Double-layer electromagnetic wave absorber based on carbon nanotubes doped with la(NO₃)₃ and Fe₃O₄ nanoparticles

Double-layer structure absorbing materials based on the impedance matching principle and transmission line theory can effectively improve the electromagnetic wave absorbing properties. In this paper, the electromagnetic wave absorbing properties of double-layer absorbers (2 mm thickness), where multiwall carbon nanotube (MWCNT)-La(NO₃)₃/polyvinyl chloride (PVC) and MWCNT-Fe₃O₄/PVC composites had been taken turns as the absorption layer and matching layer, were investigated in 2 – 18 GHz range. The absorbing properties of single- and double-layer structure and different each-layer thickness with two types of combinations were compared. The results showed that the design of double-layer structure for composites could effectively broaden the absorption frequency area, and increase the absorption intensity. When MWCNT-La(NO₃)₃/PVC composite were used as absorption layers with 0.6 mm thickness, the absorption bandwidth (< – 15 dB or > 97 %) of double-layer composite was the widest, reaching a maximum of about 3.36 GHz, and the absorption peak value was also the lowest about – 46.02 dB at 16.24 GHz.