Abstract
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 electro-magnetic wave absorbing properties of double-layer absorbers (2 mm thickness), where multiwall carbon nanotube (MWCNT)-La(NO 3 ) 3 /polyvinyl chloride (PVC) and MWCNT-Fe 3 O 4 /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(NO 3 ) 3 /PVC composite were used as absorption layers with 0.6 mm thickness, the absorption bandwidth ( 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. DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16279
Highlights
With mounting electromagnetic pollution, electromagnetic wave absorbing materials have been paid much attention in recent years [1 – 6]
The samples were prepared by 8 mass % MWCNTLa(NO3)3 or multiwall carbon nanotube (MWCNT)-Fe3O4 hybrid materials that were homogeneously dispersed in polyvinyl chloride (PVC) matrix (MWCNTLa(NO3)3/ or MWCNT-Fe3O4/PVC), and made into a rectangular waveguide that has a length of 22.86 mm, a width of 10.16 mm for electromagnetic measurements
Composite have decreased with an increase of frequency, the real part is highest, and the imaginary part is lowest. This can be due to the interface and dipolar polarization and suggests that the dielectric loss of composites increases by adding La(NO3)3 and Fe3O4
Summary
Electromagnetic wave absorbing materials have been paid much attention in recent years [1 – 6]. Multilayer absorbing composites with gradient impedance, in which relatively more electromagnetic waves can be absorbed by impedance matching, are fabricated in order to broaden the absorbing bandwidths, enhance the absorbing intensity and improve the absorbing performance. Electromagnetic wave absorbing composites with a suitable absorption performance are usually designed with an appropriate matching layer. It is possible to achieve suitable impedance matching allowing incidents of electromagnetic waves to reach the absorbing layer with the free space [16 – 18]. We used MWCNTs doped with Fe3O4 and La(NO3) as an absorbent and insulating resin (PVC) as a matrix to fabricate double-layer composites for high-performance absorbing microwave.
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