An FM antenna is used to strengthen weak FM signal receptions or to get around strong ones. They use an arrangement of conductors that make electromagnetic fields in order to achieve these results. There are several styles of FM antennas, to include uni-directional dipole, turnstile, multi-element array and indoor FM antennas. The type of antenna one should purchase is determined by a couple of factors.
Uni-directional dipole antennas are recommended for areas where the radio stations are located in one general direction. They are most effective in rural areas directly outside of town, as the stations must be located within 20 miles (32.18 km) of the FM antenna to receive service. This antenna is large, so space must be taken into consideration. This antenna has two elements and more reception than the standard indoor dipole antenna.
The turnstile, also known as crossed dipole, FM antenna is a pair of dipole antennas that are positioned at right angles to each other. It resembles its name, in that when it lays in a horizontal position it looks like a turnstile. Because of the shape of this antenna, it doesn't need to be rotated to receive a signal, making it ideal for people who live in rural locations located between two towns. The downside to this type of antenna is that it has relatively low gain, meaning the towns should be located within a ten mile (16 km) radius. This type of FM antenna is often used a communication satellite.
The multi-element array antenna is perfect for those who live more than twenty miles (32.2 km) outside of town, as it has high gain and can receive very distant stations. Due to the fact that the gain of this antenna is directional, it must be rotated to receive different stations. This process can be made easier with the use of an antenna rotator system. Even in rural locations, when this antenna is mounted up high on a stake, it will receive the best FM radio reception available. Ample space is necessary to use a multi-element array antenna.
Indoor FM antennas are used for people who live in the suburbs, or urban areas, where residents wouldn't appreciate large, obtrusive antennas. A high-quality indoor FM antenna can receive excellent reception when positioned correctly. The downside to an antenna this strong, especially in an urban area, is that is picks up over modulated broadcasts, FM multi-paths and other interference, causing the reception to be noisy and distorted.