An open-ended waveguide system for SAR system validation or probe calibration for frequencies above 3 GHz

Area of Science:

• Electromagnetics
• Biomedical Engineering
• Wireless Communication

Background:

• Personal wireless devices require compliance with specific absorption rate (SAR) safety guidelines for electromagnetic power absorption.
• Current SAR measurement systems use planar phantoms and lossy fluids to simulate tissue dielectric properties.
• Accurate validation of SAR systems and E-field probe calibration is crucial for Wi-Fi frequencies (5-6 GHz band).

Purpose of the Study:

• To introduce and validate an open-ended waveguide system for SAR measurements.
• To assess the system's performance for Wi-Fi frequencies in the 5-6 GHz band.
• To compare experimental SAR data with numerical methods for accuracy.

Main Methods:

• Development of an open-ended waveguide system as a broadband irradiator.
• Utilization of a planar phantom with a 2.0 mm base filled with lossy fluid.
• Application of a fourth-order polynomial least-squares fit to experimental data.
• Comparison with finite-difference time-domain (FDTD) numerical method.

Main Results:

• Experimental SAR variations near the phantom's bottom surface showed excellent agreement with FDTD simulations.
• Experimentally determined peak 1-g and 10-g SAR values were within 1-2% of FDTD results.
• The system demonstrated high accuracy at 5.25 GHz and 5.8 GHz.

Conclusions:

• The described open-ended waveguide system is a viable tool for SAR system validation and E-field probe calibration.
• The system provides accurate measurements for Wi-Fi frequencies, ensuring safety guideline compliance.
• Experimental and numerical methods show strong concordance, validating the proposed measurement approach.