Measurement time-optimized calibration procedures for very large antenna arrays of millimeter-wave radars

几年来，在上毫米波范围内实现具有非常大的绝对测量带宽的角度生成雷达传感器也成为可能。传感器的阵列设计满足了更高角度分辨率和更大孔径的需求。这些阵列，其中一些有几百个波长的大小，很难用传统的校准方法进行校准，或者只能用极大的努力进行校准，因为校准必须以非常小的测量步骤进行。二维阵列通常不能作为角度的函数来校准。更复杂的是，各个部分或部分的关系。一个阵列可以在很大的绝对带宽上进行分辨，换句话说，该阵列的大小是几个距离分辨单元，因此在雷达操作中出现了角度和距离信息的耦合。因此，该项目的重点是研究毫米波和亚毫米波范围内非常大的电阵列的全新校准方法。为此，微波技术研究所（MWT）提出了一种利用阵列模态表示分析的新方法。与传统的校准方法相比，这种方法将天线的物理行为纳入校准。通过对物理天线行为的高效表示，新方法承诺基于很少的校准测量点进行校准，但可以深入了解使校准成为必要的作用机制。该方法将作为一种新的校准方法进行探索，该方法以计算量为代价显著减少了校准的测量工作量。此外，还将研究该方法的局限性，根据阵列进行校准需要哪些测量努力，以及使用该方法可以实现哪些校准质量。评估将在不同的演示器上进行，并将与传统校准方法进行比较。该项目的关键问题之一是使用紧凑的测量装置进行校准。因此，将研究如何使用近场测量数据进行校准。此外，还将研究使用部分次校准来合成完整校准数据集的概念。在次校准的帮助下，即使使用紧凑的测量装置，也可以在保持远场条件的同时校准非常大的电阵列。

For a few years it has also been possible to implement angle-generating radar sensors with very large absolute measurement bandwidths in the upper millimeter wave range. The array designs of the sensors meet the desire for ever higher angular resolutions with larger apertures. These arrays, some of which are several hundred wavelengths in size, are very difficult to calibrate with conventional calibration approaches or can only be calibrated with extreme effort, since the calibration has to be carried out with very small measuring steps. Two-dimensional arrays often cannot be calibrated as a function of the angle at all. A further complication is that the individual parts or section resp. of an array can be resolved over the large absolute bandwidths or in other words the array is several range resolution cells in size, and thus a coupling of the angle and distance information occurs in radar operation. Therefore, the focus of this project is the investigation of a fundamentally new calibration method for electrically very large arrays in the millimeter and sub-millimeter wave range. For this purpose, the Institute of Microwave Technology (MWT) proposes a new approach that uses an analysis of the modal representation of the arrays. In contrast to conventional calibration methods, this approach incorporates the physical behavior of the antennas into the calibration. Through a highly efficient representation of the physical antenna behavior, the new approach promises calibrations that are based on very few calibration measurement points and yet allow deep insights into the mechanisms of action that make calibration necessary in the first place. This approach will be explored as a novel calibration method that significantly reduces the measurement effort of calibration at the expense of computational effort. Furthermore, the limits of the method will be investigated, which measurement effort is necessary for the calibration depending on the array and which calibration quality can be achieved with it. The evaluation will be performed on different demonstrators and will lead to a comparison with conventional calibration approaches. One of the key issues of this project is the calibration with compact measurement setups. Therefore, it will be investigated how the calibration can be performed using measurement data from the near field. Furthermore, concepts for the use of partial subcalibrations to synthesize complete calibration data sets will be investigated. With the help of subcalibrations, electrically very large arrays are to be calibrated while maintaining the far-field condition, even with compact measurement setups.