Beyond visual range

A beyond-visual-range missile (BVR) is an air-to-air missile (BVRAAM) that is capable of engaging at ranges of 20 nmi (37 km) or beyond. This range has been achieved using dual pulse rocket motors or booster rocket motor and ramjet sustainer motor.

In addition to the range capability, the missile must also be capable of tracking its target at this range or of acquiring the target in flight. Systems in which a mid-course correction is transmitted to the missile have been used.

Early air-to-air missiles used semi-active radar guidance, that is the missile used the radiation produced by the launching aircraft to guide it to the target. The latest generation of BVR missiles use a combination of semi-active and active radar.

The first such missiles were relatively simple beam riding designs. The Sparrow 1 mounted on the US Navy's Skyknight became the first operational BVR missile in 1954. These primitive BVR missiles were soon replaced by missiles using semi-active radar homing (SARH). This is where the launching aircraft's radar is "locked" onto the target in a single target track (STT) mode, directing a radar energy at the target that the missile seeker can "see" as it reflects off the target. The radar antenna must "illuminate" the target until impact. Missiles like the Raytheon AIM-7 Sparrow and Vympel R-27 (NATO designation AA-10 'Alamo') home in on the reflected radiation, much as a laser-guided bomb homes in on the reflected laser radiation. Some of the longest-range missiles in use today still use this technology.

The first air-to-air missile to introduce a terminal active seeker of its own was the AIM-54 Phoenix carried by the F-14 Tomcat, which entered service in 1972. This relieved the launch platform of the need to illuminate the target until impact putting it at risk. The Phoenix and its associated Tomcat radar, the AWG-9 was capable of multiple track and launch capability, which was unique to the Tomcat/Phoenix until the advent of AMRAAM in 1991.

...
Wikipedia