Magnetic Immunity Level Setting

IEC 61000-4-39 Magnetic Measurements

IEC 60601-1-2 Magnetic Level Setting

RS 101 Magnetic Immunity Level Setting

ISO 11452-8 Magnetic Immunity Level Setting

When using a loop sensor to set your test levels sometimes, it is not always straightforward how to apply the calibration/correction provided by manufacturers/calibration houses. This article shows the calculations used with examples. My preferable method would be to use dB logarithmic values, as I think it is easier than linear.

1.    Correction is given in dBOhm 

dBµA = dBµV + dBOhm

            dBµA - dBOhm = dBuV ç what is measured on Spectrum Analyzer

            A test level of 6.5A/m at 13.56 MHz and correction is 18.63 dBOhms

                        dBµA = 20⋅log10(A)+120

                         dBµA = 20⋅log10(6.5)+120

                        6.5 A/m = 136.3 dBµA 

                        136.3 dBµA - 18.63 dBOhm = 117.67 dBµV level to look for on the analyzer

2.    Correction is given in dB(pT/µV)

dBpT = dBµV + dBpT/µV

            dBpT - dBpT/µV = dBuV ç what is measured on Spectrum Analyzer

A test level of 6.5A/m at 13.56 MHz, Antenna Correction 19.98 dB(pT/µV)

                        dBpT = 20⋅log10(A)+122

                        138.3 = 20⋅log10(6.5)+122

                        6.5 A/m = 138.3 dBpT

                        138.3 dBpT - 19.98 dB(pT/µV) = 118.41 dBµV level to look for on the analyzer

dBOhm may also be written as dB(µA/dBµV) or “Conversion dBµV to dBµA”. In this case, equation 1. will work.

For unit conversions, please check out our online calculators.