In a room with a dead corner, sound doesn’t travel. On the wall there’s a smart mirror: it catches the sound and re-reflects it, making the hidden audible. That’s how a reflective surface works in wireless communication. But if the source is right in front of you, the mirror only creates an echo. The new 'dormant mirror' technology solves this: its elements can change the arrival time of the wave and even its color. First, the surface sends a short test signal to gauge the brightness of the direct beam. If it’s strong, the mirror dims. If it’s weak, it activates and fine-tunes the reflection. This makes the connection crisp, without extra noise and with energy savings. Radio waves travel at enormous speed — every detail matters here. The most surprising part: in sleep mode, the mirror vanishes for radio waves, like an open window, leaving only a clean direct signal.
Prototypes of such surfaces date back to the 1960s — passive inflatable reflector spheres provided satellite communications without electronics, simply through their shape and metallic coating.