement facilities.For solving this problem, in this paper a near-field to far-field transformation technique was proposed based on the scatter distribution function concept.A 3-D scatter distribution function model was constructed, and the scattering fields were recorded in the near-field region, in a 3-D scanning manner.The spherical wave basis functions were expanded in the cylindrical Cartesian and spherical coordinates separately, for transforming the near-field data into far-field ones.By using 3-D inverse fast fourier transform (IFFT) and interpolation techniques, the images and scattering cross sections of the scattering targets can be reconstructed.Both simulation and measurement results were presented to validate the accuracy of the proposed method.