IIT Kanpur Develop new Protective Layer for Microwave Metamaterial Absorbers

Kanpur: Researchers at the Indian Institute of Technology, Kanpur (IITK), have developed a novel "Protective Layer for Microwave Metamaterial Absorbers and Method Thereof," that has got the Indian patent number 445111. The breakthrough invention is led by the team consisting Dr. Kajal Chaudhary, Senior Student Research Associate at the Department of Electrical Engineering; Prof. Janakarajan Ramkumar, Department of Mechanical Engineering; Prof. S. Anantha Ramakrishna, Department of Physics; Prof. Praveen C. Ramamurthy, Department of Materials Engineering, Indian Institute of Science, Bengaluru; and Prof. Kumar Vaibhav Srivastava, Department of Electrical Engineering, IIT Kanpur. This novel invention is poised to transform various sectors, ranging from defense to daily living, by addressing a crucial challenge in electromagnetic wave absorption technology.

In an era of heightened waves and radar-based technologies, the ability to
detect objects through reflected waves has become increasingly accurate. However, certain applications—both military and civilian—require concealing the
presence of materials. This has led to intense research into microwave metamaterial electromagnetic absorbers, particularly those utilizing transparent
conductive films in their design. However, the use of such films, like Indium tin
oxide coated polyethylene terephthalate (ITO-PET) sheets, has been hindered by
their susceptibility to scratches and subsequent loss of conductivity over time,
undermining their performance and lifespan. The new invention addresses these
limitations.

Prof. Abhay Karandikar, Director IIT Kanpur said, “In today’s fast-changing
world, effective technological integration is key. This novel patent is a
breakthrough in the field of electromagnetic wave absorption technology. It
signifies not only a remarkable technological stride but also a testament to the
potential collaborative efforts across disciplines can bring. It holds the promise of
making our environments safer, more secure, and less polluted by
electromagnetic radiation. It can have a far-reaching impact globally.”

This patent introduces a groundbreaking solution for electromagnetic wave
absorption. “The current invention is a protectively coated transparent
microwave metamaterial absorber that can directly be employed on optical
transparent windows for electromagnetic wave absorption. Different countries
use RADAR detection technologies at microwave frequency bands for detection
of any object by sensing the waves reflected back from them. The continuous
electromagnetic radiation in the environment from Wifi, cell phone tower, radar,
diagnostic medical equipment, and other electronic/communication systems, are
dangerous for health. The proposed protective transparent sheet is capable of
absorbing more than 90% of the incident electromagnetic waves at microwave
frequency,” says Prof. Kumar Vaibhav Srivastava, Department of Electrical
Engineering, IIT Kanpur.

The novel coatings, named PVB and APTES/PVB, bolster the mechanical
reliability of metamaterial absorbers while preserving their optical and
microwave capabilities. The result is a metamaterial absorber that remains
robust even under harsh environmental conditions and rigorous handling,
without compromising its microwave performance over time. Notably, coating
the absorber led to a significant increase in absorption efficiency within
microwave frequency range, rising from 95% to an impressive 98%.

This innovation has far-reaching implications for a multitude of fields. The newly
safeguarded transparent microwave metamaterial absorber can be applied
directly to optical transparent windows, making them capable of absorbing over
90% of incident electromagnetic waves at microwave frequencies. This
translates to both stealth applications in defense and a means to combat
electromagnetic pollution caused by the proliferation of radiation-emitting
devices. Unlike earlier designs prone to scratching, this patented protective
coating retains the electrical and optical properties of the absorber, rendering it
reliable under adverse conditions.

This patent stands at the confluence of various scientific disciplines, including
Material Science, Electrical Engineering, Mechanical Engineering, and Physics. Its implications extend beyond the patent itself, offering a rich dataset for further
research across these fields. Moreover, companies keen on advancing these
methods and tools can explore opportunities for future scaling and adoption.