Stealth aircraft and anti stealth technology

Stealth and anti-stealth aircraft

1. STEALTH AIRCRAFT AND ANTI-STEALTH TECHNOLOGY NAVEEN KUMAR S 160982003 M.TECH(AEROSPACE ENGINEERING) INSTRUMENTATION AND CONTROL ENGINEERING DEPARTMENT

2. TABLE OF CONTENTS STEALTH AIRCRAFT GOAL OF STEALTH TECHNOLOGY RADAR RADAR CROSS SECTION REDUCED RADAR CROSS SECTION ANTI-STEALTH TECHNOLOGY DIFEERENT TYPES OF ANTI-STEALTH TECHNOLOGY REFERENCES

3. STEALTH AIRCRAFT ? Stealth aircraft are aircraft that use stealth technology to make it harder to be detected by radar and other means than conventional aircraft by employing a combination of features to reduce visibility in the visual, audio, infrared and radio frequency (RF) spectrum. Well known examples United States' F-117 Nighthawk (1980s-2008), B-2 Spirit "Stealth Bomber," F-22 Raptor.

4. Stealth technology relies on the principle of reflection and absorption that creates the objects stealthy . Stealth is accomplished by using a complex design philosophy to reduce the ability of an opponent's sensors to detect, track and attack an aircraft. The first combat use of stealth aircraft was in December 1989 during Operation Just Cause in Panama. On December 20, 1989 two USAF . F-117s bombed a Panamanian defence Force Barracks in Rio Hato, Panama. In 1991.

5. GOAL OF STEALTH TECHNOLOGY The goal of stealth technology is to make an airplane invisible to radar. There are two different ways to create invisibility: The airplane can be shaped so that any radar signals it reflects are reflected away from the radar equipment. The airplane can be covered in materials that absorb radar signals.

6. RADAR Radar is something that is in use all around us, although it is normally invisible. Air traffic control uses radar to track planes both on the ground and in the air, and also to guide planes in for smooth landings. NASA uses radar to map the Earth and other planets, to track satellites and space debris and to help with things like docking and maneuvering. The military uses it to detect the enemy and to guide weapons.

7. RADAR CROSS SECTION The Radar Cross Section (RCS) is a measure of the power scattered from a target to a certain direction, when the target is illuminated by electromagnetic radiation, i.e., a measure of how detectable a target is by radar. The fundamental form of the radar equation is as follows

8. RCS depends on the following Target geometry Target material composition, especially for the surface Position of radar antenna relative to target Angular orientation of target relative to radar antenna Frequency of the electromagnetic energy Radar antenna polarization.

9. RADAR CROSS SECTION REDUCTION The four basic methods of reducing RCS S haping U se of radar energy absorbing materials P assive cancellation A ctive cancellation

10. SHAPING The most important factor affecting the RCS is the geometry or the shape of the target, not its size. The surfaces and edges should be orientated in such way so as to reflect the radar energy away from an expected radar antenna and not back to it.

11. RADAR ABSORBING MATERIALS The idea behind the RAM is that of reflective a lightweight beam from a torch with a mirror. A usually used material is known as “ Iron Ball Paint ” . FSS (frequency selective surface) are used for filtration and microwave absorption. FSS can modify and improve the absorbing performances of RAM.

12. PASSIVE CANCELLATION Sometimes also mentioned as “impedance loading” . P assive cancellation is based on the idea of creating a (passive) echo source, whose amplitude and phase would be adjusted to cancel another echo source .

13. ACTIVE CANCELLATION Also called “active loading” . A ctive cancellation is based on the same principle as passive cancellation . W hich is the creation of an appropriate “destructive” echo, which would cancel the real echo of the target to the radar. This technique has been reported to be applied by the Rafale and has been implicitly confirmed by Dassault . The category of “active stealth” is the so-called “plasma stealth” technology.

