The microwave absorption properties of soft magnetic materials in frequency up to 40 GHz

With the continuous development of communication technology, the microwave frequency used has been extended to 24∼30 GHz or even higher. Thus, for the research on microwave absorption materials, the commonly used 2∼18 GHz frequency range might no longer be enough. More studies of microwave absorption properties in a higher frequency band are necessary. In this work, we report the microwave absorption properties of several soft magnetic composites in frequency up to 40 GHz. Magnetic materials such as iron, Y2Fe16Si, Ce2Fe17N3−δ, and La2Fe4Co10B micron powders which display excellent microwave absorption properties in 2∼18 GHz, are investigated. Within 2∼40 GHz, the reflection loss (RL) of iron/paraffin, Y2Fe16Si/paraffin, Ce2Fe17N3−δ/paraffin and La2Fe4Co10B/paraffin composites could reach −46.2 dB, −71.4 dB, −49.1 dB, and −40.1 dB, respectively. Moreover, their effective absorption bandwidth (RL < −10 dB) could reach 16.9 GHz, 8.53 GHz, 10.08 GHz, and 8.03 GHz, respectively. Though the measurements are extended to 40 GHz, the absorption properties of these composites become weak when the frequency rises to around 40 GHz, which is restricted by the cutoff frequencies of the materials. The measured data shows that these soft magnetic composites are good candidates for high-frequency microwave absorption materials, while exploring magnetic materials with further higher cutoff frequencies may result in better performance.