Vehicle Antenna mounting for two way radio communication should ideally be placed in the centre of a cars roof.
This is because for maximum efficiency of the antenna system it relies on what is known as a ‘ground plane’
The vehicles metal roof provides the ground plane, and forms part of the antenna.
Many taxi drivers seem to have them on the back boot lid of their cars. This is not ideal in terms of efficiency for a couple of reasons.
Firstly, what is known as the ‘reflected power’ can increase, leading to less transmission power going out, and some being reflected back into the equipment.
Secondly, the vehicles body which is higher than the boot that the antenna is mounted on, acts as a partial barrier to the signal in certain directions. This reduces both transmit and recieve performance range.