Microwave absorption properties of amorphous Fe–B particle composites in K band

In this study, spherical amorphous Fe–B submicron particles were synthesized via aqueous chemical reduction, and a composite with a mass fraction of 80% was prepared by compounding them with polyurethane. By measuring the electromagnetic parameters and calculating the microwave absorption properties, we found that the composite had excellent absorption performance in a frequency range of 18–26.5 GHz. When the absorber was 0.88 mm thick, the reflection loss (RL) peak reached a maximum (−47.94 dB) with a bandwidth (RL < −10 dB) of 5.01 GHz. The absorption mechanism of the composite in the K band was also investigated. The results showed that the Fe–B particle composite effectively reduced the absorber’s thickness, maintaining a good absorption performance in the K band.