(a) Photo of the experimental setup. The array of 10 * 10 SRR is printed onto Duroïd 500 which has a low loss tangent. A small loop (attached on a grey tube) is used as the near field probe to measure the impulse responses from the 8 Vivaldis antennas to every SRR of the array. This probe can be translated in the , , or directions. A multiplexer (grey cylinder) is used to switch between the Vivaldi antennas. It is linked to the first port of a network analyser, while the second is connected to the probe. (b) Field at the collapse time after TR calculated using the set of impulse response for a passive TR focusing on the SRR (3,7), two units stand for one period of the array. Clearly, the focal spot is one period wide, that is, λ/18, deeply subwavelength.