Meaning
Specific absorption rate testing measures the highest localized rate of radiofrequency energy absorption in biological tissue per unit mass. Portable wireless device evaluations identify localized peak SAR by scanning miniature electric field probes inside tissue-equivalent liquid phantoms. Physical evaluations apply exclusively to body-worn or head-adjacent wireless hardware operating below six gigahertz.
Probe Scanning
Automated robotic arms move field probes along a three-dimensional grid near the inner phantom surface. Interpolation algorithms convert spatial electric field measurements into cubic one-gram or ten-gram volume averages. Hotspot location shifts as beamforming arrays alter phase distribution among individual elements.
Thermal Budget
Conductive paths within product enclosures alter local current distribution and near-field energy concentration. Metal shield cans, battery enclosures and internal flex cables act as secondary re-radiating elements that move peak absorption points. Physical layout modifications must maintain distance between peak current nodes on the main board and external enclosure walls.
Internal control algorithms dynamically throttle RF power when proximity sensors detect human contact, preventing localized peak SAR from exceeding statutory limits.
Compliance Standard
Certification filings present measured peak values alongside conducted power levels for each operational mode. Device approval requires maximum localized values to stay below regional statutory thresholds under maximum output power conditions. Final reports document exact spatial coordinates of maximum absorption nodes relative to product housing geometry.
