A router is a radio. At 2.4 GHz each wave is 12.5 cm from crest to crest; at 5 GHz about 6 cm. What you see on the floor is the computed field, its crests marching outward — slowed about five billion times — then bouncing off the concrete and crossing back through itself.
- FACT λ = c / f: 299,792,458 m/s ÷ 2.437 GHz = 12.3 cm; ÷ 5.21 GHz = 5.75 cm.
- MODEL 2D ray model (image method): direct path plus every 1st- and 2nd-order reflection off the outer concrete walls — 13 paths, summed with their phases. Drawn on the floor; computed in the router's horizontal plane.
- ILLUSTRATION The shells round the router are real wavelengths, drawn to a metre. Real time would be 2.4 billion crests a second.
Drag the router. Pinch or scroll to zoom out over the whole flat.