telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that ...

s and

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...

engineering, antenna boresight is the axis of maximum

gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in de ...

(maximum radiated power) of a directional

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

. For most antennas the boresight is the axis of symmetry of the antenna. For example, for axial-fed

dish antenna A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or ...

s, the antenna boresight is the axis of symmetry of the parabolic dish, and the antenna

radiation pattern In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the ''directional'' (angular) dependence of the strength of the radio waves from the antenna or other source.Constantine A. Balanis: “A ...

(the main lobe) is symmetrical about the boresight axis. Most antennas boresight axis is fixed by their shape and cannot be changed. However phased array antennas can electronically steer the beam, changing the angle of the boresight by shifting the relative phase of the radio waves emitted by different antenna elements, and even radiate beams in multiple directions (multiple boresights). The term ''boresight'' came from

high-gain antenna A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources. Directional antennas provide increased performanc ...

s such as parabolic dishes, which produce narrow, pencil-shaped beams which are difficult to aim accurately at a distant receiving antenna. These often are equipped with optical boresights to assist in aiming.

References

Antennas (radio) {{telecomm-stub