We review the evolution of metasurface antennas for computational microwave imaging and highlight the advantages and disadvantages of various configurations. As an illustrative example, we examine a computational imaging system comprising dynamic printed metasurface cavities as modular building blocks. These metasurface cavities can generate a multitude of spatially diverse, voltage-controlled illumination patterns, and can therefore encode a scene’s reflectivity distribution into a set of measurements that can be postprocessed to produce an image. These single-port devices act as transmitters (Txs) and/or receivers (Rxs) and can be combined to create an electrically large aperture with a reduced number of (expensive and cumbersome) radio-frequency (RF) components. Here, we present some of the unique possibilities made possible by a dynamic metasurface imager. Specifically, we demonstrate high quality imaging with a reduced bandwidth of operation—as narrow as a single frequency. We then provide performance predictions for the case when dynamic metasurface cavities are used to image humans, as might be relevant in many security-screening applications. We conclude by describing the outlook of metasurfaces for imaging and identifying several future directions.

中文翻译：

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具有动态超表面的计算成像：简单且低成本的微波成像方法

我们回顾了用于计算微波成像的超表面天线的发展，并强调了各种配置的优缺点。作为一个说明性示例，我们检查了一个计算成像系统，该系统包括作为模块化构建块的动态打印超表面腔。这些超表面空腔可以生成多种空间多样化、电压控制的照明模式，因此可以将场景的反射率分布编码为一组测量值，这些测量值可以进行后处理以生成图像。这些单端口设备充当发射器 (Txs) 和/或接收器 (Rxs)，并且可以组合以创建具有减少数量（昂贵和笨重）射频 (RF) 组件的电大孔径。这里，我们展示了动态超表面成像仪带来的一些独特可能性。具体来说，我们展示了具有降低操作带宽的高质量成像 - 窄至单个频率。然后，我们针对使用动态超表面腔对人体进行成像的情况提供性能预测，这可能与许多安全筛选应用相关。最后，我们描述了用于成像的超表面的前景并确定了几个未来的方向。