I take it that electrodynamics wasn’t your best class in university.
Hint: all electromagnetic radiation – light, x-rays, cosmic microwave background, all of it – propagates until it runs into something after it gets out of the very close in “near field” radius. In that region, from a few wavelengths to infinity, the power density (watts per square meter) falls off inversely to the square of the distance from the source. This is as true for WiFi as it is for sunlight.
<headdesk> This is gibberish. “Amplitude” of an electromagnetic wave is the wattage. You can measure the power density (“Poynting vector”) or you can measure the individual electric and magnetic field strengths (volts/meter or tesla) but they all play together. The power is basically the product of the electric and magnetic field strengths, which are proportional to each other so that the power just varies as the square of either one – the relationship does not change with frequency (which is inversely proportional to wavelength; their product is the speed of light.)
