E-field errors associated with RF dosimeters for RF human exposure assessment in urban environments

Area of Science:

• Electromagnetics and Computational Physics
• Radiofrequency Engineering
• Human Exposure Assessment

Background:

• Body-worn radiofrequency (RF) dosimeters are crucial for assessing human exposure.
• Multipath environments, common in urban settings, can significantly impact RF field measurements.
• Accurate dosimetry requires understanding how the human body and environment affect RF fields.

Purpose of the Study:

• To analyze potential errors in body-worn RF dosimeters within a multipath environment.
• To statistically characterize RF power distribution in urban settings.
• To determine the impact of body presence on surface electric fields at various angles of arrival.

Main Methods:

• Statistical analysis of azimuth power distribution using 2D ray-tracing.
• Characterization of surface electric fields on a human body via the finite-difference time-domain (FDTD) method.
• Simulation of RF field interactions at 900 MHz under diverse multipath scenarios.

Main Results:

• Urban multipath environments exhibit specific azimuth power distributions.
• The human body's presence alters the surface electric field (E-field) distribution.
• At the dosimeter's location, E-field variations were similar but at least 5 dB lower compared to free space.

Conclusions:

• Multipath propagation and body interaction influence RF dosimeter accuracy.
• The reduction in E-field strength suggests a potential underestimation of exposure by dosimeters in certain conditions.
• Further research is needed to refine dosimetry models for complex environments.