Assessment of incident power density in different shapes of averaging area for radio-frequency exposure above 6 GHz

Abstract

Overview

The standards set by the International Commission on Non-Ionizing Radiation Protection and IEEE C95.1-2019 are crucial for safeguarding humans from electromagnetic field exposure at frequencies above 6 GHz, focusing on both absorbed (epithelial) power density (APD) and incident power density (IPD).

Objective

Commencing with a clear purpose, the study rigorously evaluates the impact of averaging the IPD and APD over different geometric shapes - specifically square versus circular areas - providing pivotal insights aligned with exposure standards.

Approach

Employing computational assessments using the finite-difference method, relationships between APD, IPD, and the consequent steady-state temperature rise (heating factor) are explored for varied exposure models involving dipoles and Gaussian beam scenarios.

Main Results

• Differential heating impacts of up to 4.4% were noted between square and circular averaging areas, predominantly when the exposure model's beam pattern possessed an elliptical configuration.
• For closer ranges (≤5 mm) and lower frequencies (≤15 GHz), square averaging areas tended to underrepresent the conservative nature of circular areas by as much as -7.8% concerning IPD.

Significance

This analysis confirms that the heating impacts for circular averaging areas deliver a reliable safety measure for near-field exposures up to 300 GHz, supporting the alignment of exposure with product safety standards, particularly in scenarios where the beam geometry exhibits considerable angular deviation.