The batteries were deployed to protect the southern cities of Beersheba, in the Negev Desert, and Ashkelon on the coast from Soviet-designed Grad rockets fired from the Gaza Strip, which is ruled by the Palestinian Hamas movement.
More than 80 rockets were unleashed from Gaza from Thursday-Monday after Palestinian guerrillas infiltrated Israel's southern border with Egypt.
But Iron Dome, which became operational in March, has radars built by the Israeli software company Elta Systems, a subsidiary of state-owned Israel Aerospace Industries, that compute the trajectories of incoming rockets and can determine where they will land.
The battle management and weapon control center, developed by mPrest Systems will only engage rockets heading for populated areas and fire Tamir interceptor missiles built by Rafael.
Each battery consists of three launchers equipped with 20 Tamirs and is reported to be able to protect an area of around 60 square miles. The system is designed to defend against rockets and artillery shells at ranges of 2-45 miles.
The successful interceptions of the last few days confirmed the system's operational capabilities that got their baptism of fire April 7 when Iron Dome made its first kill, downing a Grad heading for Beersheba.
That was the first time a short-range rocket had been intercepted in flight.
In the April action, the system destroyed nine Hamas rockets and missed one.
In the latest fighting, Iron Dome had its first operational failure. On Saturday, it shot down a volley of six but a seventh missile evaded the system and hit Beersheba, killing one man.
Following the April interceptions, militants in Gaza changed tactics in an effort to evade the two Iron Dome batteries deployed in southern Israel.
One tactic was to unleash volleys of 122mm Grads almost simultaneously, rather than individual launches, seeking to overwhelm the system. But, as far as can be determined, Iron Dome was able to handle the rocket swarms.
"This is the first system of its kind anywhere in the world, it's in its first operational test and we've already intercepted a large number of rockets targeting Israeli communities," Brig. Gen. Doron Gavish, the Air Defense Corps commander, said Sunday.
But he stressed, "We said in advance that this wasn't a hermetic system."
Military commanders say they need 10-15 Iron Dome batteries to effectively cover the main population centers and key military installations. Other estimates range as high as 20 batteries.
The Defense Ministry has accelerated the Iron Dome production timetable.
A third battery is to be deployed in early October, with a fourth due for delivery in six months. The air force is expected to get another two by the end of 2012.
Most of the budget for the four new batteries is covered by a special allocation of $205 million authorized by the U.S. Congress in May.
The military has said it will be investing around $1 billion to produce more Iron Dome batteries. Defense Minister Ehud Barak says he's working on an emergency plan to have nine batteries operational by late 2013.
Iron Dome is the lower tier of a four-layer missile defense network planned by Israel.
The Arrow 2 high-altitude, long-range system to counter ballistic missiles has been operational since 2000 and an upgraded version, Arrow 3, extending its range and altitude, is currently being developed. It was successfully flight-tested in July.
Medium-range missiles will be countered by a system known as David's Sling, which is under development by Rafael in Haifa.
At least two Asian states are reported to be "actively examining" the system. One is believed to be Singapore, which has had military links to Israel since the 1960s.
South Korea, which faces missile and artillery threats from the north, has also shown interest in recent months.
The Jerusalem Post reported recently the Israeli Defense Ministry is talking to several European countries about acquiring Iron Dome to protect their forces in Afghanistan.