The objective of this paper is to generate a wideband and temporal response from three-dimensional conducting structures. This is accomplished through the use of a hybrid method that involves generation of early time and low frequency information. These two are mutually complementary and contain all the necessary information for a sufficient record length. Utilizing orthogonal polynomials, time domain signal of scattering electromagnetic field could be expressed in an efficient way as well as the corresponding frequency domain responses. The available data is simultaneously extrapolated in both domains. Computational load for electromagnetic analysis, the Method of Moment (MOM), can be significantly reduced.