Broadband Wide angle Polarization insensitive Metamaterial Absorber for K band application

Abstract

This paper focuses on the design and analysis of a strictly polarization-insensitive with broad angular stability broadband metamaterial absorber for the application of the K band. The unit cell of the metamaterial-absorber consisting of a symmetrically arranged ladder shape structure of copper is imprinted on a metal-backed FR-4 substrate. Wide absorption bandwidth of 7 GHz ranging from 21.20 GHz to 28.20 GHz, covering the K-band, is observed under normal incidence. The absorption capability of the proposed structure is more than 91% for TE and TM polarized waves under normal incidence. Electromagnetic field and surface current distribution (Top and Bottom) are exhibited to understand the absorption mechanism of the proposed structure. The proposed design is four-fold symmetric and shows polarization insensitivity for different angles of $\Phi$ from 0° to 90° for TE and TM polarized waves. Moreover, the structure illustrates more than 60% absorption under oblique incidence angles from $\theta=0^{\circ}$ to 90° for both TE and TM polarized waves. The thickness of the proposed absorber is $\lambda 0/8$, corresponding to the center frequency, making it compact and suitable for commercial applications like Radar Cross Section reduction and energy harvesting applications in the K band.