Generalized, field-corrected antenna measurements (GFAM)

天线是导引波和自由空间波之间不可缺少的换能器。它们是每个高频无线系统的关键元素，无论是移动通信还是雷达传感器。利用第二天线作为测试天线，通过近场或远场测量，经验地获得了天线的辐射特性。然而，重要的是要确保测量结果独立于测试天线的辐射特性。在远场测量中，这是通过将天线放置在彼此的远场（R→∞）来实现的。在近场测量中，采用基于天线辐射方向图的解析测试天线校正。两种方法都假设了理想的环境和传播路径，没有反射和场相互作用。基于这些假设的试验区场分布仅近似于实际场分布，因此是测量误差的来源。用实测的测试区场代替解析推导的测试区场，克服了传统天线测量模型的局限性。测量的试验区场包括来自所有源的贡献，例如距离反射或泄漏。此外，实际对准和距离几何也被考虑在内。利用被测场进入测试区，引出了一种广义的场校正天线测量技术。天线的特性可以通过在任意但已知的测试区域的测量精确地确定。近场和远场天线测量的方法因此被结合在一个单一的理论。该项目的目的是全面发展和分析这种广义的、场校正的天线测量技术。该项目将球面扫描理论应用于测试区场测量，从而将其推广，以便天线测量可以用入射电磁测试区场的信息进行校正。测量实现的一个关键方面是精度。必须对该技术进行全面的灵敏度分析，以得出测试区现场扫描设置的要求。初步研究表明，定位误差和探针相关的影响是至关重要的。收集到的信息将用于构建优化的现场扫描设置。广义的场校正天线测量技术将进行广泛的测试，包括对测量数据的不确定度分析。由于全球面扫描所需的测量时间是一个缺点，因此将对测试区域场和天线测量进行不完全球面扫描可达到的精度进行研究。这种新方法有望开辟新的研究途径，具有大量可能的应用。例如，它将在测量系统的设计中提供无数的自由度，并将提高现有系统的测量精度。

Antennas are the indispensable transducers between guided and free-space waves. They are key elements for every high-frequency wireless system, be it mobile communications or radar sensors.The antenna radiation characteristic is obtained empirically by a near- or far-field measurement using a second antenna as test antenna. However, it is important to ensure that the measurement result is independent of the test antenna’s radiation characteristic. In far-field measurements this is achieved by placing the antennas in the far field (R→∞) of each other. In near-field measurements an analytical test antenna correction based on its radiation pattern is used. Both methods assume an ideal environment and propagation path without reflections and field interaction. The test zone field distribution based on these assumptions does only approximate the real field distribution and is, hence, a source of measurement error.Replacing the analytically derived test zone field by a measured test zone field overcomes limitations of the classical antenna measurement model. The measured test zone field encompasses the contributions from all sources such as range reflections or leakage. Furthermore, the actual alignment and range geometry is also taken into account. Using the measured field entering the test zone, leads to a generalized field-corrected antenna measurement technique. Antenna properties can be precisely determined from measurements in an arbitrary but known test zone field. The methods of near-field and far-field antenna measurements are thereby combined in a single theory.The objective of this project is to develop and analyze comprehensively this generalized, field-corrected antenna measurement technique.The project will apply the spherical scanning theory to the test zone field measurement and will thus in turn generalize it so that the antenna measurement can be corrected with information about the incoming electromagnetic test zone field. A critical aspect of the measurement realization is the accuracy. A comprehensive sensitivity analysis of the technique is mandatory to derive requirements for the test zone field scanning setup. Preliminary investigations have shown that positioning errors and probe related effects are crucial. The gathered information will be used to build an optimized field scanning setup. The generalized, field-corrected antenna measurement technique will be tested extensively including an uncertainty analysis with measured data. Since the required measurement time for full sphere scans is a disadvantage, the accuracy achievable with incomplete spherical scans will be investigated for both the test zone field and the antenna measurement.This new methodology is expected to open new research avenues with plethora of possible applications. It will, for example, provide uncountable many degrees of freedom in the design of measurement systems and will increase the measurement accuracy of existing systems.