Comparative studies of radio transparency and dielectric characteristics of polymer composites

Aramid-epoxy composites and glass fiber reinforced plastics are widely used in the manufacturing of the fairing design for modern aerospace vehicles due to their excellent mechanical properties combined with radio transparency in wave transfer. In this paper, aramid-epoxy composite and fiberglass were fabricated by the vacuum infusion method for a comparative study on radio transparency and dielectric characteristics. The radio transparency of the studied materials was evaluated by free-space measurements in the frequency range of 1 GHz to 8.5 GHz. According to the radio transparency results, the aramid-epoxy composite undergoes less electromagnetic wave loss than glass fiber reinforced plastic. Modifying the epoxy resin with tricresyl phosphate in aramid-epoxy resin leads to an increase in mechanical properties with a slight decrease in transmittance and a non-significant increase in dielectric characteristics. The dielectric characteristics results have demonstrated low values (ε = 2.87 and tan δ = 0.037) for aramid composites compared to fiberglass.