Surface and Internal Temperature versus Incident Field Measurements of Polyurethane Based Absorbers in the Ku Band
In recent years there has been an increased need for testing antennas and radar systems at high power. Since absorbers work by transforming electromagnetic energy into thermal energy there is a danger that in the presence of high fields the absorber will reach temperatures that will cause it to ignite. In the present paper standard polyurethane absorber is illuminated by a conical horn antenna. Different field levels are used to illuminate the sample. The internal and surface temperature of the sample is measured. From these measurements a behavior of the temperature versus field can be determined. Absorbers with and without a rubberized surface coating are also investigated to study their thermal behavior. This becomes very useful in determining if higher power materials may be required for testing active arrays or radar systems. The effects of lowering the temperature of the absorber by using airflow across the tips are also studied.