Figure 1
From: Far-field subwavelength imaging with near-field resonant metalens scanning at microwave frequencies

The SRR cell with a switch.
(a) Structure of the SRR with a resonant frequency of 3.55 GHz. (b) The four statuses of the switchable SRR. When the subwavelength source is within the coupling scope of the on-SRR, the SRR will transmit the subwavelength information to the far field via localized mode resonance at 3.55 GHz. The off-SRR cannot achieve the effective evanescent-propagating conversion.