A frequency selective polarizer using carbon fibre reinforced polymer composites

Unidirectional carbon/epoxy composite laminates are highly orthotropic, with their conductivity and permittivity being strongly dependent on the incident angle relative to the fibre orientation. This paper presents a novel frequency selective polarizing subreflector manufactured from unidirectional carbon fibre reinforced polymer (CFRP), placed a certain distance from a conducting ground also made from CFRP laminate. Theoretical analysis, computational simulation, and experimental measurements are conducted to investigate the effects of separation offset, laminate thickness and incident angle on the performance of a reflector manufactured from a unidirectional IM7/977-3 CFRP. The results show that this new reflector reduces the cross polarization at S-band by 13 dB while remaining a good reflector at X-band and the incident angle has minimal effect on the frequency response of the polarizer. The single reflector can support two orthogonal polarized frequencies, unlike traditional wire grid polarizer screens.