If you take the unit apart you will find the antenna is oriented lengthwise on the PC board. That means maximum radiation is at a right angle to the PC board. Point the remote at the car and it is in the minimum radiation pattern of the transmitter antenna. Point the remote at your chin and the receiver is now in the maximum radiation pattern of the transmitter antenna. The ‘chin’ had nothing other to do with this but to get you to ‘point’ the transmitter properly.
Best, Dan.