Microwave absorbing material based on rice husk ash/ CNTs composites

This paper presents the different type of microwave absorbing materials based on rice husk ash and carbon nanotubes (RHACNTs) composites. The microwave absorption and complex relative permittivity of RHACNTs composites were investigated in microwave frequency region X-band (8.2-12.4 GHz). A rectangular waveguide (WR-90) transmission line method was used to measure scattering parameter and Nicolson-Ross-Weir algorithm to calculate the complex relative permittivity (ε\´_r- jε"_r) of RHACNTs samples. The microwave absorption properties of rice husk ash with carbon nanotubes (0-5 wt %) was measured the modes of waveguides with perfectly conducting enclosures with metal backed plate. It was observed that the increase of carbon nanotubes (CNTs) influenced the ε\´_r and ε"_r values. However, the different MAMs of RHACNTs composite have difference microwave absorption more than -10 dB at specify frequency. The complex relative permittivity and thickness of materials are important parameters for the microwave absorbing properties.