Near-field to near/far-field transformation for arbitrary near-field geometry utilizing an equivalent electric current and MoM
Near-field to near/far-field transformation for arbitrary near-field geometry utilizing an equivalent electric current and MoM
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DOI：
10.1109/8.768793
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发表时间：
1999-03
影响因子：
5.7
通讯作者：
T. Sarkar;A. Taaghol
中科院分区：
文献类型：
--
作者：
T. Sarkar;A. Taaghol
本文提出了一种计算天线近场和远场方向图的方法，该方法由任意形状的几何形状上的近场测量得到。该方法利用近场数据来确定环绕天线的虚拟表面上的等效电流源。一旦确定了这个电流，就可以用来确定近场和远场。这种方法证明了解析连续性的概念，即，一旦空间中一个区域的电场的值已知，从理论上看，它对任何其他区域的值都可以外推。结果表明，无论近场测量的几何形状如何，等效电流在天线前面的区域产生正确的场。在这种方法中，测量数据不需要满足奈奎斯特抽样标准。建立了电场积分方程式，将近场与等效电流联系起来。采用矩量法将积分方程组转化为矩阵方程进行求解。采用奇异值分解的最小二乘法求解矩阵方程。在不同几何表面上测量了几种天线配置的近场，用合成数据和实验数据的计算表明了该方法的准确性。
Presented here is a method for computing near- and far-field patterns of an antenna from its near-field measurements taken over an arbitrarily shaped geometry. This method utilizes near-field data to determine an equivalent electric current source over a fictitious surface which encompasses the antenna. This electric current, once determined, can be used to ascertain the near and the far field. This method demonstrates the concept of analytic continuity, i.e., once the value of the electric field is known for one region in space, from a theoretical perspective, its value for any other region can be extrapolated. It is shown that the equivalent electric current produces the correct fields in the regions in front of the antenna regardless of the geometry over which the near-field measurements are made. In this approach, the measured data need not satisfy the Nyquist sampling criteria. An electric field integral equation is developed to relate the near field to the equivalent electric current. A moment method procedure is employed to solve the integral equation by transforming it into a matrix equation. A least-squares solution via singular value decomposition is used to solve the matrix equation. Computations with both synthetic and experimental data, where the near field of several antenna configurations are measured over various geometrical surfaces, illustrate the accuracy of this method.