Wifi Beamforming

Avery Pennarun's essay on Wi-Fi begins with a promise to cheat Shannon's Law and ends with a clear explanation of how beamforming, MIMO, and directional antennas do exactly that within the rules. The centerpiece is a live simulation where wavefronts add and cancel in real time.

Although the examples are radio signals, the same interference and phasing principles govern microphones, loudspeaker arrays, and the directional hearing of our own ears. It is a signal-processing exhibit disguised as a physics demo.