Antenna in car is mainly used to get the magnetic energy of the radio waves and transfer it to the cars radio receiver. Antenna comes as a long and stiff wire (a kind of slim stick), they transmitts the radio signals into the space which works over the satellite. Without antenna in car, it is not possible to conncect radio. It is said as antenna should be placed higher as possible from the ground which is better to receiver the signal and transmit.
Antennas would be fixed in different places of vehicle like Mirror, Roof, Fender, Window, Rear screen, Trunk and Bumper. Probably in most of the cars like sedan and in hatchbacks, antennas are placed over the roof as it is high from the ground level. Due to advancement in technology, there are varieties of antennas available some of them are: Monopole Antenna, Patch Antenna, On-glass Antenna, Glued Foil Antenna and Fractal Antenna.