Re: SAR CORRECTION FOR MEASURED CONDUCTIVITY AND RELATIVE PERMITTIVITY BASED ON IEC 62209-2 STANDARD
Industry Canada's RSS-102 - RF exposure compliance of radiocommunication apparatus (All frequency Bands) incorporates by reference the International Electrotechnical Commission (IEC) 62209-2 Human Exposure to Radio Frequency Fields from Hand Held and Body-mounted Wireless Communication Devices - Human Models, Instrumentation, and Procedures - Part 2: Procedure to determine the specific absorption rate (SAR) for wireless communication devices used in close proximity to the human body (frequency range of 30MHz to 6GHz).
Section 6.1.1 of IEC 62209-2 Ed. 1 states:
The measured conductivity and relative permittivity shall be within 10% of the target values. The measured SAR results shall be corrected using the procedures of Annex F. If the correction ΔSAR has a negative sign, the measured SAR results shall not be corrected.
In Section 6.1.1 of IEC 62209-2, there is currently an error regarding the sign for the correction of SAR. It should read:
If the correction ΔSAR has a positive sign, the measured SAR results shall not be corrected.
The ΔSAR refers to the percent change in SAR relative to the percent change in dielectric properties versus the target values. A negative ΔSAR would translate to a lower measured SAR value than what would be measured if using dielectric properties equal to the target values. A positive ΔSAR would translate to a higher measured SAR value than what would be measured if using dielectric properties equal to the target values. SAR correction shall not be made when the ΔSAR has a positive sign to provide a conservative SAR value. The SAR is only corrected when ΔSAR has a negative sign.
The correction is implemented using Equation 1. The ΔSAR must first be inverted (- to +) when implementing the correction as given in the following example:
With a measured SAR of 1.00 W/Kg and a ΔSAR of -6%, the corrected SAR would be:
Corrected SAR = Measured SAR * ((100 +(ΔSAR × -1)); (Equation 1)
Corrected SAR = 1.00 W/Kg *((100 +6)/100) = 1.06 W/Kg
In addition, this notice provides clarification pertaining to Industry Canada’s latest requirements on the SAR correction when the measured conductivity and relative permittivity deviate from the target values.
If the dielectric properties of the tissue simulating liquid are equal or less than 5% of the target values, one of the following actions shall be undertaken:
i) the measured uncertainty is added to the uncertainty budget, or
ii) the SAR value is corrected and the applicable uncertainty contributor associated with the correction formula is added to the uncertainty budget using the procedure of Annex F of IEC 62209-2.
However, if the dielectric properties of the tissue simulating liquid are above 5% but equal or less than 10% of the target values, the SAR value shall be corrected for the deviation in the dielectric properties using the procedures of Annex F of IEC 62209-2 and the uncertainty of the correction formula shall be added to the uncertainty budget.
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