Due to the compact and thin nature of metamaterial structures, they find
applications in designing absorber ranging from microwave to far infrared
frequency domain. The geometrical parameters are properly designed in such
a way that the input impedance of the structure matches with the
free-space impedance, thus creating minimum reflection. Initially,
split-ring resonator based structures have been proposed as metamaterial
absorbers, but the incident electromagnetic wave has to travel large
distance in that case; which is later replaced by electric field driven
(ELC) structures, where the incident wave has to travel only along the
thickness of the dielectric substrate on which the metallic patterns have
First, an ELC resonator driven metamateral absorber structure has been proposed which shows two distinct absorption peaks close to each other to achieve bandwidth-enhancement in C-band for airborne radar applications. The proposed structure comprises of an array with two different scaling factors of the basic unit cell. The structure behaves as polarization-sensitive absorber over wide incident angle. Thereafter, a single ELC structure exhibiting polarization-sensitive dual band absorption has been discussed. Later, it is modified to show triple band absorption in C-band. The proposed structure is polarization-insensitive in nature and supports wide angle absorptions. The measured results are in good agreement with the simulated results. Also, the constitutive electromagnetic parameters have been extracted to explain the absorption. After this, a triple band absorber with bandwidth-enhancement at X-band has been developed using square-shaped closed ring resonators over wide angle of incidence. The structure is polarization-sensitive in nature. The experimental results are again in good agreement with the simulated ones.
Finally, a broadband metamaterial absorber is presented with octave bandwidth for practical applications. The unit cell of proposed absorber structure consists of simple geometrical patches placed diagonally on the top surface of the structure. The proposed structure exhibits broadband absorption response covering the entire X-band with more than 90% absorptivity throughout. The roles of the geometrical parameters have been investigated to explain the principle of absorption. The structure is studied under oblique incidence for both TE and TM polarizations, where the broadband response holds good over wide angle in both the cases. The structure is fabricated and the experimental results are in good agreement with the simulated responses. The proposed structure is very thin (sub-wavelength with respect to the center frequency of the bandwidth) compared to the commercially available microwave absorbers.
Dr. Somak Bhattacharyya has obtained his B.Sc degree with Honours in
Physics from Scottish Church College, University of Calcutta in 2003. He
also obtained his B.Tech and M.Tech degree from Institute of Radio Physics
and Electronics, University of Calcutta in 2006 and 2008 respectively. He
has done his M.Tech thesis in collaboration with Giant Metrewave Radio
Telescope, Tata Institute of Fundamental Research, Pune. He has received
his PhD degree from Indian Institute of Technology, Kanpur in Electrical
Engineering Department in 2015. He is currently serving as faculty in
Electronics & Communication Engineering, Indian Institute of Information
His areas of interest are metamaterials, radio astronomical techniques, opto-microwave technology. He has received Young Scientist Award in "International Symposium on Electromagnetic Theory (EMTS) 2013"and in “Regional Conference of Radio Science” in 2015, both organized by International Union of Radio Sciences (URSI). He has published several papers in peer-reviewed journals and top level national and international conferences.