Managing Multi-Market Radio Frequency Exposure Filings for Handheld Transceivers
Handheld exposure filings demand unified 1g and 10g spatial SAR test plans, tight proximity sensor power backoff logic, and deterministic firmware controls.
Simultaneous Transmission Ratio
Meaning
Numerical sum calculations determine whether a multi-transmitter wireless device requires expensive and time-consuming co-located specific absorption rate measurements. Simultaneous transmission ratio represents the ratio of the individual specific absorption rates of the co-located transmitters to their spatial separation distance. If this calculated ratio falls below a specific regulatory limit, the device is exempt from further empirical multi-transmitter testing.
Product designers use this mathematical shortcut to demonstrate compliance for multi-radio devices without having to configure complex, concurrent transmission test setups in the laboratory.
Numeric Evaluation
The calculation combines the maximum measured specific absorption rate of each transmitter with the physical distance between their peak locations. A low simultaneous transmission ratio indicates that the hot spots generated by the separate antennas do not overlap. This lack of overlap prevents localized cumulative exposure.
Exclusion Calculation
Regulatory bodies define the mathematical formula used to determine the exclusion threshold. If the simultaneous transmission ratio is less than the specified limit, the filing can proceed without multi-band laboratory scans. This exemption saves significant engineering hours.
Product Design
Antenna placement is optimized during the early layout phase to maximize the physical separation between transmitters. This spacing helps achieve a low simultaneous transmission ratio on the finished board. Proper placement minimizes the risk of late-stage redesigns.