Dielectric and electromagnetic wave absorbing properties of TiC/epoxy composites in the GHz range

The complex permittivity and reflection loss of TiC powders filled with epoxy resin were investigated in the frequency range of 2.6-18 GHz. Both the real and imaginary parts of the complex permittivity increased with increasing TiC content. A rapid increase in complex permittivity and strong frequency dependence characteristics was observed for the composite filled with high content of TiC. Based on the transmission line theory, single-layer and multi-layer absorbing coatings were designed. For single-layer coatings, the reflection loss below -5 dB (over 70% microwave absorbing) can be obtained in the frequency range of 13-18 GHz for the composite with 50 wt% TiC and 7-15.2 GHz for the composite with 60 wt% TiC. By optimizing the absorber structure and the associated thickness, the absorbing bandwidth of the multi-layer absorber can be largely broadened. The reflection loss below -5 dB can be obtained in the frequency range of 2.9-18 GHz for the four-layer absorber.