Microwave absorbing performances of multiwalled carbon nanotube composites with negative permeability

The permittivity and permeability behaviors of composites made from the multiwalled carbon nanotubes with magnetic impurity Ni and the wax have been studied in 3-18 GHz. The unusual permittivity dispersion behaviors have been explained based on the Cole-Cole model and the conductivity contribution model. Permeability is found to have negative imaginary parts within 3-11 GHz. The composites are found to show good microwave absorbing performances (reflection loss <-20 dB): matching thickness is 1.5 mm and absorbing frequency band is 11.6-12.4 GHz, and the absorbing performance can be explained by the "geometrical effect." (C) 2007 American Institute of Physics.