[dragontamer]

Water molecules block 2.4Ghz spectrum that WiFi uses.

This is on purpose: the idea is to make the common WiFi (and Bluetooth) bands short range on purpose, so that many people within a city block can have local WiFi or local Bluetooth without interfering with each other.

So 2.4GHz over a long distance kinda goes against the design of WiFi / Bluetooth.

[ac29]

> Water molecules block 2.4Ghz spectrum that WiFi uses.

This isnt really true to any significant degree that matters, unless you are literally under water.

Rain fade is a thing, but is really only meaningful above 10GHz.

edit: I should note, its not that water droplets dont attenuate radio signals, its just that losses on a typical radio path are already huge in perfectly clear weather - you might lose 99.99999999% (100dB) or more of your signal strength between transmitter and receiver anyways.

[bonzini]

The idea really was that 2.4GHz spectrum was already polluted by microwave ovens (because microwave ovens operate at the resonance frequency of water molecules), so it was left for public use.

[jwilk]

That's a common misconception:

https://www.wtamu.edu/~cbaird/sq/2014/10/15/why-are-the-micr...

> The microwaves in a microwave oven are not tuned to a resonant frequency of water. […]

> They heat the food through simple dielectric heating. […] Many types of molecules in the food absorb energy from the microwaves in this way, and not just water molecules.

[Johnythree]

2.4Ghz was a ISM junk band long before domestic microwave ovens arrived. In fact 2.4Ghz was used for microwave ovens specifically because it was an ISM band, and therefore was available.

[sandworm101]

Almost. 2.4GHz had been set aside for consumer devices long before wifi. Microwaves are essentially very powerful unlicensed transmitters. Wifi devices are also all unlicensed transmitters. So 2.4GHz devices don't use the same space despite microwaves, they use it because that space had already been given over to unlicensed devices. If not for microwave ovens we might not have wifi as it is today.

Back when people were gobbling up the spectrum, the military didn't care about 2.4GHz because of the water absorption issues. It wasn't good for communication at long distances and so it was allowed for consumer devices.