Modulatable electromagnetic response toward ultra-strong, broadband microwave absorption and devices

Against the backdrop of booming 6G-enabled Internet of Things and intelligent manufacturing, electromagnetic (EM) functional materials are shifting from single-performance optimization to multi-scenario adaptive integration. Herein, a series of FeNi@C-x (x = 4, 8, and 12, which represents the polyvinylpyrrolidone dosage in the preparation process) core-shell composite with controllable modulation of particle size and dispersion is fabricated using polyvinylpyrrolidone as a bifunctional structure-directing agent. This tailored architecture enables efficient synergy of dielectric-magnetic losses, optimizing impedance matching and achieving excellent microwave absorption and electromagnetic interference (EMI) shielding. Specifically, FeNi@C-8 delivers a minimum reflection loss of −67.60 dB, and radar cross-section simulations confirm its efficient EM wave attenuation capability. FeNi@C-4 achieves an EMI shielding effectiveness of 41.4 dB and realizes green EMI shielding. Notably, the superior EM absorption performance enables the conception of waste EM energy harvesting and recycling devices. Serving as a dielectric substrate, FeNi@C not only endows the planar helical antenna with tunable ultra-low return loss, switchable radiation direction and ultra-wide beam coverage across the S/C/X/Ku bands, breaking the coverage limitation of traditional hemispherical antennas, but also enables the design of a two-way equal T-junction microstrip power divider that suppresses surface wave crosstalk and improves port isolation via material-level EM attenuation to meet the demand of high-precision wireless communication. This work provides a new path for the integrated design of multifunctional EM materials and devices, with promising applications in high-precision radar and wireless communication, EM protection, intelligent equipment and EM energy utilization.