STEPS for Computing SAR

• Step 1: Determine the center frequency


• Step 2: Determine the Skin depth


• Step 3: Compute/measure the Power density


• Step 4: Estimate the tissue Electric field intensity


• Step 5: Compute the SAR

Permittivity:

Permeability:

Speed of electromagnetic wave:

Example

Considering a WiFi router, the brain SAR for growing male/female infant till 36 months (WiFi radio being (5cm away) 2.5 GHz band operating at frequencies 2400MHz and 2500MHz for lower and upper frequencies respectively. Hence from this we have center frequency as fc = 2450 MHz. At this frequency we have the tissues electromagnetic properties as given in SAR Tables below with peak transmit power of 100mW for OFDM technology.