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<p>Electromagnetic wave interaction with biological tissue is frequency-, angle-, and polarization-dependent, influencing both dosimetric parameters and resultant thermal effects. This work presents a comprehensive analysis across the major ISM bands (433, 915, 2450, and 5800 MHz) for transverse electric (TE) and transverse magnetic (TM) polarizations incident on a three-layer tissue model (skin–fat–muscle). A custom MATLAB code was developed to integrate the multilayer transmission line formalism, polarization-specific wave impedance modeling, Cole–Cole dielectric parameterization, and a finite difference method (FDM) solution of the Pennes bioheat equation. Simulations were performed for incident power density 50 W/<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\hbox {m}^2\)</EquationSource> </InlineEquation> and fat thicknesses from 0.005 m to 0.03 m, over incidence angles 0&#xa0;°C– 80&#xa0;°C. Throughout the manuscript, reflection is reported strictly as a <i>power</i> quantity <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(R=|\Gamma |^2\)</EquationSource> </InlineEquation> rather than a field-amplitude coefficient. The thermal pipeline solves the steady-state Pennes equation in its direct <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\Delta T\)</EquationSource> </InlineEquation> form with consistent surface (Robin) and deep (Dirichlet) boundary conditions, and simulations are audited by an energy-conservation budget. Results indicate that while temperature increases remain below 0.4&#xa0;°C at lower frequencies (433–915 MHz), significant superficial heating (up to 3.5&#xa0;°C) occurs at 5.8 GHz due to reduced penetration depth, even at moderate exposure levels. The results demonstrate that subcutaneous fat acts as a low-loss impedance transformer whose thickness strongly modulates the balance between reflection and internal absorption, while polarization and angle primarily tune the detailed shape of angular reflection curves (including TM Brewster-like minima) at a given incident power. The analytical framework therefore complements voxel-based full-wave numerical models by providing fast, physically transparent trends across ISM bands that are directly relevant for preliminary assessment of wearable devices, implanted sensors, and compliance with radiofrequency safety limits.</p>

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Parametric analysis of electromagnetic wave interactions with layered biological tissues for varying frequency, polarization, and fat thickness

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  • 发表日期：

    2025年12月26日

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  • Akram Gasmelseed

摘要

Electromagnetic wave interaction with biological tissue is frequency-, angle-, and polarization-dependent, influencing both dosimetric parameters and resultant thermal effects. This work presents a comprehensive analysis across the major ISM bands (433, 915, 2450, and 5800 MHz) for transverse electric (TE) and transverse magnetic (TM) polarizations incident on a three-layer tissue model (skin–fat–muscle). A custom MATLAB code was developed to integrate the multilayer transmission line formalism, polarization-specific wave impedance modeling, Cole–Cole dielectric parameterization, and a finite difference method (FDM) solution of the Pennes bioheat equation. Simulations were performed for incident power density 50 W/ \(\hbox {m}^2\) and fat thicknesses from 0.005 m to 0.03 m, over incidence angles 0 °C– 80 °C. Throughout the manuscript, reflection is reported strictly as a power quantity \(R=|\Gamma |^2\) rather than a field-amplitude coefficient. The thermal pipeline solves the steady-state Pennes equation in its direct \(\Delta T\) form with consistent surface (Robin) and deep (Dirichlet) boundary conditions, and simulations are audited by an energy-conservation budget. Results indicate that while temperature increases remain below 0.4 °C at lower frequencies (433–915 MHz), significant superficial heating (up to 3.5 °C) occurs at 5.8 GHz due to reduced penetration depth, even at moderate exposure levels. The results demonstrate that subcutaneous fat acts as a low-loss impedance transformer whose thickness strongly modulates the balance between reflection and internal absorption, while polarization and angle primarily tune the detailed shape of angular reflection curves (including TM Brewster-like minima) at a given incident power. The analytical framework therefore complements voxel-based full-wave numerical models by providing fast, physically transparent trends across ISM bands that are directly relevant for preliminary assessment of wearable devices, implanted sensors, and compliance with radiofrequency safety limits.