[mmaunder]

Not sure I agree with the cavity theory. I suspect it’s you, you big ole bag of salt water, acting as a capacitive ground plane for the antenna. It’s like mounting a ham or CB antenna on a car and having the metal of the car not be in direct contact with the ground, but it acts as a capacitive ground plane. You can do something similar with a vertical antenna using ground radials in a star pattern on the ground.

[Angostura]

If that were the case, wouldn't simply holding it in your ungloved hand be sufficient?

[teeray]

Probably not. Position of the antenna relative to the ground plane alters the radiation pattern. That’s why you’ll see police cruisers mount their antennas dead center on the roof—it creates an omnidirectional pattern. Mounting it to one side or another causes the field to radiate more in the direction with more roof in front of it (kind of the opposite of intuition). So the remote in your hand still likely interacts with your body, but not in a controlled or desirable way.

[gorlilla]

The ground plane is typically orthogonal to the antenna. Both TX and Rx antennae will have their own 'effevtive' ground plane relative to each other at any give point in time that will effect their Tx/Rx capabilities. Add into that, parking lots are full of metal objects and typically nearby large buildings. Those, also, will change the propagation characteristics of the general environment.

There's a lot at play in open-air environments. This does seem quite easy for DIY experiments using RTL-SDRs in varying environments.

[phendrenad2]

I think this is the real answer.