Passive microwave imaging of incoherent sources is often approached in a lensless configuration through array-based interferometric processing. We present an alternative route in the form of a coded aperture realized using a dynamic metasurface. We demonstrate that this device can achieve an estimate of the spectral source distribution from a series of single-port spectral magnitude measurements and complex characterization of the modulation patterns. The image estimation problem is formulated in this case as compressive inversion of a set of standard linear matrix equations. In addition, we demonstrate that a dispersive metasurface design can achieve spectral encoding directly, offering the potential for spectral imaging from frequency-integrated, multiplexed measurements. The microwave dynamic metasurface aperture as an encoding structure is shown to comprise a substantially simplified hardware architecture than that employed in common passive microwave imaging systems. Our proposed technique can facilitate large scale microwave imaging applications that exploit pervasive ambient sources, while similar principles can readily be applied at terahertz, infrared, and optical frequencies.

中文翻译：

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具有动态超表面孔径的无源微波光谱成像

非相干源的无源微波成像通常通过基于阵列的干涉测量处理以无透镜配置进行。我们以使用动态超表面实现的编码孔径的形式提出了替代路线。我们证明该设备可以通过一系列单端口频谱幅度测量和调制模式的复杂表征来实现频谱源分布的估计。在这种情况下，将图像估计问题表述为一组标准线性矩阵方程的压缩反演。此外，我们证明了色散超表面设计可以直接实现频谱编码，从而为通过频率积分，多路复用测量进行频谱成像提供了潜力。示出了作为编码结构的微波动态超表面孔径包括比在普通无源微波成像系统中所采用的基本上简化的硬件架构。我们提出的技术可以促进大规模微波成像应用的发展，这些应用可以利用无处不在的环境源，而相似的原理可以很容易地应用于太赫兹，红外和光学频率。