How Iron Dome Air Defense System Work?

Iron Dome has three components: the detection and radar installation, battle management and weapons control (BMC), and the missile firing unit itself.
The Iron Dome defense system fires to intercept incoming missiles from Gaza in the Israeli port town of Ashdod on Nov. 15, 2012. The system can fire clusters of missiles simultaneously to intercept multiple incoming targets.
 The radar system detects opposing missiles or artillery shells when they are launched.
The BMC is the brain of the system. It calculates the trajectory of the rocket and where it is expected to hit. The BMC is capable of tracking and firing at multiple targets simultaneously.
If an incoming rocket is headed to a low-risk area, like an empty field, Iron Dome will leave it alone. But if a rocket is on a path to a sensitive target, like a populated area, Iron Dome launches a Tamir missile that can intercept and destroy it.
The system also figures out the best place to intercept the incoming target along its trajectory, to try and avoid debris falling on populated areas.
Incoming targets travel extremely fast, and the trajectory calculations and decision to launch are done within seconds.
The Tamir interceptor missiles cost about $40,000 US each, and can be fired day or night and in any type of weather. They are guided for the first part of their flight by the radar system and BMC on the ground, which keeps them on course.
When the Tamir nears its target, the missile's own onboard radar takes over to take it as close as possible to the incoming rocket or shell. The warhead it carries explodes, destroying both the Tamir and the incoming target.