Fast calculation of RCS over a broad frequency band using FDM and AWE technique

Abstract

The fast dipole method (FDM) in conjunction with the asymptotic waveform evaluation (AWE) technique is presented for fast calculation of radar cross section (RCS) from arbitrarily shaped perfect electric conductor targets over a broad frequency band. The FDM, which is based on the equivalent dipole-moment (EDM) method, is employed to reduce impedance matrix storage and accelerate the matrix-vector multiplications in the solutions of the Taylor coefficients. The application of AWE technique enables fast frequency sweep analysis. The numerical results show that this method greatly increased the computational efficiency without losing accuracy conditions compared with the traditional method of moments (MoM) combined with AWE technique. Keywords-Fast dipole method, equivalent dipole-moment, asymptotic waveform evaluation, radar cross section, method of moments I. INTRODUCTIONPredicting the wide-band radar cross section (RCS) of the target has important real life significance, such as synthetic aperture radar imaging and anti-stealth technology. Both of them need the information of wide-band RCS. With the rapid development of computer technology, the method of moments (MoM) [1] for solving the surface integral equation (SIE) has become one of the important method to accurately estimate the target RCS. In order to obtain the RCS over a band of frequencies using MoM, one has to repeat the calculations at each frequency over the band of interest, which will spend a lot of computing time. In order to improve computational efficiency, the model-based parameter estimation [2], the best uniform approximation [3], the asymptotic waveform evaluation (AWE) [4], [5] technique and other methods have been developed in recent years.In the above approach, the AWE technique is widely used in the applications of electromagnetic scattering problems due to its easiness to combine with MoM, but restricted to the computer resource, it can not be used to solve the scattering properties of the electrically large target. Since the 1990s, some fast algorithms such as the FMM [6], MLFMM [7], CBFM [8] have been proposed and rapidly applied. Although these methods can effectively improve the computational efficiency and reduce memory requirements at the singlefrequency point, but the pointwise solution of broadband still -

Solutions of Broadband RCS Using AWE Technique and Equivalent Dipole Moment Method

“…The obtained electric current distribution is used to compute the scattered field and the radar cross section. The th q derivative of impedance matrix elements is [9]:…”

“…In the above approach, the AWE technique is widely used in the applications of electromagnetic scattering problems [8][9][10], it can not be used to solve the scattering properties of the electrically large target for the consuming time of calculating the impedance matrix is large. Recently, a technology that called equivalent dipole moment method (EDMM) is proposed in [11] changes this situation, it can accelerate the process of filling the impedance matrix and more derivative matrices.…”