Millimeter-Wave Imaging Using 1-Bit Programmable Metasurface: Simulation Model, Design, and Experiment

In this paper, a comprehensive study of millimeter-wave (mmW) imaging for far-field and near-field objects using 1-bit programmable metasurface (PMS) is presented. Theoretical PMS imaging simulation models are proposed by using plane-wave angular spectrum approach, in which two simulation models based on the flexible mmW beam-forming of PMS are developed. The first imaging model steers the high-gain beams electronically to scan over the region of interest, which is suitable for far-field object detection and surveillance. In the second model, randomly complex beams are generated that can sample the target objects in time domain, which is suitable for Fresnel region imaging. Physical optics theory is employed in the two imaging models for calculating reflected waves. Then, a 1-bit 20 x 20 PMS imager operating at 35 GHz is designed. The PMS imager is composed of a PIN-diode-loaded metasurface and a control board with 400 output channels. Finally, we measure 64 groups of randomly distributed fields using the planar near-field scanning technique in the anechoic chamber. Through imaging reconstruction, it is verified that the proposed PMS is a promising technique for mmW imaging with excellent performance.