Model of microwave radiation absorption by biological tissues

Abstract

А model of absorption of electromagnetic energy of radiofrequency range by biological tissues is described in the article. The problems of modeling the interaction of microwave radiation and biological tissues represented as multilayer structures are considered. Patch-antenna models for six sub-bands overlapping the 500–3500 MHz range are developed. The model of biological tissue was developed on the basis of MRI imaging, which allows for modeling under near real-life conditions. Based on the developed models of transceivers and biotissue, models have been created that allow to analyze the absorption of electromagnetic energy in the near- and far fields of the transmitter. From the results of modelling in the near field we can see that there are certain absorption maxima at frequencies of 750, 938, 1250 and 1357 MHz. Based on the results of the far field modeling it can be noted that in the range of 750 to 1000 MHz there is no absorption peak at 938 MHz. Also, as a result of the simulation, a decrease in the magnitude of absorption starting from 750 MHz was registered. Absorption peak absence is also observed in the area of 1357 MHz frequency. In the range of 2.5–3 GHz both in the near and far fields practically linear decrease of absorption value is observed. When analyzing the influence of structures' sizes on electromagnetic energy absorption in biological tissues, it was found that the nature of change in absorption value is a nonlinear value. In the range of 0.5–2 GHz both increase and decrease of absorption at thickening or thinning of layers is observed. It should also be noted that when the size of each layer increases by 10 %, the peak of absorption in the area of 1156 MHz frequency is observed. For the 2–3.5 GHz range there are no significant changes in the chart shape when the layer thickness changes.