The technology designed into the F-35 dates back to 1996. That is when its
development contracted was enacted. Stealth technology has changed
since then, but the F-35 has, thus far, not kept up to date.
A major problem for the F-35 is that it is designed to have a stealth
capability confined primarily to X-band. That is the band wave covered
by the APG-81 radar of the aircraft. However, this
leaves it susceptible to detection and tracking by other radars.
The Lockheed F-35 is equipped with an expendable radar decoy (the BAE
ALE-70) that can be towed, or be free flying. Its defense is limited to
emergency situations to prevent a missile from locking
onto the aircraft. It has very limited electronic anti-detection and tracking technology.
When the F-35 was on the drawing boards, Lockheed calculated that low-band
stealth, limited jamming, and passive electronic surveillance were
sufficient for an aircraft that would be deployed by 2010.
They didn't take into account the delays in aircraft development, along with
advances in stealth detection technology. Had defensive electronic anti
detection upgrades since been added to the F-35 program, they would
have been one of the areas being blamed for rising prices and delays.
Therefore it is reasonable to assume that no new electronic anti
detection stealth technology has been added to the original Lockheed F-35 design.
Whereas past technology VHF analog, mechanical, radars are negated by original
F-35 technology, new high power VHF AESA (Active, Electronically Scanned
Array) radars, and ultra high frequency wave trackers are not.
Aircraft stealth doesn't make them undetectable, rather stealth
aircraft deflect radar so as to lower the amount of returned signal.
Some of the signal still finds its way back to the radar, but it is
weak. The concept of stealth is to have the return signals lower
than the filtration level of radar controlling computers. In order
to filter out false positives, older radars filtered out return
signals that appear too small to be an aircraft.
It is said that the F-35 has the radar return the size of a small
bird. Today there are radars like Iron Dome that can detect small
rockets and artillery shells in flight, guiding missiles or guns to down them.
Radars can distinguish between small, slow, low flying objects and small, fast, high flying objects, as birds will
not be flying at jet-like speeds and altitudes. If a radar picks up
a small object flying fast and high, it will not be a bird.
Depending on its flight behavior, not size alone, the type of vehicle can be distinguished.
A low band radar can detect the F-35, but alone can not hone in
on its position close enough for interception. A high band radar
and/or infra red sensors will have to be used in conjunction with the
low band radar for missile guidance. An example of how these work
together are the L-band radars carried by the Russian stealth fighter
that provide information to the aircraft's other sensors that can
hone in on its target. Around high-value ground targets, an entire
network of radars can work together to cover the sky.
Advanced Chinese Radar
Active electronically scanned array (AESA), sometimes called active phased array radar (APAR), with ranges of up to 500
km, using high speed electronics combining continuous wave and pulse
transmission emitted in short intervals, are capable of almost
continuous targeting objects such as the F-35. A modern radar network can scan all around the
sky several times a second. It will be able to track multiple
targets at once, distinguishing them from clutter, guiding missiles and guns to lock on their targets.