Broadband and strong microwave absorption combining excellent EMI shielding of VGCF/carbonyl iron composites derived from synergistic magnetic and dielectric losses

Abstract

As one of the most effective approaches to reduce microwave radiation in electromagnetic stealth and compatibility, broadband microwave absorbers have attracted widespread attention. However, it is challenging to maintain broadband absorption performance and maintain thin thickness simultaneously. Herein, by cooperating electromagnetic characteristics of vapor-grown carbon fiber (VGCF) and flaky carbonyl iron particles (CIP) to manipulate complex permittivity and complex permeability, a broadband metastructure absorber is proposed. The local conducting network composed of VGCF enriches the transmission path and greatly boosts dielectric loss capability of VGCF/CIP composites. The constructed VGCF/CIP reinforced metastructure absorber covered the 95% (−13 dB) absorption bandwidth in the full frequency band of 2–18 GHz at 8.4 mm thickness. The outstanding microwave absorption performance is benefit from the synergistic effect of magnetic-dielectric characteristics of the VGCF/CIP composite. The result provides a multi-resonant coupling mode to improve the overall impedance matching characteristics, which opens up a broad prospect for the development of ultra-wideband microwave absorbing materials. Moreover, VGCF/CIP composite shows a high electromagnetic interference (EMI) shielding effectiveness, and the excellent green shielding index (gs) of more than 10 indicates its potential application as an EMI shielding material.