Fig. 1: Schematic representation and comparison of spatial and temporal aiming.
From: Temporal aiming
a–c Sketch of the conventional mechanical beam-steering technique, where the beam emitted by a source can be directed to either receiver 1 (Rx1) or receiver 2 (Rx2) by simply placing the source on a translation stage and moving it on the xz plane. d–f Temporal aiming sketch, considering a source emitting a monochromatic wavepacket embedded in a time-dependent medium, where its relative permittivity is changed from an isotropic value εr1 to a tensor \(\overline{\overline {\varepsilon _{r2}}}\)= [εr2x, εr2z] at t = t1. Vectors S and k are parallel before the change in εr for t < t1, d, and non-parallel for t > t1, e–f. The angle of the vector S can be designed to reach either e, receiver 2 or f, receiver 1, depending on the tensor \(\overline{\overline {\varepsilon _{r2}}}\) = [εr2x, εr2z]