14. ANTI-STEALTH TECHNOLOGIES Anti-Stealth technology radars uses the UHF/VHF waves to detect the stealth aircraft. Normal radars which uses the X-band and L-band waves in such band frequency the stealth aircraft does not get detected on the radars.

15. DIFFERENT TYPES OF ANTI-STEALTH TECHNOLOGY RADARS Multistatic radar Passive coherent location radars ESM (Electronic support measures) passive sensors Low frequency band radars 3D VHF radar AESA 1L119 NEBO SUV (Rosoboronexport, Russia) Over the horizon radars Infrared detection system

16. MULTISTATIC RADAR The multistatic approach (where there is one or more transmitter antennae and many receiver antennae, at different locations) has been proposed as a possible counter-stealth candidate. The main idea of the multistatic radar approach is that one or more receiver antennae will be in such a position to receive the scattered echo.

17. PASSIVE COHERENT LOCATION RADARS Systems of this category consist of receivers utilizing the existing radio waves . e.g., radio (SW, FM, DAB), TV (analog, DVB, HD), mobile telephony (GSM, 3G) and Wi-Fi.

18. ESM (Electronic Support Measures) Passive Sensors ESM systems are able to detect and locate targets, exploiting any radio transmissions from these targets

19. LOW FREQUENCY BAND RADARS L.o. aircraft have been designed with the aim to reduce radar energy backscatter mainly in the X and Ku bands. At lower frequency bands, the RCS of a l.o. aircraft is expected to increase . Another advantage that such radars offer is that they do not "warn" the targets they follow, since their transmission frequency is too low to be detected by an ordinary countermeasures system.

20. 3D VHF Radar AESA 1L119 NEBO SVU (Rosoboronexport, Russia). Developed by NNIIRT (Russia), the 3D surveillance radar NEBO SVU has been operational since 2004. It uses digital processing and solid state electronics, employing an array of 84 Yagi type antennae . Installed on a vehicle, it can be transported within 20 min.

21. OVER THE HORIZON RADARS If HF-band (3 – 30 MHz) waves are transmitted towards the ionosphere, under certain conditions, they may be reflected back to earth. The ionospheric reflection of the HF waves is the principle of operation of the Over-The-Horizon Radars (OTHR). E xtremely long detection ranges (from 700 to 4000 km) . Very low resolution.

22. INFRARED DETECTION SYSTEM The infrared (IR) area of the electromagnetic spectrum is the part between microwaves and visible light. It can be defined as the electromagnetic radiation with frequency from 300 Ghz to 400 THz . Wavelength from 1 mm to 0,75 μm. The targets are not warned, since there is no emission from the seeker. IR seekers cannot be jammed, like a radar seeker.

23. CONCLUSION A ll military aircraft, tanks, ships etc, are designed or redesigned according to low observable (l.o.) principles. S tealth aircraft are not invincible, they are just detected at shorter distances . The application of l.o. principles incurs a considerable cost, both in procurement as well as for maintenance. Stealth threat is a serious threat, which should be dealt with appropriately.

24. The Radar-Absorbent Materials (RAM) are not very effective at lower frequencies. The interceptors should be equipped with an IRST (InfraRed Search and Track) system, allowing detection and tracking of l.o. targets at longer distances, with respect to their radar sets .

25. REFERENCES V.K. Saxena, Stealth and Counter-stealth Some Emerging Thoughts and Continuing Debates, Journal of Defence Studies, 6(3),2012,19-28. S. VASS, Stealth technology deployed on the battlefield, AARMS,2000,257–269. D. Singh, A. Kumar, S. Meena, and V. Agarwala, Analysis of Frequency Selective Surfaces for radar absorbing Materials Progress In Electromagnetics Research B,2012, 38, 297–314. S. Cadirci,RF stealth (or low observable)and counter RF stealth technologies: implications of counter RF stealth solutions for Turkish air force ,naval postgraduate school, March 2009.