RF Exposure evaluation

FCC ID: 2AR7Q-E01003

RF Exposure Info

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FCCID_4347831

                 Maximum Permissible Exposure Evaluation


An estimation of MPE in this application for product is used to ensure if it complies to the

rules of the standard in the regulation list above.

Maximum permissible exposure (MPE) refers to the RF energy that is acceptable for

human exposure. It is broken down into two categories, Occupational/controlled and

General population/uncontrolled.

Occupational/controlled limits apply in situations in which persons are exposed as a

consequence of their employment provided those persons are fully aware of the potential

for   exposure    and    can    exercise     control     over   their   exposure.   Limits   for

occupational/controlled exposure also apply in situations when an individual is transient

through a location where occupational/controlled limits apply provided he or she is made

aware of the potential for exposure.

General population/uncontrolled exposures apply in situations in which the general public

may be exposed, or in which persons that are exposed as a consequence of their

employment may not be fully aware of the potential for exposure or can not exercise

control over their exposure.

We analysis if it comply with the limits for General population/uncontrolled exposure. The

FCC’s MPE limits for field strength and power density are given in 47CFR 1.1310(Table

below).These limits are generally based on recommended exposure guidelines published

by the National Council on Radiation Protection and Measurements (NCRP), and also

partly based on guidelines recommended by the American National Standards Institute

(ANSI) in Section 4.1 of ANSI/IEEE C95.1.




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                Table: Limits For Maximum Permissible Exposure (MPE)

                     (A) Limits for Occupational/controlled Exposure

                                                              Power         Averaging Time
 Frequency       Electric Field        Magnetic Field
                                                              Density      (minute)|E|2,|H|2 or
Range(MHz)     Strength(E)(V/m)       Strength(H)(A/m)
                                                           (S)(mW/cm2)              S

   0.3-3.0             614                 1.63               (100)*               6

   3.0-30             1842/f               4.89/f            (900/f2)*             6

   30-300              61.4                0.163                1.0                6

  300-1500              --                   --                f/300               6

1500-100,000            --                   --                  5                 6

               (B) Limits for General Population/uncontrolled Exposure

                                                              Power         Averaging Time
 Frequency       Electric Field        Magnetic Field
                                                              Density      (minute)|E|2,|H|2 or
Range(MHz)     Strength(E)(V/m)       Strength(H)(A/m)
                                                           (S)(mW/cm2)              S

  0.3-1.34             614                 1.63               (100)*               30

   1.34-30            824/f                2.19/f             (180/f)*             30

   30-300              27.5                0.073                0.2                30

  300-1500              /                    /                f/1500               30

1500-100,000            /                    /                  1.0                30

f=frequency in MHz                                       *Plane-wave equivalent power density

A rough estimation of the expected exposure in power flux density on a given point can be

made with the following equation:


                               P*G
                         S=
                              4π*R2

Where:

    S = power density

    P = power input to the antenna

    G = numeric gain of the antenna in the direction of interest relative to an isotropic

radiator



                                           Page 2 of 3


              R= distance to the centre of radiation of the antenna

              EIRP = P*G



        The antenna of the product, under normal use condition is at least 20 cm away

        from the body of the user. Warning statement to the user for keeping at least

        20cm separation distance and the prohibition of operating to a person has been

        printed on the user’s manual. Therefore, the S of the device is calculated with

        R=20cm, and if it is below the limit S, then we can conclude the device complies

        with the rules.



        The worst case (refer to report FCC18120074A-U-NII) is below:
        For 2.4G Wi-Fi:
        Antenna Gain: 2.65dBi

TYPE                                  Max.
                    Max.
                                    Conducted             R             S       MPE Limit
                 Conducted                                                                  Conclusion
                                       Power             (cm)      (mW/cm2)     (mW/cm2)
                Power (dBm)
                                      (mW)
Antenna:1           19.97              99.31                  20      0.03637
Antenna:2           19.59              90.99                  20      0.03332
Antenna 1 +                                                                        1.00      PASS
Antenna 2           22.79             190.11                  20      0.06962


        Note:*- based on the maximum tune-up tolerance limit declared by manufacturer.

       0.06962<1.00

       So the SAR report is not required.




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Document Created: 2019-03-25 10:16:24
Document Modified: 2019-03-25 10:16:24

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