机载大型相控阵EMC的双重区域分解方法

The electromagnetic compatibility (EMC) of large array antennas on airplane platforms is one of the difficult topics in eletromagnetic engineering. There are two challenges for sovling the problem: (1) array antennas are complex, and usually contain lots of composite metallic/dielectric materials and fine components; (2) airplane platforms are electrially very large. The method of moments (MoM) is one of the popular methods for accurate electromagnetic modeling. However, it is very high in computational complexity and storage, which prevents its application to solve engineering problems. Note that fast algorithms based on MoM usually suffer from a divergence issue and hybrid methods based on MoM result in loss of accuracy. Therefore, these methods derived from MoM are not able to fulfill a requirement for accurate modeling in cases such as low sidelobe and ultra-low sidelobe arrays. According to the geometric features and material attributes of airborne large phased arrays, the "dividing and ruling" policy will be adopted. Two types of MoM domain decomposition methods (DDM) based on the equivalence principle and macro basis functions will be studied, and breakthroughs will be made in them by taking "coupling" as the starting point. The mature theory of the double DDM will be established by combining the two types of DDM, and its massively parallel algorithm will be developed to overcome the computational complexity and stoge problem of MoM. The parallel double DDM will be employed to accurately simulate the EMC effects of airborne phased arrays, and the coupling mechanism between arrays and airplanes are revealed. Finally, the optimization solution to EMC problems of airborne arrays will be proposed.

机载大型阵列天线电磁兼容一直是电磁工程领域的难点课题之一。解决该难题主要面临两方面的挑战：(1)阵列天线结构复杂，通常包含大量金属介质混合材料和精细结构；(2)飞机电尺寸巨大。矩量法是广泛使用的精确电磁计算方法之一，然而其计算量和存储量都很大，无法解决目前面临的工程难题。值得指出，矩量法的快速算法通常不能收敛到可靠精度，矩量法的混合方法也会降低计算精度，二者都不能满足诸如低副瓣、超低副瓣阵列的精确仿真需求。 本课题根据机载大型阵列天线的几何特征和材料属性，采用"分而治之"的策略，研究基于等效原理和宏基函数的两类矩量法区域分解（DDM）方法，以子区域之间的"耦合"为切入点突破两类DDM的关键技术，建立完善的矩量法双重DDM理论，进一步开展大规模并行DDM研究，彻底解决矩量法的计算量和存储量问题，并将其用于精确仿真机载相控阵EMC问题，揭示阵列与飞机之间的耦合机理，提出机载阵列EMC优化方案。

机载大型天线阵列电磁兼容问题的难点在于天线阵列的结构复杂性和飞机的电大尺寸特性。研究了基于宏基函数和等效原理的两类矩量法区域分解方法（DDM）。研究发现，基于宏基函数的DDM与分块LU分解Right-Looking算法在数学上是等价的；在混合使用不同积分方程及不同基函数的情况下，基于等效原理的DDM仍然有效，并且揭示了迭代收敛性随着子区域间距、介质损耗的变化规律。根据机载天线阵列的几何特征和材料属性，将模型划分为天线和飞机两个子区域，通过在子区域之间和子区域内部分别使用基于等效原理和宏基函数的DDM，发挥了两类DDM的优势，建立了矩量法双重DDM。基于两类DDM算法特征，设计了高可扩展并行策略，大幅提高了算法计算能力，精确计算了某型飞机的天线性能与天线布局，计算结果与缩比模型测量结果一致。