QPE6105A
FCC Certification Guide
– Bluetooth™ Low Energy Mode
Subject to change without notice | All rights reserved. © 2022-2023 Qorvo, Inc.
GP335_UM_20021 Version 1.00
Page
6
of
15
®
3.7
Radio Frequency Radiation Exposure Evaluation
The applicable FCC sections are:
•
CFR 47 Part 2 - § 2.1091 - Radiofrequency radiation exposure evaluation: mobile devices.
•
CFR 47 Part 1 - § 1.1310 - Radiofrequency radiation exposure limits.
The DUT is classified as a
mobile device
, so the applicable distance for the radiation exposure evaluation
is 20 cm (0.2 m) and the limit is 1 mW/cm
2
. Please find below an example on calculating the power density.
The default Tx power level is 10 dBm, the peak antenna gain is -3 dBi.
Antenna pattern, see ref [4]
𝑃
𝑇𝑥
= 𝑇𝑥 𝑝𝑜𝑤𝑒𝑟 𝑎𝑡 𝐴𝑛𝑡𝑒𝑛𝑛𝑎 = 10
dBm
𝐺
𝑎
= 𝐴𝑛𝑡𝑒𝑛𝑛𝑎 𝑔𝑎𝑖𝑛 = −3
dBi
(equal for both antennas)
𝑑 = 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 = 0.2
m
𝐸𝐼𝑅𝑃
[𝑑𝐵𝑚]
= 𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝐼𝑠𝑜𝑡𝑟𝑜𝑝𝑖𝑐 𝑅𝑎𝑑𝑖𝑎𝑡𝑒𝑑 𝑃𝑜𝑤𝑒𝑟 = 𝑃
𝑡𝑥
+ 𝐺
𝑎
= 7 dBm
𝐸𝐼𝑅𝑃
[𝑊]
= 𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝐼𝑠𝑜𝑡𝑟𝑜𝑝𝑖𝑐 𝑅𝑎𝑑𝑖𝑎𝑡𝑒𝑑 𝑃𝑜𝑤𝑒𝑟 = 10
𝐸𝐼𝑅𝑃
[𝑑𝐵𝑚]
−30
10
= 0.005 W
𝑃𝐷
[𝑊 𝑚
2
]
⁄
= 𝑃𝑜𝑤𝑒𝑟 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =
𝐸𝐼𝑅𝑃
[𝑊]
4. π. 𝑑
2
= 0.01
W/m
2
𝑃𝐷
[𝑚𝑊 𝑐𝑚
2
]
⁄
= 𝑃𝑜𝑤𝑒𝑟 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑃𝐷
[𝑊 𝑚
2
]
⁄
×
1000
10000
=
𝟎. 𝟎𝟎𝟏 𝐦𝐖/𝐜𝐦
𝟐
@ 0.2 m distance
Note: limit of Power Density: 1 mW/cm
2
.