Statistical modal analysis applied to near-field measurements of random emissions
Statistical modal analysis applied to near-field measurements of random emissions
复制标题
统计模态分析应用于随机发射的近场测量
DOI：
10.1109/tap.2002.807495
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发表时间：
2002
影响因子：
5.7
通讯作者：
F. Brouaye
中科院分区：
文献类型：
--
作者：
B. Fourestié;Z. Altman;J. Bolomey;J. Wiart;F. Brouaye
分析了窄带非相干电磁场的近远场转换问题。推导了在非相干源表面上时域采样信号的相干矩阵。介绍了基于相干矩阵处理的两种等价公式：信号子空间分析和双模态变换。在信号子空间方法中，相干矩阵使用基于奇异值分解的方法进行处理，从而在包围非相干源的表面上产生一组函数。这些函数中的每一个通过模态分解单独地变换到远场，并且变换函数的和给出总远场。在第二个公式中，使用双峰变换将近场相干矩阵变换为远场相干矩阵，从远场相干矩阵导出远场图案。在噪声的存在下，所提出的变换的应用程序进行了说明。一个数值例子使用非相干辐射偶极子内部泄漏线栅外壳验证了近场到远场变换的两个公式。所提出的方法给出了数学基础，设计一个紧凑的时域测量设备非常适合于非相干电磁辐射。
The problem of near-field to far-field transformation of narrow-band incoherent electromagnetic fields is analyzed. The coherence matrix of signals sampled in the time domain on a surface enclosing incoherent sources is derived. Two equivalent formulations based on the processing of the coherence matrix are introduced: The signal subspace analysis and the bimodal transformation. In the signal-subspace approach, the coherence matrix is processed using a method based on singular value decomposition, giving rise to a set of functions on the surface enclosing the incoherent sources. Each of these functions is individually transformed to the far field via a modal decomposition and the sum of the transformed functions gives the total far field. In the second formulation, the bimodal transformation is used to transform the near field coherence matrix into the far field coherence matrix from which the far-field pattern is derived. The applications of the proposed transformations in the presence of noise are illustrated. A numerical example using incoherent radiating dipoles inside a leaking wire-grid enclosure validates the two formulations of near-field to far-field transformation. The proposed methodology gives the mathematical foundation for designing a compact time domain measurement facility well suited to incoherent electromagnetic radiation.