An Urchin‐Inspired Broadband and Ultralight Microwave Absorber

Abstract The incompatibility between low and high frequencies, and the constraints of thickness and absorption bandwidth, are great challenges for electromagnetic wave (EMW) absorbers. The combination of microscopic wrinkled morphology and macroscopic stacking structure offers the possibility of constructing lightweight and broadband EMW‐absorbing materials. Herein an artificial periodic unit is demonstrated, wCNT@PS/R, which consists of the urchin‐inspired wrinkled‐carbon nanotube (CNT)‐coated polystyrene (PS) spheres and the organosilicon rubber matrix. The unit thickness and the unit geometry are studied and optimized. Due to the good impedance matching, excellent macrostructural reflections, and strong dielectric loss, the pentagon unit achieves a promising effect absorption band (EAB) of 12.61 GHz, covering both the low‐frequency (S‐ and C‐band) and the high‐frequency (X‐ and Ku‐band) bands. The thickness is 4.0 mm and the total density is as low as 0.194 g cm −3 , which provides a new idea for the cost‐effective preparation of thin, ultralight, and broadband EMW absorbers.