I have just recently been getting interested in the whole EMF spectrum of late but something suddenly made me curious.
How strong does a radio frequency has to be in megahertz for you to feel it?
This wouldn't be a question of frequency, which isn't the "strength" of a signal - rather, the strength is the amplitude.*
To answer the question, it'd have to be in the dozens of watts for it to start to have an effect on the human body (think of a microwave oven, which operates at 700W+). WiFi is generally limited at a transmission rate of one watt, though it loses half its strength with every 3dB drop so by the time it gets to a device (or in this case a body) at highest it's at more like 0.0001W (1/10,000th of a Watt).
As a real-world example, I currently have a -68dB signal from my wireless AP to my phone, which equates to something like 0.00000015 mW (1/150,000th of a Watt), or enough energy to heat 1ml of water a tiny, tiny fraction of a degree.
That's just considering heat, though. In the case of electrosensitivity in humans, it's never been evidenced in any sort of blind or double-blind study, so as far as we can tell it doesn't exist but there's room for us to be wrong.
*Technically, frequency is also an important part i.e. gamma rays rather than Radio Frequency, but your question was specific about radio.
