It's measuring output of EM radiation at radio frequencies! EM radiation heats body tissues and causes heating in the body when EM radiation passes through the

It's measuring output of EM radiation at radio frequencies! EM radiation heats body tissues and causes heating in the body when EM radiation passes through the body tissues. Nobody cares about "heat dissipation" from the battery or CPU; if the phone gets too hot then you don't touch it. Rocket science.