Over what range of frequencies are the FCC human body RF exposure limits most restrictive?
Why The FCC's maximum permissible exposure (MPE) tables in OET Bulletin 65 dip to their lowest values in the VHF range because the human body is roughly resonant at those wavelengths. An adult standing on ground acts like a quarter-wave or half-wave antenna near 35 to 70 MHz, so it absorbs RF energy most efficiently there. In the 30 to 300 MHz band the uncontrolled-environment limit is 0.2 mW/cm2 (1.0 mW/cm2 controlled), the tightest numbers in the whole table.
Watch out The 300 to 3000 MHz choice is tempting because microwave energy feels more dangerous, but at those frequencies the body is electrically large and absorption is more superficial, so the allowed power density rises with frequency rather than falling.
Body resonance is VHF: 30-300 MHz is where the limits are toughest. Think of a person as a 2 meter antenna.