I mean, it's electromagnetic waves. The right wavelength will bounce off things and increase likelihood of receiving a coherent signal. Works for a lot of things; RF, sound, light. RF has low energy and huge wavelengths. IIRC keyfobs are in the 200-600MHz range.<p>Ha, found some (kind of) evidence:<p>Radiowave Effects on Humans - March 28, 1980 / T. Neil Davis (<a href="https://www.gi.alaska.edu/alaska-science-forum/radiowave-effects-humans" rel="nofollow">https://www.gi.alaska.edu/alaska-science-forum/radiowave-eff...</a>)<p><pre><code> One reason the question is unanswered is that the energy absorbed by a human from radio waves depends upon the relationship between the size of the human and the frequency of the radio waves. Just as a TV antenna of the right length and orientation picks up the best signal (the most energy) from a transmitted wave, so it is with a human being. It appears that the cranial cavity of a mammal will resonate at specific radio frequencies determined by the size of the brain cavity. At these resonant frequencies the human head will absorb vastly more radiowave energy than it will at other nearby frequencies.
An adult's head will resonate at a frequency between 350 and 400 MHz (megahertz). Being smaller, a child's head will resonate at a higher frequency, somewhere between 600 and 850 MHz. Since each individual may have his or her own resonant frequency, a particular frequency radiowave might affect one person more than another. Consequently, testing on humans--even if people are willing to let this happen--can be rather complicated.
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Basically the human head is a resonance chamber that probably amplifies the signal. But also your body is made of water, and RF bounces off metal and water. The capacitive coupling of skin probably adds an enhancement to the effect.