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I'm in my parking lot and just a little too far from my car for the remote to work... But if I hold the remote up to my chin, and then suddenly it works.
It sounds dumb until you try it, but it definitely works, with lots of different remotes/cars. I assume it has something to do with the capacitance of your head, but I don't understand the details.
This is just speculation. To confirm any of this would take some careful measurements with fairly sophisticated equipment.
Two things come to mind. First, just raising the remote should help with its range. Try holding it up at chin level but not near your head.
Second, it's possible that the length of your body is roughly resonant at the RF frequecy. By feeding the signal into your body antenna at one end and with the other end loosely coupled to ground your whole body might start acting like a antenna. With the transmitter at waiste level, your body antenna is center fed, which doesn't cause it to resonate as well. Again, this is all just speculation.
I posed this same question to my Electromagnetics professor. His said he would think your skull is acting as a directional reflector and thereby extending the range by focussing more energy to the vehicle.
Another explanation was posted by the New York Times:
The trick turns your head into an antenna, says Tim Pozar, a Silicon Valley radio engineer.
Mr. Pozar explains, “You are capacitively coupling the fob to your head. With all the fluids in your head it ends up being a nice conductor. Not a great one, but it works.” Using your head can extend the key’s wireless range by a few car lengths.
My guess is to agree with the human antenna comment. However, the fluids in your head don't jibe with the fact that it works even better if you press the remote on a nearby metal light pole, no head required.
It might be because of just the change of orientation of the antenna. You probably kept the orientation of key the same according to your hand for every experiment you did.
Here's the best explanation I've seen: https://www.youtube.com/watch?v=0Uqf71muwWc
My understanding is there are two frequencies involved. One is the frequency of the signal, and the other is the data rate which is much low.
When you push the button on the remote, it starts sending a bit, either a 1 or a 0. These might be different amplitude, frequency or phase, but in any case, the bit is held for a large number of periods of the signal. During that time, your head starts to oscillate as an antenna at about the same signal frequency. The car is far away, so it sees the remote and your head as reinforcing the same signal.
Eventually the bit changes, and after a few periods your head is now repeating the new signal.
Net effect, your head improves the remotes range.
