Efficient EM Scattering Modeling from Metal Targets Coated with Anisotropic Thin Layers

Abstract

To address the challenges posed by composite targets composed of an anisotropic medium and metal in electromagnetic (EM) scattering calculations, this paper introduces an innovative hybrid algorithm tailored for simulating the EM scattering characteristics of such complex targets. Utilizing impedance boundary condition (IBC), the method employs surface impedance vectors to precisely depict the EM properties of the medium. By harnessing the distinct advantages of the Method of Moments (MoMs) at low frequency and Physical Optics (POs) at high frequency, the algorithm ensures both accuracy and efficiency in the EM simulation of composite targets. By transforming the EM scattering problem of targets coated with a thin-layered medium into an equivalent radiation problem of EM currents on impedance surfaces, this research has achieved rapid and high-precision calculations of the Radar Cross Section (RCS) for complex targets with anisotropic medium coatings. To assess the performance of the algorithm, three target models—square plates, simplified aircraft, and complex satellites—are selected as test cases. The dual metrics of RCS and surface current distribution are utilized as evaluation benchmarks, and comparisons are made against the Method of Moments–Finite Element Method (MoM-FEM) hybrid numerical method. The comparative results demonstrate that the proposed method meets the engineering standards in terms of both the root mean square error (RMSE) of RCS and the relative error in surface current distribution, while also achieving a significant improvement of over 50% in computational efficiency, thereby validating its superior accuracy and practical utility.

Efficient and Rapid Modeling of Radar Echo Responses for Complex Targets under Arbitrary Wideband Excitation

“…It can be observed that after the LFM signal undergoes matched filtering, its form changes from a wide pulse with a large time-bandwidth product to a narrow pulse. Additionally, the compression ratio r of LFM is equal to the product of the signal's timebandwidth product, as shown in Equation (13).…”

“…Moreover, inverse imaging algorithms for SAR based on time-domain stepped-frequency radar methods were introduced [8][9][10][11]; these involved replacing linear frequency-modulated pulse excitation with Gaussian pulses, demodulating scattering echo data, compressing pulses, and performing the azimuth inverse fast Fourier transform (IFFT) to obtain radar wideband echo signals. Additionally, a range of efficient EM scattering domain PO modeling methods were proposed for single/multi-layer anisotropic medium-coated metal conductor targets [12][13][14][15][16][17].…”

“…Secondly, although there have been advancements in target EM scattering simulation algorithms, they are limited to providing simulation data and do not meet the demand for various parts of scattering data and the underlying "information" required for target recognition [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Unfortunately, these critical pieces of information are often lost during the synthesis process, making it extremely challenging to extract target scattering characteristic information, particularly when dealing with the complex requirements of precise radar target recognition systems.…”