(a) Schematic diagram of sandwich structure metamaterial containing parallel arranged CF, where D is the spacing between adjacent CF, ω_m is the width of CF, and the thickness of CIP/PU resin matrix material above and below the CF is 0.5 mm, L and C represent the equivalent inductance and equivalent capacitance, respectively. RL of metamaterials of different spacing when CF (b) Parallel and (c) Perpendicular to incident electric field, respectively; the E-parallel and M-parallel represent the direction parallel to electric field vector and magnetic field vector, respectively.