Specific Anthropomorphic Mannequin

Description

The Specific Anthropomorphic Mannequin is a computational model representing the human head or body, used in electromagnetic simulations to assess the interaction between a radiating device, like a mobile phone or base station, and human tissue. It is defined by a detailed geometric mesh, including distinct tissue types such as skin, fat, muscle, bone, and brain, each with assigned complex permittivity (dielectric properties) at specific frequency bands. This model is implemented in simulation software to solve Maxwell's equations, typically using the Finite-Difference Time-Domain (FDTD) method, to calculate the distribution of absorbed RF energy.

The primary output of a SAM simulation is the Specific Absorption Rate (SAR), measured in watts per kilogram (W/kg). SAR is a measure of the rate at which energy is absorbed by the body when exposed to an RF electromagnetic field. For handheld devices, simulations place the SAM in standardized positions against the head (cheek and tilt positions) or beside the body to determine peak spatial-average SAR. For base stations or other equipment, the SAM is used to evaluate power density exposure in the vicinity of the antenna. The SAM's standardized geometry and tissue parameters ensure that different laboratories and manufacturers obtain comparable and reproducible results, which is critical for regulatory certification.

3GPP specifications, particularly those developed by RAN4 (Radio Access Network Working Group 4), reference SAM models for conformance testing of User Equipment (UE) and base station RF exposure. The specifications detail the exact mesh resolution, tissue properties for frequency ranges from 300 MHz to 6 GHz, and the simulation methodology. By using a SAM, 3GPP provides a clear, technical foundation for demonstrating that wireless devices operating within its standards comply with international safety guidelines set by bodies like the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronics Engineers (IEEE).

Purpose & Motivation

The SAM was developed to create a unified, scientifically rigorous approach for evaluating RF exposure compliance across the global telecommunications industry. Before standardization, manufacturers and test labs used various proprietary phantoms and methodologies, leading to inconsistencies in SAR measurements and difficulties in comparing results. This lack of harmonization posed challenges for regulatory approval and raised concerns about the reliability of safety assessments.

The adoption of the SAM in 3GPP standards addresses these issues by providing a common reference model. Its purpose is to ensure that all devices tested for compliance with 3GPP radio standards are evaluated against the same benchmark, promoting fairness, reproducibility, and technical accuracy. This is especially important as device form factors become more complex (e.g., foldable phones, wearable devices) and as networks use higher frequency bands (like mmWave in 5G), where exposure characteristics change. The SAM enables the industry to proactively assess safety using computational modeling, which is often more flexible and comprehensive than physical measurements alone, supporting the rapid development and certification of new wireless technologies.