Does a WiFi client vary the strength of the signal it emits?
Solution 1:
First your wireless router in a metal container will NOT be compensated by the Wireless card. That will not happen.
Second, there are competing articles, but one common thread is that radiation must be of the ionizing kind to be a health risk.
5 GHz Wireless is not ionizing radiation and is generally considered to be safe.
Wireless radiation
Radiation that actually causes issues, could potentially cause cancer, etc., is usually ionizing radiation. It has a very high frequency and can cause mutations in DNA, possibly leading to cancer (more info on that process). The frequency required to be ionizing? At least 1,000,000 GHz. That is literally a 500,000 times higher frequency than what Wi-Fi transmits on, 2.4 GHz or 5 GHz. Non-ionizing radiation, which Wi-Fi falls under, does little more than transfer heat.
Lots of people use 5 GHz wireless, and I think we would know about it in the senior news magazines if radiation from wireless were harmful.