A parameter used to specify the width of the maximum beam of an antenna. It is usually the half-power beamwidth, which is the angle between the two directions in which the radiation intensity is one-half the maximum value of the main beam, where the direction of the maximum and the half-power points are in the same plane. If it is used otherwise, such as the angle between the 10-decibel points, the specific points on the antenna pattern should be described.