Polarization Independent Interconnected Split-Ring Resonator with Enclosed F Shape Metamaterial Absorber for Wireless Technology.

In this article, a polarization-insensitive, flexible and ultrathin metamaterial absorber (MMA) has been presented with six absorption peaks in S-band, C-band, X-band, and Ku-band. The proposed absorbers’ geometry consists of $90^{0}$ rotated and connected four outer square split rings. Each outer split ring consists of rotationally symmetric two split square rings and a circular split ring. Each outer ring has a F shape in the core of the middle. FR-4, a generally accessible, low-cost substrate material with a dielectric constant of 4.3, was used to create the MMA unit cell. The unit cell size is $10 \times 10 \mathrm{~mm}^{2}$. The absorption peaks of this absorber greater than $90 \%$ at $3.088,4.77,9.88,11.23$, $13.34,17.39$, and 18.23 GHz, respectively. The suggested absorber is insensitive to polarization and incidence angle since it is symmetrical. The proposed structure shows steady absorption over azimuth and elevation angles, specifically phi=0 to 90 degrees and Theta $=0$ to $\mathbf{6 0}$ degrees, and its refractive index is almost zero or negative. The absorber unit cell has a tiny and compact design, measuring $0.12 \lambda \times 0.12 \lambda$ in size and with an extremely thin thickness of $0.016 \lambda$. Here, $\lambda$ represents the wavelength at the absorption peak with the lowest frequency. The absorption phenomena of the absorber have been proved by analyzing the input impedance, E-field, and surface current distribution characteristics.