Friday, July 19, 2013

Applied sciences exclusive: Analyzing Pakistan's need for effective stealth countermeasures

by Faran Awais Butt via Terminalx. Shared under CC BY-NC-ND license 3.0.

Before I begin, I would like to familiarize the readers with two acronyms which I would use throughout this article: Electronic Counter Measure (ECM) and Electronic Counter Counter Measure (ECCM).

ECM is something that intends to disturb the normal working of a radar and ECCM refers to the efforts to overcome ECM. Jamming of the radar by noise or deception were the most notable amongst the ECMs but today, the radars of the world are under the threat of an even more sinister technology which is in possession of a very few countries; this technology, known as 'stealth', makes the target invisible to the radar. Stealth technology has brought up a revolution in the field of ECMs and has exposed the ineffectiveness of thousands of radars all across the world. The stealth aircrafts diffract and/or scatter very low power electromagnetic radiations owning to its special geometry and highly absorbent material. It is essential for the ground-based radars to have the capabilities of ECCM against stealth technology.

ECMs can be both seen and unseen. After World War II, there has been a significant research work on radar technology but as it progressed, its countermeasures also started to develop. The purpose of ECM is to make the radar less capable of detecting targets, deceiving the system and hence making it dysfunctional. It prevents the enemy radar from detecting the object. In reaction to ECM, there developed another form of electronic warfare which was developed as a reaction to ECM, known as ECCM i.e. electronic counter counter-measures of radar systems.

Electronic warfare is something in which every nation is trying to gain superiority at. There has been a rapid increase in sophistication of weapons in order to tackle the hostility of threats. ECCM is purely reactionary, that is, it has been developed in response to observed threats. If the ECM effects are observed in a specific system, a solution must be developed especially for a country like Pakistan which is under immense threat of this technology both from the western border (US, NATO forces) and India on the east.

Although stealth aircraft are in use and possess many qualities which make them superior to other fighter jets, however there still exist limitations to this technology. Many such aircraft are unstable and require a high-integrity sophisticated flight control and a fly-by-wire control system. The Radar Cross Section (RCS) of the aircraft is a parameter which dictates the detectability of the target. The greater the RCS, the easier it would be for the radar to detect it. Below 900 MHz, the target cross section increases exponentially. However, there is increased return from undesirable clutters. Shaping requirements have negative effect on the aerodynamics of the aircraft and hence they cannot be flown without a fly-by-wire control system. Hence, radar designers can exploit these vulnerabilities better than a mono-static radar since the bi-static RCS can be quite different depending upon target scattering characteristics.

The dramatic incident that took place on 2nd May 2011 at Abbottabad caused a humiliating disgrace to Pakistan when the United States' “modified” Blackhawk helicopters did a violation by covertly doing an operation at a strategically important location in Pakistan.

The report states that the latest stealth technology was used by the choppers employed in the raid. Helicopters with such technology are undetectable by ordinary radars.

The reports revealed that all of Pakistan Air Force's radar systems and technical monitoring assets were fully functional on 2nd May and no lapses of vigilance occurred that night on the part of the institution. This implies that there was lack of technology which resulted in the radars being unable to identify the incoming targets. It is evident thus, that radars are of no use if they cannot detect a target owing to ECM, which once again brings us to the conclusion that there needs to be an effective introduction of ECCMs into the system.

There is a global trend of using monostatic radars i.e. radars which have the same antenna which acts both as a transmitter/receiver and a duplexer which separates the signal. On the other hand, a bistatic radar is one in which there is a separate transmitter/receiver and the distance of the receiver should be considerable to the distance between radar and target. This trend needs to be changed for all the possible stealth-affected countries like Pakistan.

Stealth-oriented structures usually do not reflect the incoming wave in the same direction, rather they are absorbed and also scattered in different directions away from the radar.

These locations can be covered by use of multiple receivers at various locations. Pakistan should look for bistatic or a multi-static radar systems which have separated transmitters and receivers and whose receivers are located at a location comparable to the target’s distance.

Russia’s Sukhoi and Hindustan Aeronautics limited (HAL) are working on a project, 'Perspective Multi-role Fighter' (PMF), whose objective is to make Fifth Generation Fighter Aircraft (FGFA); these planes are expected to be in operation by 2015. India too, is working on autonomous unmanned combat air vehicles developed by the Defence Research & Development Organization (DRDO) for the Air Force.

Having already unveiled the J-20 Chengdu stealth fighter in January 2011, China is the only country which is developing two separate stealth fighters. The US is developing the F-35 Joint Strike Fighter in three versions; Russia is working on a single design, the 'PAK-FA', on which India is also collaborating. Separately, Japan is developing the ATD-X demonstrator.

Pakistan has a very fine air defence system against jamming techniques but there is a need to make efforts to overcome the threats of stealth. India has been working on stealth in collaboration with Russia where as Pakistan did not make any efforts to bring stealth technology to their system. Pakistan should seriously consider collaboration with China in the manufacturing of the'Mighty Dragon' J-20.

Efforts should be made by Pakistan to bring affordable stealth capabilities to their system. Although it must be acknowledged that this can take a lot of time. Pakistan should instead make efforts to build or design the counter to stealth system. The best radar that Pakistan has is the American TPS-77 which is a phased array radar. Phased array radars have many transmit/receive modules and such radars are very good in countering different types of noise jamming and to some extent, deception jamming. It also has a great deal of graceful degradation and room for modification according to situation.

Active phased array radars should be deployed since in such systems, there is a separate transmit/receive module which can be modified to have varied polarization, bandwidth and even operating frequency. Pakistan should look to work on active phased array systems in the radar factories at Kamra. Pakistan should also look to utilize radars operating on the lower side of L band of radar on the borders. Since building a multi-static radar approach could be very costly, we can either use modified radar warning receivers on a temporary basis or build a low cost multi-static radar system indigenously.

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