Two lanterns on a distant shore at night merge into a single blob of light. Likewise, a conventional flat antenna cannot tell apart two radio transmitters placed too close together: their signals mix, and the receiver sees only a jumbled mess. Engineers found a way out: they made the antenna not flat but like a stack of transparent plates. Each plate is a metasurface, a thin patterned sheet that slightly delays and twists the wave passing through it. When a wave from a transmitter passes through the entire stack, each plate leaves its own imprint, and from these imprints one can deduce exactly where the signal came from.

Such a layered antenna works like an interpreter who hears not just words but also intonation, pauses, and accent. Even if ten people speak at once, they can tell the voices apart. In experiments at frequencies from 36 to 41 gigahertz (the range for future 6G communications), an antenna made of several plates managed to separate signals from ten transmitters operating in the same beam. It not only found their directions but also suppressed interfering signals by a factor of 100—as if the noise of a crowd suddenly became quieter than a whisper.

Processing speed also improved. Previously, the system needed time to scan through possible directions, like a person searching for a familiar face in a crowd, shifting gaze from one to another. The new antenna does this instantly because each plate already 'remembers' its piece of the answer. As a result, latency dropped by a factor of 1000, and channel capacity increased by 13.5 times. For future 6G networks and radars, this means that in a crowded spectrum, you can hear everyone without raising your voice.

The stack of plates is like a layered cake, where each layer adds its own flavor. By combining all layers, the chef gets a dish that cannot be made from a single sponge. Similarly, a volumetric antenna sees what a flat one cannot. Two lanterns on the shore no longer merge — now each is visible.