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Standards for Exposure to Electromagnetic Fields
b) Measurement and analysis to demonstrate compliance with the basic limits
For inductive systems up to 50 MHz, an approximation formula for the H-field and the excited surface current in human
tissue through the loop antennas applies. The conductivity of the tissue is also approximated.
For systems in the frequency range 100 kHz to 10 GHz, one assumes a localised SAR value.
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Localised SAR above 10 g body weight is taken into account
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The limit is 2 W/kg, which is equivalent to 20 mW per 10 g body weight
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All conducted power is delivered to this 10 g body weight
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Any device that delivers less than 20 mW conducted power is considered compliant
c) Numerical modelling to demonstrate compliance with the basic limits
In numerical modelling, the properties of a human model are applied and evaluated using a simulation principle and
techniques.The following values are defined as properties of the human model:
Size 1.76 m ± 5%
Weight 73 kg ± 5%
The representation of the inhomogeneous human structure takes place:
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with realistic body permeability (frequency-dependent)
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with volume pixel (voxel) resolution smaller than 10 mm
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for the voxel with the highest SAR when more than one type of tissue is present in a single voxel.
It is acceptable that the local exposure models only a certain part of the body.
The simulation principles and techniques are carried out with the finite element method (FEM) in the frequency domain
or in the time domain with the finite difference method (FDTD). Other techniques are also permissible if they lead to the
same results.
SAR =
σE
2
ρ
E – Electric field strength in the body
σ – Electrical conductivity of the body
ρ – Density of the body
