Phase information and spatially coherent illumination have usually been considered indispensable components of most microwave imaging systems. Dynamic metasurface apertures (DMAs)—with their ability to generate spatially incoherent illumination—have recently supplanted these assumptions in favor of simplified imaging hardware. In light of this development, we investigate the coherence of a phaseless imaging system based on metasurface apertures. In doing so, we propose and experimentally demonstrate coherent and incoherent computational microwave ghost imaging using DMAs. These apertures can generate a multitude of distinct speckle fields at a single frequency by modulating the electrical properties of radiating complementary metamaterial elements patterned into the surface of a waveguide. We show that a pair of dynamic apertures, one acting as transmit and the other as receive, can achieve two-dimensional, phaseless, coherent imaging. Further, by averaging the intensity measurements obtained in this manner over a random set or ensemble of receive aperture distributions, we demonstrate that an incoherent imaging system can be achieved in which single-port ensemble averaging by the electrically large DMA plays the role of spatial averaging in a bucket detector. We investigate the effects of these different imaging schemes on the resulting reconstructions and provide experimental demonstrations.

中文翻译：

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具有动态超表面孔径的无相干相干和非相干微波幻影成像

通常认为相位信息和空间相干照明是大多数微波成像系统必不可少的组件。动态超表面孔（DMA）具有产生空间不连贯照明的能力，最近已经取代了这些假设，转而使用简化的成像硬件。根据这一发展，我们研究了基于超表面孔径的无相成像系统的相干性。在此过程中，我们提出并通过实验证明了使用DMA的相干和非相干计算微波幻影成像。这些孔可以通过调制辐射到波导表面的互补超材料元素的电学特性，在单个频率上产生大量不同的散斑场。我们展示了一对动态光圈，一个充当发射器，另一个充当接收器，可以实现二维，无相位，相干成像。此外，通过在随机集或在接收孔径分布的整体中，我们证明了可以实现不相干的成像系统，在该系统中，通过电大DMA进行的单端口整体平均在桶形检测器中起空间平均的作用。我们调查了这些不同的成像方案对所产生的重建的影响，并提供了实验证明。