Abstract: Amplitude-phase detached interpolation technique is introduced to analyze broadband electromagnetic characteristics of complex targets in half space. The main phase factor is extracted and separately considered, while the remain term which broadband characteristics can be computed by the best uniform approximation since it varies smoothly with the change of frequency. Then the half-space Green's function is combined to calculate the electric vector, magnetic vector and scalar potential function respectively, thus obtain the scattering fields. Finally the wideband radar cross section (RCS) of the targets in half space at any frequency within the given frequency range can be obtained. The numerical results show that this method is efficient and accurate.