Devkinandan Chaurasiya

An Ultrawideband Ultrathin Metamaterial Absorber Based on Circular Split Rings

A simple design model for making ultrawideband ultrathin metamaterial absorber has been presented in microwave frequency regime. The proposed structure is composed of two concentric circular split rings imprinted on a metal-backed dielectric substrate. A 10-dB absorption bandwidth from 7.85 to 12.25 GHz covering the entire X-band has been observed in numerical simulation under normal incidence. The absorptivities of the proposed structure have been investigated under different polarization angles as well as oblique incidence. The electromagnetic field distributions and surface current plots have been illustrated to analyze the absorption mechanism of the proposed structure. The proposed absorber has been fabricated and its performance is experimentally verified at different angles of incidence and polarizations of incident electromagnetic wave. The designed absorber is compact, ultrathin (only λ0/15 thick corresponding to center frequency) and provides an alternative to construct broadband absorber for many potential applications.

An ultra-thin triple band polarization-insensitive metamaterial absorber for C-band applications

An ultra-thin triple band polarization-insensitive metamaterial absorber has been presented in this paper. The unit cell of the proposed structure consists of three concentric rings in the top layer of metal-backed dielectric substrate. The simulated result shows that the proposed structure has triple band absorptivity response lying in C band. The structure exhibits polarization-insensitive behavior under normal incidence due to four-fold symmetry. It also shows high absorption under oblique incidence upto 60° for both TE polarization (above 75%) and TM polarization (above 90%), thus validating the wide angle characteristics. The absorption mechanism is explained through illustrating the electric and magnetic field along with the surface current distribution. The proposed structure has been fabricated and measured, which shows good agreement with simulated response, thus verifying the polarization-insensitivity and wide angle characteristics.

An ultra-thin polarization independent compact fractal shaped metamaterial absorber

In this paper an ultra-thin polarization-independent compact metamaterial absorber has been proposed where the unit cell contains single fractal shaped square structure. The geometrical dimensions of the fractal structure have been designed in such a way that the structure exhibits absorption at 4.17 GHz and 11.16 GHz. Due to the four-fold symmetry of the structure, the absorber is polarization-independent in nature. The proposed structure has been studied under oblique incidences for TE and TM polarizations where it behaves as absorber upto 45° incident angles in both the cases. The structure is only 1.6 mm thick (~ λ0/17 with respect to higher absorption frequency), making it ultra-thin in nature.

Design of a wideband absorber using resistively loaded frequency selective surface

A wideband radar absorber comprising single-layer resistively loaded frequency selective surface (FSS) is presented in this paper. The FSS is printed on a thin dielectric substrate separated from the metal ground by an air spacer. Numerical result shows that the proposed absorber provides 10 dB absorption bandwidth over the frequency range of 3.96 - 13.36 GHz, which is equivalent to 108.54%. Moreover, the designed structure is polarization-insensitive and wide angle absorptive. Additionally, the equivalent circuit model and several parametric variations are investigated to explain the absorption mechanism of the structure.

A broadband polarization-insensitive circuit analog absorber using lumped resistors

In this paper, a broadband circuit analog absorber has been presented based on lumped resistors, which exhibits 10 dB absorption bandwidth from 3.96 GHz to 8.16 GHz, covering entire C-band. The designed structure is polarization-insensitive and wide-angle absorptive. The effect of the lumped resistors has been studied to examine the absorption mechanism of the wideband absorber. The structure has also been fabricated, whose measured results are in good agreement with the simulated responses.