Flower-like Multi-Shell Hollow Microsphere Enhances Dielectric-Magnetic Synergy for Efficient Microwave Absorption in C-Band

Achieving efficient microwave absorption in the C-band (4–8 GHz) is of great significance for reducing wireless communication interference and enhancing radar stealth performance. In this work, flower-like multi-shell hollow microsphere (FMSHS) composed of magnetic NiO/Co 3 O 4 heterostructures were successfully fabricated using a sequential template method combined with an ion competition strategy. The experimental results indicate that at a thickness of 3.4 mm, the FMSHS achieves a reflection loss as low as −71.40 dB at 6.80 GHz, with an absorption bandwidth reaching 6.48 GHz, demonstrating excellent microwave absorption performance. Its superior microwave absorption capability in the C-band is primarily attributed to the enhanced magnetic-dielectric synergistic effect resulting from the simultaneous improvement in polarization loss and magnetic loss. Furthermore, the multi-shell hollow structure significantly improves the impedance matching characteristics, facilitating the effective penetration of microwaves into the material rather than reflecting off its surface. Meanwhile, the multiple reflections and scattering effects induced by the flower-like surface and multi-shell hollow structure prolong the propagation path of microwaves within the material, thereby enhancing microwave absorption efficiency. This study provides insights into the morphological design and performance optimization of microwave absorbing materials for the C-band.