The only difference that I know of between kitchen microwaves and WiFi signals is how much power is pumped through them.
Why is it that WiFi signals, being 1000 times weaker can travel so much further, while something like a concrete block can absorb $1000 \, \mathrm{W}$ of microwaves from a kitchen magnetron being blasted at it? Or am I mistaken about the materials that WiFi signals can pass through?
Best Answer
The big difference is that you want to cook with microwave ovens and to communicate with WiFi. Microwave ovens are allowed to leak up to 5 mW/cm^2 measured two inches away per the FDA standard. For WiFi he EU allows 100 mW EIRP, which is less than the oven could leak if it leaked evenly in all directions. Communication devices are built to work over a wide range of signal levels, so even if there is attenuation going through the walls you still get WiFi. The oven leakage is attenuated just the same, but we don't pay attention to it. The power level is far too low to cook with.