Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
That could be fixed by using WiFI calling, getting a VoIP line or installing a cell booster.
WiFi calling will make a direct beacon to follow, as any other WiFi use would. Faraday cages would block WiFi calling, as with any other signal.
I think these techniques can use the reflection of the signal from the AP’s own transmissions, no additional devices needed.
The Faraday cage will keep the WiFi signals inside the building. Nobody will be able to track you from outside and your own trusted devices will work fine inside. Just don’t bring any untrusted WiFi devices inside the Faraday cage.