Influence of the CNT length on complex permittivity of composite laminates and on radar absorber design in X-band

Due to the high aspect ratio, CNT dispersed in polymer matrix composites makes large electric dipoles bringing about high dielectric constant, as well as dense percolation networks for electric conductivity. The length scale of the CNT has the definite influence on the internal structures of percolation networks, affecting the characteristics complex permittivity of the composites. In a Dällenbach type radar absorber made of a dielectric composite, the optimal thickness of lossy layer is dependent on the characteristics of complex permittivity. In this work, radar absorbers composed of E-glass composite laminates with CNTs of different length scales were developed in X-band. The design result demonstrates the influence of the CNT length on complex permittivity of composite laminates and on microwave absorber characteristics.