In rural and suburban areas, mobile operators typically deploy fewer base stations. Terrain features such as hills and trees can cause significant signal attenuation, and the vehicle body itself can further attenuate the base-station signal by about 15–20 dB. When a vehicle is travelling in such areas and the received signal level inside the car falls below −105 dBm, mobile phones may not work reliably. Installing an in-vehicle signal booster can greatly improve in-car coverage in areas with weak but existing base-station signals (however, if there is no network signal at all, the booster cannot restore coverage).

The main unit of the vehicle booster is usually mounted under the passenger seat. A magnetic-mount omnidirectional antenna is installed on the metal roof of the vehicle and used as the donor (receiving) antenna. The coaxial cable from the donor antenna is routed through the door-frame weather strip into the vehicle and connected to the BTS port of the vehicle booster.

A small patch antenna with a self-adhesive backing is installed at an appropriate location inside the vehicle as the service (coverage) antenna. The booster is powered from the vehicle’s 12 V supply, significantly improving signal strength and call quality inside the car.