Editing Missile guidance (section)

=====Semi-active homing=====
{{Main|Semi-active radar homing}}
Semi-active homing systems combine a passive radar receiver on the missile with a separate [[targeting radar]] that "illuminates" the target. Since the missile is typically being launched after the target was detected using a powerful radar system, it makes sense to use that same radar system to track the target, thereby avoiding problems with resolution or power, and reducing the weight of the missile. [[Semi-active radar homing]] (SARH) is by far the most common "all weather" guidance solution for anti-aircraft systems, both ground- and air-launched.<ref name="Chapter 15. Guidance and Control">{{cite web|url=http://www.fas.org/man/dod-101/navy/docs/fun/part15.htm|title=Chapter 15. Guidance and Control|publisher=Federation of American Scientists}}</ref>

It has the disadvantage for air-launched systems that the launch aircraft must keep moving towards the target in order to maintain radar and guidance lock. This has the potential to bring the aircraft within range of shorter-ranged IR-guided (infrared-guided) missile systems. It is an important consideration now that "all aspect" IR missiles are capable of "kills" from head on, something which did not prevail in the early days of guided missiles. For ships and mobile or fixed ground-based systems, this is irrelevant as the speed (and often size) of the launch platform precludes "running away" from the target or opening the range so as to make the enemy attack fail.

[[Laser guidance|SALH]] is similar to SARH but uses a laser as a signal. Another difference is that most laser-guided weapons employ turret-mounted laser designators which increase the launching aircraft's ability to maneuver after launch. How much maneuvering can be done by the guiding aircraft depends on the turret field of view and the system's ability to maintain a lock-on while maneuvering. As most air-launched, laser-guided munitions are employed against surface targets the designator providing the guidance to the missile need not be the launching aircraft; designation can be provided by another aircraft or by a completely separate source (frequently troops on the ground equipped with the appropriate laser designator).