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Military stealth technology is not useless, it is just not as useful as the United States military thinks it is. When US stealth technology made its debut in Desert Storm, Soviet leaders were shocked by its effectiveness. American F-117s were able to sneak deep behind Iraqi lines and bomb targets with impunity.
Night after night throughout the war, F-117s bombed command and control centers deep in the heart of Baghdad, air defense installations spread throughout the country, and strategic infrastructures like bridges and power plants covered by some of Iraq’s most potent air defenses. All told. F-117s flew 1,300 sorties and attacked 40% of the strategic targets in the Gulf War.
However, stealth aircraft like the Lockheed F-117 is only optimized against certain frequencies. Historically, missiles have had to rely on high-resolution radars that utilize beams with wavelengths measured in centimeters and millimeters to target stealth aircraft. These frequencies are known as the SHF and EHF bands, respectively.
These SHF and EHF band radars are better at estimating the speed and location of non-stealth targets than radars that utilize longer wavelengths, therefore they can guide missiles more accurately. Stealth aircraft are optimized against targets in these bands, making it difficult to get a weapons-quality track on them.
No sooner than the dust had cleared over Baghdad did the Russians/Soviets begin work on counters to the US’s stealth technology. The Russians immediately recognized that stealth aircraft had a relatively poor performance against aircraft with wavelengths measured in meters or decimeters, operating in the VHF and UHF bands respectively. Modern stealth aircraft rely on honeycomb type structures in the aircraft skin to trap radar waves.
However, these longer wavelength radars produce beams that are too long to get trapped in these structures. Additionally, they tend to resonate off of defining features on the aircraft like the engine inlets or vertical or horizontal stabilizers, that is up to 10x the length of the radar that is observing them, producing a sizable return. Consequently, these radars can observe stealth aircraft with relative ease.
The U.S. Air Force retired the F–117 in April 2008, primarily due to the fielding of the F-22 Raptor. Despite the type’s retirement, a portion of the fleet has been kept in airworthy condition, and Nighthawks have been observed flying in 2020.
Nebo VHF-band AESA Radar Used in the S-400
However, historically these radars have suffered from poor resolution. UHF and VHF band radars have only been able to track targets within a few hundred meters, making them unsuitable for guiding missiles. Nevertheless, as the computer revolution has progressed, signal processing techniques have been developed that allow UHF and VHF radars to far more accurately fix the location of aircraft, making them more suitable for missile guidance.
The Russians have been able to develop radars like the Nebo VHF-band radar utilized in the S-400 that are capable of providing a weapons quality track or at the very least guiding a missile with an infra-red seeker to within a range, where it can autonomously locate and target an aircraft. As a result, radars have advanced to a point where aircraft like the F-117 would no longer be able to survive to perform missions like the ones they performed in Desert Storm.
E-2D Advanced Hawkeye
That being said, stealth technology is not useless. Radars like the Nebo radar used in the S-400 are enormous. They are simply too large to fit into most aircraft, aside from AWACS aircraft like the American Northrop Grumman E-2D and the Russian Beriev A-100. The Northrop Grumman E-2D utilizes a UHF-band radar, which has proven capable of guiding SM-6 missiles.
Nevertheless, these radars are far too large to fit into the most fighter, which is still largely dependent on radars in the SHF and VHF bands. Radars require many antennas to be able to effectively track targets, and every antenna must be the length of the wavelength that it emits. Fighter jets are simply incapable of carrying dozens of antennas that are meters long.
N036L-1-01 L-band AESA Radar
That being said, modern, Russian fighters like the Su-35 and the Su-57 are equipped with an L-band radar mounted in their wingtips that are believed to have some capability against stealth aircraft. The L-band is on the shorter end of the UHF band, representing radars with wavelengths between 15 and 30 cm. These radars should be capable of detecting defining features of stealth fighters like the F-22 and the F-35 by resonating off of defining features like engine inlets.
Northrop Grumman B-2 Spirit
Nevertheless, it is far more difficult to detect larger aircraft like the US B-2 with much longer defining features. The Northrop Grumman B-2 Spirit has a leading edge that measures about 33 meters in length. As such, it could only be detected by radar with a wavelength of at least 3.3 meters, which would put it in the VHF Band.
However, in recent years, the Russian Federation has brought online several powerful Voronezh radars operating in the VHF band that should be capable of tracking a B-2. These radars, however, are not designed to guide weapons. They are purely designed to identify targets approaching air space.
Nevertheless, these radars could be used to vector fighter jets to intercept B-2s. Given that the B-2 is relatively slow and unmaneuverable, it would be relatively defenseless against fighter jets with infrared search and tracking systems within visual range.