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A- and B- Band (HF- und VHF- Radar)
These radar bands below 300 MHz have a long historically tradition because these frequencies represented the frontier of radio technology at the time during the World War II. Today these frequencies are used for early warning radars and so called Over The Horizon (OTH) Radars. Using these lower frequencies it is easier to obtain high-power transmitters. The attenuation of the electro-magnetic waves is lower than using higher frequencies. On the other hand the accuracy is limited, because a lower frequency requires antennas with very large physical size which determines angle accuracy and angle resolution. These frequency-bands are used by other communications and broadcasting services too, therefore the bandwidth of the radar is limited (at the expense of accuracy and resolution again).

The F-35's approach to radar-absorbent material (RAM) is more reliable than that of any earlier warplane. The F-22's surfaces are made of aluminum, which are covered in RAM that must constantly be reapplied. This is, of course, a nightmare for maintenance crews. But the F-35 is made of carbon-fiber composite; Lockheed engineers bake RAM into the airplane's edges in an effort to soak up inbound radar.

The F-35 diminishes its visibility to radar with internal weapons bays, carefully aligned edges, and embedded antennas. Yet the airplane is accused of being more vulnerable to detection than earlier stealth aircraft, such as the F-22 Raptor, due to its more conventional airplane shape. Air Force Association president, retired Lt. Gen. Mike Dunn, slighted the F-35 when he stated that "only the F-22 can survive in airspace defended by increasingly capable surface-to-air missiles."

The F-35 is a multirole aircraft; it must fight other airplanes, bomb targets, and conduct recon; and each mission requires specific payloads. For that reason, its design has tradeoffs that make it less stealthy and less maneuverable than the Raptor, which was designed first and foremost to win air superiority over other fighters.

The F-35 does not have the radar-shunting curves of the Raptor that help mask it from radar at all angles. Engineers designed the F-22 and the B-2 to be unseen at many wavelengths and directions. The Lightning II does not offer many radar returns when the waves strike it from the front, but when they come from the side, the returns are stronger.

Radar waves do not just reflect off objects, they also flow across surfaces, scattering only when they hit a rivet, gun barrel, or other feature that breaks the smoothness of the skin. Aviation Week reporter Bill Sweetman notes that the F-35A's gun is located internally, but it is housed in a "hideous wart" on the airplane's surface—one of several features he says could betray the aircraft's position.

But the Lightning II's key to survival is its own radar, the Active Electronically Scanned Array (AESA) installed in its nose. Conventional radar systems turn their gaze mechanically—imagine a dish spinning or a flat surface tilting to aim radar beams. Electronically steered radar does not move, but its beams can broadcast in different directions, thousands of times a second and across many frequencies. This agility allows AESA to map terrain and track hundreds of targets.

AESA is built to do more than scan—it can reach out to enemy radars and scramble their signals. A combination of radar and electromagnetic warning sensors alert an F-35 pilot to the threat of enemy radar; he can then dodge the threat or use the AESA to jam the signal, no matter what frequency the radar is transmitting.

...Air dominance is now being fought in a greater swath of the electromagnetic spectrum. The critical part of any 21st-century air combat will be the first invisible duel of flickering AESA beams dancing across each other hundreds of miles ahead of any airplane. It's the same old dogfight rules: The first airplane to spot the other shoots, and quite likely whoever is in the other airplane dies.

Lockheed Martin F-22 Raptor