Research On Interpolation Of Scattering From Complex Targets In A Broad Band

In the study of high range resolution, imaging technique and target recognition, fast and accurate computation of radar cross section over a broad frequency band is of great importance. However, for wide-band radar working at the wide range of frequency, to obtain the RCS over a broad-band, one has to repeat the calculation at a lot of frequency points over the band of interest, which will be computationally intensive. To overcome this difficulty, the approximate solution techniques that can efficiently simulate frequency response over a wide band with acceptable computational time are desired. Therefore, there is the important theoretical value and military applications as battlefield environment to carry out the study of broadband electromagnetic characteristics of complex targets.In this paper, the specific work and innovation include the following: 1. In order to obtain programming ability, method of moment (MOM), multiLevel mast multipole algorithm (MLFMA) and physical optics method(PO)are studied firstly, which is basis for interpolation methods. On this basis, the interpolation methods and numerical algorithm will be combined with calculation of broadband electromagnetic scattering characteristics of the target.2. Multilevel fast multipole algorithm (MLFMA) in conjugation with the best uniform approximation is applied to the scattering analysis of an arbitrary shaped perfect electric conductor over a wide frequency band .The nodes of Chebyshev within a given frequency range are found firstly , and the surface electric currents at these nodes are computed with MLFMA. The surface current on perfect electric conductor is expanded in a polynomial function via the best uniform approximation ,then the electric current distribution can be obtained at any frequency within the given frequency range , which is used to compute the scattered fields and the wide-band Radar Cross Section (RCS) . The results show that the computational efficiency is improved drastically without sacrificing much accuracy .3. Through the combination of the best uniform approximation with the extracted phase information of the surface electric currents on conducting objects, amplitude-phase detached interpolation method is introduced. Together with the conventional high-frequency method, the nodes of Chebyshev within a given frequency range were found firstly, and the surface electric currents at these nodes were computed. Then the electric current distribution, which is used to compute the scattered fields and the wideband radar cross section, can be obtained at any frequency within the given frequency range via amplitude-phase detached interpolation. The numerical results show that the proposed method is efficient and accurate.4. On the above basis, the best uniform approximation in conjugation with the phase extracted is applied to the high-frequency method in half space. Amplitude-phase detached interpolation technique is introduced to analyze broadband electromagnetic characteristics of complex targets in half space. The numerical results show that this method is efficient and accurate.