Active Incoherent Millimeter-Wave (AIM) Imaging

近年来，毫米波技术在成像和遥感方面的应用显著扩大。由于毫米波天线和电子设备的小尺寸，再加上毫米波在雾、烟雾、服装和一些建筑材料中的传播能力，毫米波传感器在安全传感、医学成像、自动车辆传感和科学研究等领域正成为至关重要的工具。此外，毫米波成像能够在目前未得到充分利用的电磁体制下进行成像和传感，因此在上述领域变得越来越重要。尤其是天线阵列，因为它们比机械扫描的毫米波成像器更小的尺寸和更大的灵活性而变得更加令人感兴趣。该项目将开发一种新的毫米波阵列成像方法，称为主动非相干成像。提出的非相干成像方法有可能在不牺牲图像分辨率的情况下显著降低毫米波和亚毫米波成像的成本。此外，即使部分接收器阵列单元发生故障，所提出的方法的图像质量也不会显著下降，这提高了其相对于基于像素的成像方法的长期实用性。该项目的成果将使毫米波成像仪更容易为社会所接受，并易于在广泛的应用中实施。此外，这项研究的结果将用于加强密歇根州立大学现有的课程，并开发新的雷达和毫米波技术课程。结合稀疏阵列理论和空间频率采样，提出的有源非相干毫米波成像采用时空非相干发射机阵列和稀疏相干接收机阵列相结合的方法。虽然分辨率在许多应用中是毫米波成像的主要限制因素，但使用空间频率采样的稀疏接收器阵列可以被用来生成分辨率相当于具有至少一个数量级的少个数量级的元素的全填充阵列的图像。非相干成像的另一个好处是提高了效率，因为需要更少的接收器元件，并且非相干发射机阵列比相干发射机阵列更节能。该项目还将研究一种新的模块化封装格式，其中各个收发芯片被无线锁相，接收的数据被无线下行。这种分布式方法使新的成像方法可以直接扩展，并易于在未来的毫米波成像系统中实现。

The use of millimeter-wave technology for imaging and remote sensing has expanded significantly in recent years. Due to the small size of millimeter-wave antennas and electronics combined with the ability of millimeter-wave propagation through fog, smoke, clothing, and some building materials, millimeter-wave sensors are becoming critically important tools in areas such as security sensing, medical imaging, autonomous vehicle sensing, and scientific research. Millimeter-wave imaging furthermore enables imaging and sensing in an electromagnetic regime that is presently underutilized, and is thus becoming increasingly important in the areas stated above. Antenna arrays in particular are becoming of greater interest due to their smaller size and greater flexibility than mechanically-scanned millimeter-wave imagers. This project will develop a new method of millimeter-wave array imaging called active incoherent imaging. The proposed incoherent imaging approach has the potential to significantly reduce the cost of millimeter-wave and sub-millimeter-wave imaging without sacrificing image resolution. Furthermore, the image quality of the proposed approach does not degrade significantly even if part of the receiver array elements fail, which improves its long-term utility over pixel-based imaging methods. The results of this project will enable millimeter-wave imagers to become more accessible to society and to be easily implemented in a broad range of applications. Furthermore, the results of this research will be used to enhance existing courses and develop new courses in radar and millimeter-wave technology at Michigan State University. Combining aspects of sparse array theory and spatial frequency sampling, the proposed active incoherent millimeter-wave imaging utilizes a spatio-temporal incoherent transmitter array combined with a sparse, coherent receiver array. While resolution is the primary limiting factor in millimeter-wave imaging in many applications, sparse receiver arrays using spatial frequency sampling can be utilized to generate images with resolution equivalent to a fully filled array with at least an order of magnitude fewer elements. Incoherent imaging has the additional benefit of improved efficiency because fewer receiver elements are needed and incoherent transmitter arrays are more energy efficient to implement than coherent transmitter arrays. This project will also investigate a novel modular packaging format, where individual transceiver chips are wirelessly phase locked and the received data is wirelessly downlinked. This distributed approach enables the new imaging method to be directly scalable and easily implemented in future millimeter-wave imaging systems.