Calculating Total Exposure Ratios for Co Located Transmitters in Handheld Equipment
Multi-radio handheld exposure compliance requires summing normalized SAR values across concurrent transmitters to verify the total exposure ratio stays below unity.
Simultaneous Transmission Analysis
Meaning
Electromagnetic safety assessment evaluates the combined exposure of multiple co-located transmitters operating at the same time. Performing simultaneous transmission analysis ensures that a multi-radio device does not exceed maximum permissible exposure or Specific Absorption Rate limits. This assessment is required when a product integrates multiple wireless modules, such as Wi-Fi, Bluetooth, and cellular antennas, in close physical proximity.
The analysis applies to all combinations of transmitters that can broadcast concurrently under normal operating conditions, establishing the cumulative exposure profile for the complete assembly.
Exposure Calculation
Mathematical summation combines individual radiation values to determine the cumulative absorption rate. When executing simultaneous transmission analysis, engineers use specific formulas to calculate the sum of the individual SAR ratios. This step verifies that the combined fields remain below the regulatory limit.
Test Reduction
Exclusion criteria allow developers to skip complex multi-transmitter scans when the individual fields are far apart or have low power. By utilizing simultaneous transmission analysis, engineers can prove that certain antenna combinations are naturally isolated, which saves substantial lab testing time. This reduction streamlines the approval timeline for smart devices.
Regulatory Compliance
Official certification ensures that wireless devices are safe for consumer use before entering the market. Completing a simultaneous transmission analysis is a standard part of FCC and ISED approval processes for connected devices. This documented analysis is included in the final filing package submitted to the certification body.