System Description

TEL : [phone]
Page
21 of 173
FAX : [phone]
Issued Date
:
Feb. 14, 2020
Form version: 181113
FCC SAR TEST REPORT
Report No. : FA9O2119
5. Specific Absorption Rate (SAR)
5.1 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/controlled and general
population/uncontrolled, based on a person’s awareness and ability to exercise control over his or her exposure. In
general, occupational/controlled exposure limits are higher than the limits for general population/uncontrolled.
5.2 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 =
𝐝
𝐝𝐭
(
𝐝𝐖
𝐝𝐦
)
=
𝐝
𝐝𝐭
(
𝐝𝐖
𝛒𝐝𝐯
)
SAR is expressed in units of Watts per kilogram (W/kg)
𝐒𝐀𝐑 =
𝛔
|
𝐄
|
𝟐
𝛒
Where: σ is the conductivity of the tissue, ρ is the mass density of the tissue and E is the RMS electrical field strength.