In this paper, the anisotropic conductivity effect of Quasi-Isotropic Carbon Fiber laminates on new type of conformal load-bearing antenna structure (CLAS), with slots being cut through a carbon fibre reinforced polymer (CFRP) laminate, is presented. The conductivity of a quasi-isotropic IM7/977-3 CFRP laminate is measured using the waveguide technique. The results show that orientation of the surface ply relative to the polarization of the E-field has a major influence on the reflectivity. This difference can be attributed to the fact that carbon fibres oriented parallel to the E-field plies behave as good conductors while off-axis plies as lossy dielectric layers with a finite conductivity. This anisotropic behavior of the ply layers is shown to have a distinctive influence on the operation of both microstrip patch and slot antennas.
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