Can the F-35 Lightning II Be Tracked Down By Radar ?
This is a very complicated issue but in Short Yes They Can !
There are some major misconceptions regarding Stealth mainly the myths that the Stealth plane is invisible more accurate description is that stealth makes the aircraft smaller when radar waves hit an object they will reflect back in different directions depending on the object's shape since aircrafts have very complicated shapes with the wings cockpit vertical stabilizers bombs etc, is almost guaranteed that some of the radar waves will be reflected back to the radar station,
Stealth is a whole field of study dedicated to reducing the amount of radar waves that are reflected back to the radar receiver this is accomplished in two main ways first the shaping of the aircraft to deflect the radar waves away, and the second is coating the aircraft with a material that can absorb the radar waves, the amount of radar waves an object reflects back to the receiver is measured by what is called its radar cross section or RCS a typical fourth generation fighter has an RCS of approximately 5 to 10 square meters whereas a stealth aircraft will have an RCS thousands of times smaller,
Radar detection range is in proportion to the fourth root of its RCS so for example if a radar can detect A-10 square meter object from 100 miles away and an object with an RCS of 1 square meter would not be detected until it is 56 miles away and with a cell fighter like the F-35 with an estimated RCS 2,000 times smaller it wouldn't be able to be detected by that radar until it was within 15 miles now these detection ranges vary drastically depending on the frequency of the radar being used lower frequencies have longer waves some measuring several feet long longer waves are much more likely to detect these stealth aircraft this is because to absorb radar waves and not to reflect them the thickness of the coating is proportional to the length of the waves so a lower frequency radar with a wave that is several feet long would require the aircraft to have several foot thick coating completely surrounding it to absorb the radar obviously this is not realistic for a fighter jet
This is a way which the Russians and Chinese can detect the American stealth aircraft with lower frequency radars and these types of radars where the kind used to shoot down the Stealth F-117 in Yugoslavia back in 1999, the surface-to-air missile site used a Russian lower-frequency T18 radar to detect and track the stealth jet the P18 radar uses a frequency with waves approximately 10 feet long which is way too long to be absorbed by the F-117 stealth coating,
However there are several problems with lower frequency radars one is that creating such a long low frequency wave requires very large antennas the size of the antenna again is directly proportional to the frequency you can create such large radars are too big to be carried by aircraft so they need to be stationed on the ground and large radars are typically less mobile in that their locations can be known and simply avoided by the stealth aircraft another issue is that they are much less precise than higher frequency radars because of the long waves is much harder to pinpoint the exact location of the aircraft and is typically not precise enough to guide to interceptor missile to shoot down the aircraft,
The F-117 shoot down was an exception to this mainly because it was within only a few miles of the radar and as stated earlier Stealth does not make an aircraft invisible just not able to be detected until it's much closer, and finally passive radar can be used theoretically to detect Stealth aircraft basically passive radar is similar to active radar except it does not send out its own radio waves to relies on other transmissions like AM or FM radio television or even GPS signals the radar receiver can detect these transmissions and also the reflection of these transmissions off the aircraft and then calculate its location based on the time deference
This technique is beneficial mainly because the stealth aircraft are designed to be stealthy against the most commonly used military radar frequencies so using a variety of different frequencies from different sources can better detect the aircraft this technique however is very complicated and typically requires more receivers to triangulate the aircraft's location it also requires extremely sensitive receivers as the transmission and signals are typically much weaker than active radar.
