基于Fourier-MLP的双连续介质粒子建模及不变嵌入T矩阵加速计算方法

Fourier-MLP-Based Implicit Modeling of Continuous Medium Particles for Efficient Scattering Simulation with the IITM Method

  • 摘要: 大气粒子在微波及毫米波频段下的电磁散射特性对雷达系统性能评估、降水相态识别以及电磁传播建模具有重要影响。传统散射建模通常将粒子视为均匀介质结构,但此类近似难以刻画其真实的非均匀内部特性。尤其当粒子尺寸与入射波长相当时,该简化处理易引入较大的建模偏差。为提高散射模拟的物理逼真度,本文采用连续介质近似(Continuous Medium Approximation, CMA)描述粒子内部介电分布,并结合不变嵌入 T 矩阵方法(Invariant Imbedding T-Matrix, IITM)开展高精度散射特性计算。IITM 方法作为近年来发展迅速的电磁计算技术,具有较好的数值稳定性和广泛适用性,特别适用于结构复杂、介质分布非均匀的散射体建模。然而,在处理连续介质分布时,该方法仍需依赖高分辨率三维体素划分,并受限于频繁的坐标转换与介电参数检索,计算效率难以进一步提升。针对上述问题,本文构建了一种基于 Fourier 特征编码的多层感知网络(Fourier-MLP)隐式建模框架。该方法以三维空间坐标为输入,可快速预测局域介电特性,从而实现粒子内部结构向 IITM 计算域的高效映射。实验结果表明,所提出的 Fourier-MLP 框架在保持物理一致性的前提下,显著降低了散射计算的时间成本,并在粒子结构重建精度与散射响应一致性方面均表现出优异性能。

     

    Abstract: The electromagnetic scattering characteristics of atmospheric particles in the microwave and millimeter-wave frequency bands have a significant impact on radar system performance, precipitation identification, and propagation modeling. Traditional modeling methods often simplify particles as homogeneous structures, which fail to accurately capture their true inhomogeneous distributions, especially when the particle size is comparable to the wavelength. To improve modeling accuracy, this study adopts the Continuous Medium Approximation (CMA) to describe the internal structure of particles and employs the Invariant Imbedding T-Matrix (IITM) method for high-precision scattering calculations. As a recently developed electromagnetic computation technique, IITM offers broad applicability and good numerical stability, particularly suitable for modeling complex and inhomogeneous particles. However, when applied to continuous media, IITM still requires high-resolution 3D voxel discretization and suffers from frequent coordinate transformations and medium property lookups, resulting in high computational costs. To address this, a Fourier feature encoding multi-layer perceptron (Fourier-MLP) is proposed in this work to perform implicit modeling of binary continuous media structures. This method takes 3D spatial coordinates as input and rapidly predicts the corresponding medium properties, enabling efficient mapping between particle structure and the IITM computational domain. Experimental results demonstrate that the proposed method maintains physical consistency in modeling while significantly reducing the cost of scattering calculations, achieving high accuracy in both structural reconstruction and scattering response.

     

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