Infrared Thermography In Experimental Dosimetry Of Radio Frequency And Millimeter Wavelength Radiation Exposure

Distribution of 800-1500 MHz and 37-78 GHz microwave absorption in biological tissue phantoms and real biological objects was studied using method of Infrared Thermography. Multicomponent and 0.1-0.2 mm thin-layer phantoms were irradiated in near and far field of radiating antennas. SAR distribution was calculated as the function of initial heating rate. Temperature sensitivity was better than 0.02 K at up to 60 frames per second sampling rate. It was found that nonuniform SAR distribution could appear in near field area due to a geometrical resonance resulting from a secondary wave-mode interaction between an irradiated object and the corresponding critical cross-section of the horn antennas, and due to the biological heterogeneity. Local SAR in hot-spots can significantly exceed the spatially averaged values. These findings provide an explanation for a number of frequency-dependent and for so-called non-thermal effects of microwaves.