Simple method to measure power density entering a plane biological sample at millimeter wavelengths

Area of Science:

• Electromagnetics and Applied Physics
• Biophysics and Bioengineering
• Measurement Science and Instrumentation

Background:

• Accurate measurement of microwave power density is crucial for controlled electromagnetic field exposure studies.
• Near-field exposure presents unique challenges for power density determination.
• Existing methods may lack precision or applicability in specific near-field scenarios.

Purpose of the Study:

• To present a simple and applicable method for measuring microwave power density in near-field exposure.
• To enable precise calibration of power density for sample exposure.
• To derive formulas for calculating specific absorption rate (SAR) based on measured power density.

Main Methods:

• Development of a transmitted power method for calibrating power density at the sample surface.
• Utilizing incident and reflected powers within a waveguide for power density determination.
• Calibration performed using liquid samples within a quartz cell.

Main Results:

• A straightforward calibration procedure for microwave power density in near-field applications.
• Established relationship between power density, incident/reflected powers, and sample dielectric properties.
• Derived formulas for calculating specific absorption rate (SAR) with accompanying error analysis.

Conclusions:

• The described method provides a simple and effective means to measure microwave power density for near-field sample exposure.
• The technique facilitates accurate SAR calculations, essential for electromagnetic bioeffects research.
• The method's applicability is demonstrated for liquid samples, with potential for broader use.