Radar Beam
fan beam
Figure 1: Different main lobes of the antenna pattern of a ship's radar, partly pencil beams but also fan beams
fan beam
Figure 1: Different main lobes of the antenna pattern of a ship's radar, partly pencil beams but also fan beams
fan beam
Figure 1: Different main lobes of the antenna pattern of a ship's radar, partly pencil beams but also fan beams
Radar Beam
A directional radar antenna concentrates the transmitting energy in a narrow sector. This sector is described by the points at which the transmitted power was reduced by half. The area within these half-power points is defined as the radar beam, and it contains nearly 80 percent of all the transmitted energy. It is usually a cone-shaped cutout from a sphere, mostly sharply focused (pencil beam), but sometimes much wider in one dimension (fan beam).
With continuous wave radar, this geometric form is completely filled with the transmitted power. With very short transmission pulses, this section is not completely filled with the transmission energy, but only a small volume, the so-called resolution cell. A radar beam is then the path that guides the travel of the transmitted impulse.