Guided missiles have a number of different system components:
Guidance systems
Main article: Missile guidance
Missiles may be targeted in a number of ways. The most common method is to use some form of radiation, such as infrared, lasers or radio waves, to guide the missile onto its target. This radiation may emanate from the target (such as the heat of an engine or the radio waves from an enemy radar), it may be provided by the missile itself (such as a radar) or it may be provided by a friendly third party (such as the radar of the launch vehicle/platform, or a laser designator operated by friendly infantry). The first two are often known as fire-and-forget as they need no further support or control from the launch vehicle/platform in order to function. Another method is to use a TV camera—using either visible light or infra-red—in order to see the target. The picture may be used either by a human operator who steers the missile onto its target, or by a computer doing much the same job. One of the more bizarre guidance methods instead used a pigeon to steer the missile to its target.
Many missiles use a combination of two or more of the above methods,
to improve accuracy and the chances of a successful engagement.
Targeting systems
Another method is to target the missile by knowing the location of the target, and using a guidance system such as INS, TERCOM or GPS.
This guidance system guides the missile by knowing the missile's
current position and the position of the target, and then calculating a
course between them. This job can also be performed somewhat crudely by a
human operator who can see the target and the missile, and guides it
using either cable or radio based remote-control, or by an automatic system that can simultaneously track the target and the missile.
Flight system
Whether a guided missile uses a targeting system, a guidance system
or both, it needs a flight system. The flight system uses the data from
the targeting or guidance system to maneuver the missile in flight,
allowing it to counter inaccuracies in the missile or to follow a moving
target. There are two main systems: vectored thrust (for missiles that
are powered throughout the guidance phase of their flight) and
aerodynamic maneuvering (wings, fins, canards, etc.).
Engine
Missiles are powered by an engine, generally either a type of rocket or jet engine. Rockets are generally of the solid fuel type for ease of maintenance and fast deployment, although some larger ballistic missiles use liquid fuel rockets. Jet engines are generally used in cruise missiles, most commonly of the turbojet type, due to its relative simplicity and low frontal area. Turbofans and ramjets
are the only other common forms of jet engine propulsion, although any
type of engine could theoretically be used. Missiles often have multiple
engine stages, particularly in those launched from the ground. These
stages may all be of similar types or may include a mix of engine types -
for example, ground-launched cruise missiles often have a rocket
booster for launching and a jet engine for sustained flight.
Some missiles may have additional propulsion from another source at launch; for example the V1 was launched by a catapult and the MGM-51 was fired out of a tank gun (using a smaller charge than would be used for a shell).
Warhead
Missiles generally have one or more explosive warheads, although other weapon types may also be used. The warhead or warheads of a missile provides its primary destructive power (many missiles have extensive secondary destructive power due to the high kinetic energy of the weapon and unburnt fuel that may be on board). Warheads are most commonly of the high explosive type, often employing shaped charges to exploit the accuracy of a guided weapon to destroy hardened targets. Other warhead types include submunitions, incendiaries, nuclear weapons, chemical, biological or radiological weapons or kinetic energy penetrators. Warheadless missiles are often used for testing and training purposes.
Sumber:
http://astrophysicsblogs.blogspot.co.id/2012/12/building-missile-defense-system.html
