Modular Wireless Certification Class Changes under FCC Rules
FCC modular class changes require Class I audit logs for minor zero-increase emissions shifts and Class II filings for higher gain, host SAR, or altered spurious profiles.
SAR to Peak Location Separation Ratio
Meaning
Calculated values used to evaluate the potential for radio frequency exposure when multiple transmitters operate simultaneously near the human body are checked against safety limits. The SAR to Peak Location Separation Ratio determines if a device requires simultaneous transmission testing or can be exempted based on the distance between peak energy locations. This calculation is restricted to devices used within twenty centimetres of the body.
Engineers use this ratio to simplify the certification of multi-radio devices.
Exemption Threshold
Regulatory agencies define a numeric threshold above which physical co-transmission testing must be performed. If the SAR to Peak Location Separation Ratio is below this value, the device is exempt from the complex simultaneous SAR tests. This exemption saves significant testing time and cost.
Mathematical Formula
A mathematical formula determines the ratio based on the peak specific absorption rate values and the physical distance between those peaks. To find the SAR to Peak Location Separation Ratio, the sum of the peak values is scaled by the distance raised to a fractional power. This formula is specified in international testing standards.
Product Application
Smart devices with multiple antennas such as cellular phones and tablets are evaluated using this metric. By applying the SAR to Peak Location Separation Ratio, developers can optimize the placement of the antennas to minimize joint exposure. This optimization ensures that the final product passes safety audits.