On June 2, an Iranian military Mi-17 helicopter flew over the desert east of Tehran toward one of the most secretive facilities belonging to the Iranian Revolutionary Guard Corps. The helicopter landed in a remote area near two buildings surrounded by huge wire nets. Guests disembarked.
Brig. Gen. Farzad Ismaeli, commander of Iran’s air-defense force, and several masked IRGC personnel, waited to introduce a new radar system—one that could be able to detect American stealth warplanes at long range.
Ismaeli described the complex of wire nets and buildings as the Ghadir radar, Iran’s first operational over-the-horizon sensor. OTH radars can detect stealthy and small targets at very long ranges, regardless of the target’s altitude.
It’s a capability that promises to dramatically improve Iran’s ability to detect and defend against an aerial attack, potentially altering the military balance of power in the Persian Gulf.
For years, OTH radars have formed the back bone of territorial defense for the world’s superpowers. The United States currently operates an OTH radar network that can spot target as far as 3,000 kilometers from U.S. shores.
Australia, a potential target of Chinese strategic bombers, has the new Jindalee OTH sensor, with a similar range.
To achieve such incredible performance, OTH radars take advantage of a unique natural phenomenon. Instead of emitting radio waves directly into the target space, OTH radars blast very long wave pulses into the ionosphere.
Waves of certain frequencies bounce back down to the target area, enabling the radar to look at objects from above and identify them even behind ground terrain such as hills and mountains.
In addition to detecting stealth warplanes, OTH radars can also pick out ballistic missiles and even satellites in low orbit. Their long range makes them impervious to small-scale attacks by anti-radiation missiles and jammers.
On the down side, OTH radars are bulky, immobile and imprecise. The distance error in detecting a typical target can be as high as a kilometer. OTH radars also need enormous power sources.
Compared to other countries’ OTH radars, Ghadir seems to possess modest performance. Ismaeli claimed it has an 1,100-kilometer range and a maximum detection altitude of 300 kilometers.
Ghadir has four transmitters for 360-degree coverage, but given the huge amount of energy they require, it’s not clear that all four can broadcast at once. The phased-array layout closely resembles the Soviet Duga-3 radar near Chernobyl, perhaps indicating a fairly old-style design.
Ismaeli announced a plan to construct a more powerful OTH radar called Sepehr that could feature a 3,000-kilometer range.
Ghadir is unlikely to survive very long in an intensive war with the United States, but in the case of a limited engagement such as an American attack on Iran’s nuclear facilities, the OTH radar could help Iran organize its defenses.
The sensor would likely recognize an aerial strike package long before it reached Iranian borders, giving people enough time to evacuate essential facilities, alerting air-defense crews and prompting the air force to launch defensive fighters.
Ghadir should be able to cover all of Saudi Arabia. The more powerful Sepehr could also detect targets inside Israel. Both systems could prove a boon to Iran’s ally Syria.
The United States, Israel and Saudi Arabia have no way of countering the new radar short of a full-scale attack. America has poured much of its military research effort into stealth aircraft, but OTH radars by their nature negate the stealth advantage.