why does holding your cellphone or key fob up to your head boost its signal ?
In: Physics
Apparently the radio waves pass through half your head and the opposite side becomes a parabolic reflector. Like a radar dish.
It doesn’t boost the signal, though it can make it work at a larger distance. The fob is omnidirectional, it sends radio in all directions. This is often very convenient, but it means that the available power drops at the fastest rate. If you hold the fob next to a radio reflector, you can get all the energy going in the same direction. If this isn’t pointed at your car it will make the range less, but if it is pointed at your car it will extend the range. It’s the same power, but in a tighter beam.
Alas, it’s inconvenient to walk around with a radio-reflective dish, just in case. Folks have found that the inside surface of your head is a not-very-good radio reflector, with the convenience that you’re already carrying it around with you all the time. It only has to be 10% efficient as a reflector to get you 10% more range, so the NVG problem isn’t large if you only need anther row of cars in the parking lot of range.
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