Figure 5. Far-field subwavelength imaging results, in which we emit the single broadband illumination using a horn antenna and receive the time-dependent scattered fields in the far-field region by the other single horn antenna.

(a) An N-shaped dielectric object located near the metasurface. (b) The imaging results using the traditional minimum-least square algorithm. Here, an imaging resolution around λ/5 has been achieved. In (c–e), the distance between the object and metasurface is 4 mm, 10 mm, and 20 mm, respectively. (f) The dependence of sensing capacity on the distance between target and metasurface is plotted. The imaging quality is monotonously decreased as the distance of the object away from metasurface grows up.