With the development of the 5G applications, micrometer and millimeter microwaves have been full filling the space around people. They not only interfere with tons of electronic devices but damage human health as well. To combat these problems, there is an urgent need for microwave absorption materials. However, most of the research on microwave absorption materials stays within the 2~18GHz frequency range, while the 5G millimeter microwave’s frequency can reach up to 24GHz or higher. Thus, 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 40GHz. Common materials such as iron, Y2Fe16Si, Ce2Fe17N3-δ, La2Fe4Co10B micron powders which experience excellent microwave absorption properties in 2~18GHz are included. Within 2~40GHz, the reflection loss(RL) of iron/paraffin, Y2Fe16Si/paraffin, Ce2Fe17N3-δ/paraffin and La2Fe4Co10B /paraffin composites could reach -46.2dB, -71.4dB, -49.1dB, and -49.0dB, respectively. And their effective absorption bandwidth(RL<-10dB) could reach 16.9GHz, 8.53GHz, 10.08GHz, and 7.4GHz, respectively. Though the measurements are extended to 40GHz, the RL of most of these materials could not maintain a low level at 40GHz, 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 a better performance.
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Fig.1 The RL curves with the broadest effective absorption bandwidth of different composites.
Fig.2 The RL curves with the minimum RL of different composites.