Simultaneous Transmit SAR Evaluation Thresholds in Portable Radio Systems
Simultaneous SAR evaluations require summing standalone SAR or estimated values to prove combined exposure remains below regulatory limits.
Phantom Model
Meaning
Testing vessels shaped like human heads or bodies hold formulated liquids that mimic the dielectric properties of biological tissue during exposure scans. Scanners use a phantom model to establish a repeatable testing environment for cellular devices and wearable electronics. This structure provides a standardized boundary that ensures different laboratories get the same results when testing the same device.
Its use is required by international testing guidelines to ensure regulatory compliance before products go to market.
Material Selection
The outer container is molded from a low-loss plastic that does not interfere with the electromagnetic fields. Inside the container, a mix of water, salt, and organic compounds creates the correct permittivity and conductivity for the target frequency.
Measurement Accuracy
Standardized models remove the variability of testing on live human subjects, which would produce inconsistent results. Technicians mount the device against the outer surface of the phantom model in a highly reproducible position. The scanning probe is then lowered into the liquid through an opening to measure the internal field strength.
This configuration ensures that the recorded data reflects a worst-case exposure scenario.
Shell Geometry
Specific shapes model different parts of the human anatomy to represent average adult dimensions. Flat sections simulate the torso for body-worn testing, while contoured surfaces model the ear and cheek regions for handset testing. Each structural region must maintain a precise wall thickness, usually two millimeters, to prevent distortion of the measured field.
Verification tests are conducted periodically to confirm that the shell has not deformed over time.