Product Info
MORLAB
Shenzhen Morlab Communications Technology Co., Ltd.
FL1-3, Building A, FeiYang Science Park, No.8 LongChang Road,
Block67, BaoAn District, ShenZhen , GuangDong Province, P. R. China
Tel: 86-755-36698555 Fax: 86-755-36698525
Http://www.morlab.cn E-mail: service@morlab.cn
REPORT No.：SZ21070039S02
Page 8 of 53
3. Specific Absorption Rate (SAR)
3.1. Introduction
SAR is related to the rate at which energy is absorbed per unit mass in an object exposed to a radio
field. The SAR distribution in a biological body is complicated and is usually carried out by
experimental techniques or numerical modeling. The standard recommends limits for two tiers of
groups, occupational or controlled and general population or uncontrolled, based on a person’s
awareness and ability to exercise control over his or her exposure. In general, occupational or
controlled exposure limits are Middle than the limits for general population or uncontrolled.
3.2. SAR Definition
The SAR definition is the time derivative (rate) of the incremental energy (dW) absorbed
by(dissipated in) an incremental mass (dm) contained in a volume element (dv) of a given density.
(ρ). The equation description is as below:
SAR is expressed in units of Watts per kilogram (W/kg).
SAR measurement can be either related to the temperature elevation in tissue by,
Where C is the specific head capacity, δT is the temperature rise and δt the exposure duration, or
related to the electrical field in the tissue by
|
|
Where σ is the conductivity of the tissue, ρ is the mass density of the tissue and
|
E
|
is the
rmselectrical field strength.
However for evaluating SAR of low power transmitter, electrical field measurement is typically
applied.