Electromagnetic and microwave absorption properties of tunable carbonyl iron absorbing materials prepared by self-composite treatment in 2–8 GHz band

A novel fabricated method of low dielectric carbonyl iron (CI) composite absorbing materials, named self-composite, is designed in this paper. The composite absorbing material consists of spherical and flaky CI powders while flaky CI was directly prepared from spherical CI raw material by ball milling method. The results show that the reflection loss (RL) peak moves to high frequency with higher weight ratio of spherical CI. At the thickness of 1.5 mm, the (RL)min reaches − 16.5 dB at 5.56 GHz for composites mixed with the 40 wt% of raw CI. Moreover, the effective absorption bandwidth (< − 10 dB) of self-composite samples also increased significantly. Compared with 0 wt% sample, the effective bandwidth of the self-composite sample mixed with 40 wt% of the raw material is increased from 1 GHz to 3.56 GHz. The electromagnetic properties of composites can be adjusted by changing the content of raw CI materials. These changes led to an apparent improvement of impedance matching and then significantly improved the microwave absorptions. It is proved that the self-composite treatment can be applied to the low dielectric parameters absorbing medium required by S (2–4 GHz) and C (4–8 GHz) bands application, such as honeycomb structure absorbing material, radar, 5G communication, bluetooth, satellite communication, and so on.