Microwave Absorber Made of Hanoi-Tower Shaped Dielectric Resonators and a Magnetic Support

This paper presents a 3-D printing-compatible wideband absorber with high angular robustness. A periodic structure, composed of Hanoi-Tower shaped resonators, is fabricated with a lossy 3-D printable dielectric material using additive manufacturing, and glued on a magnetic elastomeric material. Exploiting the resonating modes in the periodic resonators, high absorption is achieved over a large bandwidth. The resonators' shape and dimensions are chosen accordingly to the material properties so that a high angular robustness is reached. Moreover, the presence of a magnetic support enhances the absorption capabilities of the structure, specially for the TM polarization, where a reflectivity below -10 dB for most incident angles over the 4–12 GHz band is reached. Finally, diffraction phenomena happening at high frequencies are studied, showcasing that high-order diffraction can be avoided by reducing the size of the structure and increasing the permittivity of the dielectric material.