This aerial is one of the aerials that are top selling, or most popularly constructed by advanced Amateur operators because it has such gain over other aerials. It also directs the signal in one direction, not just all around, making it stronger and also increases the reception of other stations in the general direction of where the aerial is pointed. The way to explain this is by saying that without a directional aerial the signal goes around 360 degrees. The difference with the Beam as stated before is that, it is directional, thus directing the signal in one direction and enhancing receiving distance as well. It is partly called a Beam because it beams the signal.
Beams get smaller in smaller in size as the frequency becomes higher and higher.
UHF beams tend to have more director and reflector elements as it's so much smaller and easier to fit. The dipole is another Horizontal aerial and also emits waves horizontally and is therefore horizontally polarized. The Dipole is usually strung between two poles, masts or trees and is connected at the middle. At both ends there are insulators so that the signal doesn't escape into the earth. The coaxial cable is connected in a special manner.