Evaluation of microwave shielding characteristics of quasi-isotropic carbon fiber reinforced plastic laminates based on unidirectional materials

The microwave shielding characteristics of quasi-isotropic carbon fiber reinforced plastics (CFRP) based on unidirectional (UD) materials are experimentally evaluated. First, fundamental characteristics of a UD CFRP laminate and a quasi-isotropic CFRP laminate are discussed. Second, shielding and polarization characteristics of a simple UD CFRP laminate are measured between 400 MHz and 6 GHz. The UD CFRP laminate, which has a same fiber direction, operates as a wire-grid and has more than 30 dB polarization ratio. Then, the dielectric constants of the fabricated CFRP laminate are measured by using the impedance analyzer. However, it was not suitable to describe whole wire-grid characteristics of the UD CFRP laminates. Finally, the measurement result of the quasi-isotropic CFRP laminate shows more than 40 dB shielding characteristics, which is almost the same as the dynamic range of the measurement system.