A horn antenna is an antenna used to guide radio frequency (RF) microwave signals in a particular direction as they go out into the air. By controlling the direction of the waves, they can cover a greater distance with more accuracy. This can help information travel longer distances in a shorter amount of time in a more reliable fashion.
In the age of computers, these types of transmission techniques are particularly important in times of disasters. RF microwaves do not require much power and the horn antenna requires no power. This allows for signals to be transmitted using a low-level generator if something should happen to the main power source. A horn antenna is often used in the American Midwest to transmit tornado information and to activate tornado-warning sirens.
Horn antennas also can be utilized to relay information over even greater distances by having a relay system in place. This would allow for a signal to be sent from one place, received in the next and then retransmitted, possibly in another direction. In theory, this could connect an entire country during a mass natural disaster, keeping information flowing even if the disaster becomes more widespread.
Much like HAM radios, horn antennas are an older technology that is still quite useful. During the Haiti earthquake in early 2010, people were quickly reminded of how easily phone communication via land lines and cellular phones can be cut off. The use of a horn antenna lets information reach great distances, making the situation clear and allowing others to be better prepared to help.
Gain horn antennas take the horn antenna to the next level. They are used to keep in touch with objects in space. RF microwaves travel even without atmosphere and can be utilized to track and to communicate with satellites and other orbiting objects. Gain horn antennas require a special coating to handle the stronger waves being transmitted. A lens also is used to help focus divergent energy and keep it moving in the correct direction.
Gain horn antennas are often used in secure military communication systems and in planes. These are particularly relevant in point-to-point radio links and in anti-collision programs on airplanes. Even small personal aircraft rely on horn antennas to provide accurate information about movement in the surrounding area. It helps them to avoid obstacles, whether the moving or stationary variety.