Dielectric properties of eight-harness-stain fabric glass fiber reinforced polyimide matrix composite in the THz frequency range

Electromagnetic wave transmittances of eight-harness-stain fabric glass fiber reinforced polyimide matrix composite with ≈1.1 mm thickness were measured in a terahertz (THz) frequency range using a terahertz time-domain spectroscopy (THz-TDS) system. The transmittance value is nearly zero at a frequency of 1.0 THz. The real part of the complex dielectric constant is 3.87 in the frequency range from 0.2 to 1.0 THz, and it is almost frequency independent. Conversely, the imaginary part of the dielectric constant linearly increases with increase of the frequency from 0.12 (0.2 THz) to 0.33 (1.0 THz). The dielectric properties of the eight-harness-stain fabric glass fiber reinforced polyimide matrix composite were also estimated from those of the E-glass fabric and matrix using a series model for the dielectric constant and the dielectric loss tangent.