Why does cellphone signal go through buildings easily but basements are consistent dead spots?
In: Technology
Likely due to the materials used.
Timber frame and dry wall? It’s not dense enough to provide a significant obstacle to wave signals. Concrete blocks of a basement on the other hand are.
The walls are almost certainly reinforced concrete. The rebar (reinforcement) in the walls is steel, almost certainly spaced 12” on center or closer. Probably in two layers.
A cellphone signal also has a wavelength of about 12”
Waves can’t pass through an aperture smaller than the wavelength, they get massively disrupted by it. This is true for sound, water and electromagnetic waves. This is why microwaves don’t get out of your microwave and cook your face when you look in.
The general effect here is the rebar in the walls basically forms an almost-faraday cage, where the steel bars in the walls mostly stops the cellphone signals from getting in.
It’s not a perfect faraday cage, the crossing bars aren’t ideally connected and the spacing is borderline, and the lapping bars aren’t truly continuous – so some signal might get through, but generally you’re getting zero to terrible signal.
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