A more likely theory is that the fob transmitter (and antenna) is tuned to put out max signal when near the body. This is it's normal use. If however you tested it with the fob somewhat isolated it would then be out of tune. eg in the factory it would be tuned at a set distance from a "dummy body". It's the same with a walkie-talkie radio. The antenna must be tuned when held in the hand, as your body provides the mis…
The scenarios being compared are: - Fob in hand - Fob in hand, held against head Both of these already fulfill your “near body” requirement. Your point around tuning would not explain the specific difference being questioned.
I always did hold the fob close to my palm (with the keyring parts between my fingers) and pointing the fob "up", hopefully aligning a whip in there. It does work better this way, and I can also hold it high up. My theory was that my hand acts as a ground-plane.