Design of Artificial Electromagnetic Absorber

This paper presents a novel polarization-insensitive metamaterial absorber based on a spherical unit cell. The performance of the absorber is evaluated using CST, a 3D full-wave electromagnetic simulation tool, under normal incidence for both TE and TM polarization modes. The spherical geometry of the unit cell allows the absorber to maintain approximately 90% stable absorption efficiency for both TE and TM modes within the 1-2.5 GHz frequency range. To improve absorption at lower incidence angles, a spherical cavity was introduced at the center of the unit cell, and surface-mount resistors (SMD) were positioned on top of the spherical structure. The spherical design was chosen because it offers the same surface area across all angles in spherical coordinates, enabling uniform absorption. The absorber is constructed using a plastic sphere with a radius of 60 mm and a thickness of 4 mm, featuring copper traces connected by SMD resistors. Our findings indicate that spherical-shaped metamaterials can provide superior absorption performance over a wide range of incident angles, making them highly effective for various electromagnetic applications.