Material Investigation on Radio Frequency Transparency and Thermal Stress Relaxation

An investigation on thermally resistant and radio frequency (RF) transparent materials was performed. Thermal stress relaxation tests from 20°C to 150°C showed that polystyrene foam board and polycarbonate demonstrate signs of creep deformation over time. Polyurethane foam demonstrated no thermal stress relaxation. For RF penetrability testing, the 100 MHz to 40 GHz range was studied using an outdoor test setup. Open air measurements of two collinearly faced antennas were compared to measurements taken when material samples were placed between the two antennas. This demonstrated that rigid polyurethane foam, Teflon polytetrafluoroethylene (PTFE) and borosilicate glass are RF penetrable.