Terrestrial Radio Antennas
Most cars ship from the factory with an antenna installed. This antenna is either a monopole whip antenna or a flat, window-mounted antenna. Whip antennas have been the standard for a long time, and come in several styles. Some whip antennas are rigid and stationary, others telescope out, and some retract and extend automatically when the radio is turned on and off.
Satellite Radio Antennas
Although terrestrial radio and satellite radio share a similar name, each requires different kinds of antennas. This is because terrestrial radio is broadcast from local towers on either the AM or FM band. Satellite radio is broadcast from a series of geosynchronous and geostationary satellites on a different wavelength. Unlike satellite television, which relies on directional dish antennas, satellite radio uses small, non-directional antennas. Satellite radio antennas are smaller than regular car radio antennas.
Television Antennas
Although analog VHF television and FM radio used to run parallel to each other (and overlap in some cases), the switchover to digital moved television broadcasts in the United States into the Ultra High Frequency (UHF) spectrum. In any case, you need a dedicated antenna to watch broadcast television in a car. There are a few kinds of TV antennas for a car, including the iconic boomerang antennas that are on limousines, and motorized satellite dishes that adjust automatically as the car moves. These are more useful in RVs, vans, and buses.
GPS Navigation Antennas
GPS navigation devices come with built-in antennas. Adding an external antenna increases the accuracy of these devices and reduces the likelihood of losing a satellite lock. Unlike other types of car antennas, which tend to be passive, GPS antennas can be either passive or active.
Cellphone Car Antennas
There are two types of cellphone car antennas:
Antennas that physically hook up to a cellphone.Signal boosters that amplify and retransmit weak cellular signals (like an active GPS antenna).
The former was more common. However, improvements in cellular technology have allowed antennas to be integrated into the design of phones, cars, and other receiver devices. Signal boosters, meanwhile, existed in a regulatory gray area until a 2013 FCC set guidelines for the use of these devices.
