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.