Thin magnetic coating for low-frequency broadband microwave absorption

摘要

Planar anisotropy carbonyl-iron (PACI) particles were prepared from 3 μm diameter sphere-shaped carbonyl-iron materials by high-energy ball milling technique. And the oriented planar anisotropy carbonyl-iron (OPACI) composite was fabricated using rotational orientation method. The OPACI composite possessed much higher real and imaginary permeability and relatively lower real and imaginary permittivity than other absorbers in 1-18 GHz frequency range. The susceptibility versus frequency curves have been fitted quite well using Kittel equation and Debye equation. Compared with natural resonance, the wall displacement susceptibility plays a dominating role for the high real and imaginary permeability. For OPACI composite, the minimum reflection loss (RL) can be as low as -44 dB at 1.8 GHz with the thickness of 2.3 mm, -7.3 dB at 1 GHz, -20 dB at 2 GHz, -5.4 dB at 8 GHz, and the bandwidth can reach 1.9 GHz for the good performance (RL ＜ -10 dB) in the frequency ranges of 1.2-3.1 GHz, indicating a promising absorber for low-frequency broadband application.