MPE

FCC ID: 2AKIT-ZHWG11LM

RF Exposure Info

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FCCID_3623063

RF Exposure Evaluation For FCC ID: 2AKIT-ZHWG11LM

Refer user manual this device is a Hub, and this device was designed used in Mobile devices that the
minimum distance between human’s body is 20cm. Based on the 47CFR 2.1091, this device belongs
to Mobile device. The definition of the category as following:

Mobile Derives:
CFR Title 47 §2.1091(b)
(b) For purposes of this section, a mobile device is defined as a transmitting device designed to be
used in other than fixed locations and to generally be used in such a way that a separation distance
of at least 20 centimeters is normally maintained between the transmitter’s radiating structure(s) and
the body of the user or nearby persons.
FCC KDB 447498 D01 General RF Exposure Guidance v06 Limit

Devices operating in standalone mobile exposure conditions may contain a single transmitter or
multiple transmitters that do not transmit simultaneously. A minimum test separation distance ≥ 20 cm
is required between the antenna and radiating structures of the device and nearby persons to apply
mobile device exposure limits. The distance must be fully supported by the operating and installation
configurations of the transmitter and its antenna(s), according to the source-based time-averaged
maximum power requirements of § 2.1091(d)(2). In cases where cable losses or other attenuations
are applied to determine compliance, the most conservative operating configurations and exposure
conditions must be evaluated. The minimum test separation distance required for a device to comply
with mobile exposure conditions must be clearly identified in the installation and operating instructions,
for all installation and exposure conditions, to enable users and installers to comply with RF exposure
requirements. For mobile devices that have the potential to operate in portable device exposure
conditions, similar to the configurations described in § 2.1091(d)(4), a KDB inquiry is required to
determine the SAR test requirements for demonstrating compliance.

When the categorical exclusion provision of § 2.1091(c) applies, the minimum test separation distance
may be estimated, when applicable, by simple calculations according to plane-wave equivalent
conditions, to ensure the transmitter and its antenna(s) can operate in manners that meet or exceed
the estimated distance. The source-based time-averaged maximum radiated power, according to the
maximum antenna gain, must be applied to calculate the field strength and power density required to
establish the minimum test separation distance. When the estimated test separation distance
becomes overly conservative and does not support compliance, MPE measurement or computational
modeling may be used to determine the required minimum separation distance.


According to FCC Part 1.1307, systems operating under the provisions of this section shall be
operated in a manner the ensures that the public is not exposed to radio frequency energy level in
excess of the commission’s guidelines.
                         Limits for General Population/ Uncontrolled Exposure
     Frequency Range              Electric Field         Magnetic Field             Power Density
          (MHz)                 Strength(E)(V/m)        Strength (H)(A/m)            (S)(mW/cm2)
            0.3-1.34                  614                       1.63                    (100)*
            1.34-30                  824/f                      2.19/f                 (180/f2)*
            30-300                    27.5                      0.073                     0.2
         300-1500                                                                       f/1500
       1500-100,000                                                                       1.0
MPE calculation formula




Where:
S = power density
P = output power (mW)
G = power gain of the antenna in the direction of interest relative to an isotropic radiator
R = Separation distance between radiator and human body (cm)

Test data
                                                WIFI 2.4G
              Mode                  802.11b           802.11g             802.11n-20      802.11n-40
      Peak Power (dBm)               18.87              18.82               18.61               19.16
                                                 Zigbee
              Mode                   Low Channel            Middle Channel             High Channel
      Peak Power (dBm)                  24.04                     24.30                   23.75
  Note: This report listed the worst case peak power value, please refer to RF test report for more
  details.


Turn-up power
              Mode                                    Peak Power Range (dBm)
             802.11b                                         18.10-19.40
             802.11g                                         18.00-19.30
            802.11n-20                                       18.00-19.10
            802.11n-40                                       17.30-19.70
             Zigbee                                          23.20-24.80


Test result
                     Maximum       Antenna                           Limit of
                                                Total                           Power
    Evolution       peak output      Gain               Distance      Power
                                               Power                           Density        Verdict
     mode             power        (typical)              (cm)       Density
                                               (mw)                           (mW/cm²)
                     (dBm)           (dBi)                          (mW/cm²)
    802.11n-40         19.70          2.0      147.91       20          1          0.03       Pass
      Zigbee           24.80          1.5      426.58       20          1          0.08       Pass


Collocated Power Density Calculation


                                                             Σ(Power Density / Limit)
  Evolution                                   Power
                   Frequency(MHz)                                      of                   Verdict
   mode                                     Density/Limit
                                                              WIFI 2.4GHz+ Zigbee


 2.4G WIFI       2412MHz ~ 2462MHz              0.03                                         Pass
                                                                       0.11
   Zigbee        2400MHz ~ 2483.5MHz            0.08                                         Pass


Note:
1. Σ(Power Density / Limit): This is a summation of [(power density for each transmitter/ antenna
   included in the simultaneous transmission)/ (corresponding MPE limit)], for WLAN 2.4GHz+
   Zigbee.
2. the 2.4GHz and Zigbee can transmit simultaneously, the formula of calculated the MPE is
   CPD1 / LPD1 + CPD2 / LPD2 + ……etc. <
   CPD = Calculation power density
   LPD = Limit of power density
3. The worst-case situation is 0.11, which is less than “1”. This confirmed that the device comply with
   FCC 1.1310 MPE limit.
4. The Hub work frequency range used is 2400 MHz ~ 2483.5 MHz, the result close to the limit by
   the above formula,
5. More power list please refer to RF test report.

Conclusion:
According to 47 CFR §2.1091, the RF exposure analysis concludes that the RF Exposure is FCC
compliant.



Document Created: 2017-09-27 15:15:25
Document Modified: 2017-09-27 15:15:25

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