IIT Mandi's new research might become a new shelter on battleground

India’s tanks, warships, military aircraft, and establishments may soon be able to camouflage from enemy's radars, with a new radar-absorbing material developed by researchers at the Indian Institute of Technology (IIT), Mandi in Himachal Pradesh.

The indigenously developed material absorbs a wide range of radar frequencies (signals), irrespective of the direction from which the radar signal hits the target. The radar absorbing cover works on Frequency selective surfaces (FSS), which involves modifying the electromagnetic wave to provide signals with dispersive transmitted or reflected characteristics.

Once this material is placed on an object it absorbs any incoming signal and restricts or prevents any radar signature. Thereby providing prevention from radar. This can be used to cover windows or glass panels of stealth vehicles and covert establishments to protect them from all types of radars that work in C, X, Ku and Ka frequency bands.

As per the tests conducted by the institute, the technology can absorb more than 90 per cent of the radar waves in a wide range of frequencies. The research team performed experimental studies on their design and the results matched well with the theoretical analysis.

“We have used an array of resonators which are etched on a transparent sheet. These resonators are designed in a specific shape to resonate and absorb frequency signals irrespective of their polarization or the angle of incident. Further, the transparent sheet which we have used is Polyethylene Terephthalate/PET sheet on which we have engraved our resonator structure using laser engraving technology,” said Dr G Shrikanth Reddy, Assistant Professor at IIT Mandi.

The proposed design uses an optically transparent Indium tin oxide coating on a PET (thermoplastic) sheet with the FSS patterns. The FSS pattern on the PET sheet was created with laser engraving technology, and due to the symmetrical and lossy nature of FSS patterns, the proposed absorber is polarization insensitive and absorbs electromagnetic waves.

Reddy said the cost of the lab prototype was very less. “The technology is indigenous, so the manufacturing cost will be less.”  The research work was started in 2017 by Dr Awanish Kumar, who was then a PhD student at the institute. The team now has three members.  

Radar-absorbing materials are crucial for defence applications as they can reduce or eliminate the radar signature of military equipment, such as aircraft, ships, and vehicles. In addition, it can also be used to protect critical infrastructure such as communication towers, power plants, and military bases from radar detection.

But the researchers believe that the material can also be applied for several commercial use cases. This can include reducing radiation leakages from industrial buildings and making them more secure or even protecting buildings critical for information security and privacy.

“These materials can be used for defences and civilian companies which work on covert activities. Also, the circuit or electronic chip industries can use this for Electromagnetic compatibility (EMC) or electromagnetic interference (EMI) tests. Since we are at the initial stage we have not approached any private organization. However, we are in touch with government organizations to seek final applications,” Reddy said.

EMI and EMC are widely conducted in regulatory testing and compliance of electronic and electrical products.

The research was also published in the journal of the Institute of Electrical and Electronics Engineers (IEEE’s) Letters on Electromagnetic Compatibility Practice and Applications. IIT Mandi has nine Academic Schools and four major Research Centers. Since its inception, the institute’s faculty have been involved in over 275 Research and Development (R&D) projects worth more than Rs. 120 crores.