Phaseless Inversion of Planar Magnetic Near-Field Antenna Measurements

位于卡尔加里的EMSCAN是一家世界领先的快速平面近场天线和 电磁兼容性测量技术。这个项目围绕着EMSCAN的RFxpert 提供近乎实时的天线测量的系统。RFxpert收集切向磁场 被测天线(AUT)在AUT近场区域的平面上的场。RFxpert系统是 能够收集这些磁场的幅度和相位。从这些测量来看，辐射 AUT的方向图可以使用标准的平面近场到远场变换来计算。 EMSCAN感兴趣的是研究从纯幅度(无相位)计算辐射方向图的方法 磁性近场数据。这一点很重要，原因有两个。首先，这可以显著减少 系统的成本，因为无相测量可以通过使用电源简单/准确地完成 仪表/嵌入式频谱分析仪。其次，这使EMSCAN能够估计 他们的EMC产品EMxpert只使用频谱分析仪来测量无相位磁场近场数据。 在拟议的项目中，Mojabi团队的目标是实现一种计算机算法，该算法采用无相位 在AUT前面的平面上收集的磁场近场数据，然后返回 奥特。为此，这个问题被表示为在上的非线性代价函数的最小化 AUT的等效电流。一旦找到AUT的等效电流，AUT的辐射方向图 天线可以很容易地计算。从无相相磁近场数据获得的辐射方向图将 然后与从幅度和相位磁场近场数据获得的辐射方向图进行比较，以 通过使用无相位数据来评估牺牲了多少精度。

EMSCAN, located in Calgary, is a world-leading developer of fast planar near-field antenna and electromagnetic compatibility measurement techniques. This project revolves around the EMSCAN's RFxpert system that provides almost real-time antenna measurements. The RFxpert collects the tangential magnetic fields of an antenna under test (AUT) on a plane in the near-field zone of the AUT. The RFxpert system is capable of collecting the amplitude and phase of these magnetic fields. From these measurements, the radiation pattern of the AUT can be calculated using the standard planar near-field to far-field transformation. EMSCAN is interested in investigating methods to calculate radiation patterns from amplitude-only (phaseless) magnetic near-field data. This is important for the following two reasons. First, this can significantly reduce the cost of the system as phaseless measurements can be simply/accurately done via the use of a power meter/embedded spectrum analyzer. Second, this enables EMSCAN to estimate electromagnetic emissions in their EMC product, EMxpert, that uses only a spectrum analyzer to measure phaseless magnetic near-field data. In the proposed project, the Mojabi team aims to implement a computer algorithm that takes the phaseless magnetic near-field data collected on a plane in front of the AUT, and then returns the radiation pattern of the AUT. To this end, this problem is formulated as the minimization of a nonlinear cost functional over the equivalent current of the AUT. Once equivalent current of the AUT is found, the radiation pattern of the antenna can be easily calculated. The radiation pattern obtained from phaseless magnetic near-field data will then be compared with the radiation pattern obtained from amplitude and phase magnetic near-field data to evaluate how much accuracy has been sacrificed by using phaseless data.