RF Exposure Info

FCC ID: LDKSBSPA525G01

RF Exposure Info

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FCCID_1284730

                      RF EXPOSURE REPORT

                REPORT NO.:    SA970909H06B
                 MODEL NO.:    SPA525G, SPA525G2


                ACCORDING:     FCC Guidelines for Human Exposure
                               IEEE C95.1


                 APPLICANT: Cisco Systems Inc

                   ADDRESS: 170 W Tasman Dr, San Jose, CA95134, USA




                  ISSUED BY:   Bureau Veritas Consumer Products Services (H.K.)
                               Ltd., Taoyuan Branch
            LAB LOCATION: No. 81-1, Lu Liao Keng, 9th Ling,Wu Lung Tsuen,
                          Chiung Lin Hsiang, Hsin Chu Hsien 307, Taiwan




Report No.: SA970909H06B                  1                  Report Format Version 3.0.1
Reference No.: 990406E01


                           RF Exposure Measurement
1. Introduction

In this document, we try to prove the safety of radiation harmfulness to the human body
for our product. The limit for Maximum Permissible Exposure (MPE) specified in FCC
1.1310 is followed. The Gain of the antenna used in this product is measured in a Fully
Anechoic Chamber (FAC) calibrated for antenna measurement in our lab, and also the
maximum total power input to the antenna is measured. Through the Friis transmission
formula and the maximum gain of the antenna, we can calculate the distance, away
from the product, where the limit of MPE is reached.
Although the Friis transmission formula is a far field assumption, the calculated result of
that is an over-prediction for near field power density. We will take that as the worst
case to specify the safety range.

2. RF Exposure Limit
According to FCC 1.1310: The criteria listed in the following table shall be used to
evaluate the environmental impact of human exposure to radio-frequency (RF) radiation
as specified in 1.1307(b)

LIMITS FOR MAXIMUM PERMISSIBLE EXPOSURE (MPE)

   Frequency          Electric Field   Magnetic Field   Power Density        Average Time
     Range           Strength (V/m)    Strength (A/m)     (mW/cm2)             (minutes)
     (MHz)
                    (A)Limits For Occupational / Control Exposures
    300-1500                …               …               F/300                   6
 1500-100,000               …               …                  5                    6
              (B)Limits For General Population / Uncontrolled Exposure
    300-1500                …               …               F/1500                  30
 1500-100,000               …               …                 1.0                   30
F = Frequency in MHz




Report No.: SA970909H06B                     2                      Report Format Version 3.0.1
Reference No.: 990406E01


3. Friis Formula


Friis transmission formula : Pd = (Pout*G) / (4*pi*r2)


where
Pd = power density in mW/cm2
Pout = output power to antenna in mW
G = gain of antenna in linear scale
Pi = 3.1416
R = distance between observation point and center of the radiator in cm


Pd is the limit of MPE, 1 mW/cm2. If we know the maximum Gain of the antenna and the
total power input to the antenna, through the calculation, we will know the MPE value at
distance 20cm.

Ref. : David K. Cheng, Field and Wave Electromagnetics, Second Edition,
      Page 640, Eq. (11-133).



4. EUT Operating condition
The software provided by Manufacturer enabled the EUT to transmit and receive data at
lowest, middle and highest channel individually.



5. Classification
The antenna of this product, under normal use condition, is at least 20cm away from the
body of the user. Warning statement to the user for keeping at least 20cm or more
separation distance with the antenna should be included in users manual. So, this
device is classified as Mobile Device.




Report No.: SA970909H06B                     3                  Report Format Version 3.0.1
Reference No.: 990406E01


6. TEST RESULTS
6.1 Antenna Gain
The maximum Gain measured in Fully Anechoic Chamber is 2.7dBi or 1.862087
(numeric) for WLAN and 3.5dBi or 2.238721 (numeric) for Bluetooth.

6.2 Output Power Into Antenna & RF Exposure value at distance 20cm:
 802.11b:
                   Channel                                          Limit of
                              Output Power to   Power Density
   Channel        Frequency                                      Power Density
                              Antenna (mW)        (mW/cm2)
                    (MHz)                                          (mW/cm2)
      1              2412          89.1            0.033              1.0
      6              2437          85.1            0.032              1.0
      11             2462          89.1            0.033              1.0

 802.11g:
                   Channel                                          Limit of
                              Output Power to   Power Density
   Channel        Frequency                                      Power Density
                              Antenna (mW)        (mW/cm2)
                    (MHz)                                          (mW/cm2)
      1              2412         173.8            0.064              1.0
      6              2437         169.8            0.063              1.0
      11             2462         177.8            0.066              1.0

 For Bluetooth GPSK:
                   Channel                                          Limit of
                              Output Power to   Power Density
   Channel        Frequency                                      Power Density
                              Antenna (mW)        (mW/cm2)
                    (MHz)                                          (mW/cm2)
       0             2402           1.3            0.001              1.0
      39             2441           1.4            0.001              1.0
      78             2480           2.0            0.001              1.0

 For Bluetooth 8DPSK:
                   Channel                                          Limit of
                              Output Power to   Power Density
   Channel        Frequency                                      Power Density
                              Antenna (mW)        (mW/cm2)
                    (MHz)                                          (mW/cm2)
       0             2402           0.8            0.000              1.0
      39             2441           0.9            0.000              1.0
      78             2480           1.2            0.001              1.0




Report No.: SA970909H06B                  4                Report Format Version 3.0.1
Reference No.: 990406E01


CONCLUSION:
Both of the WLAN and Bluetooth can transmit simultaneously, the formula of calculated
the MPE is:


CPD1 / LPD1 + CPD2 / LPD2 + ……etc. < 1
CPD = Calculation power density
LPD = Limit of power density


Therefore, the worst-case situation is 0.066 / 1 + 0.001 / 1 = 0.067, which is less than
“1”. This confirmed that the device comply with FCC 1.1310 MPE limit.



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Report No.: SA970909H06B                     5                    Report Format Version 3.0.1
Reference No.: 990406E01



Document Created: 2010-04-28 17:17:41
Document Modified: 2010-04-28 17:17:41

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