Thermal Damage to the Skin From 5.6 GHz Microwave Exposures in Swine

Abstract

A study of burn thresholds from superficially penetrating radio-frequency (RF) energy at 5.6 GHz for swine skin was conducted. The study estimated the thresholds for superficial, partial-thickness, and full-thickness burn severities after 20 s of exposure at power densities of 4–8 W/cm². Biopsies were collected from each burn site at 1, 24, 72, and 168 h post exposure. Each sample was assessed by a burn pathologist against 20 histological factors to characterize the damage resulting from these RF overexposures. There were significant differences in the burn thresholds at the different severities compared to previous thresholds found at 8.2 and 95 GHz. A one-dimensional, layered digital phantom that utilized realistic values for dielectric and thermal properties was consistent with the observed damage trends and empirical dosimetry values. The results of the heating and cooling response of the animal model, and histology scores of each exposure are provided to establish damage thresholds and support development of simulation tools to predict parameters associated with RF hazards.