RF exposure report

FCC ID: 2AKIT-DJT11LM

RF Exposure Info

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FCCID_3236977

RF Exposure Evaluation For FCC ID: 2AKIT-DJT11LM

Refer user manual this device is a Vibration Sensor, 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)


                                                  Zigbee
          Mode                     Low channel              Middle channel           High channel
   Peak Power (dBm)                   11.09                      11.61                   11.65
  Note: This report listed the maximal case peak power value, please refer to RF test report for
  more details.


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)
     Zigbee            11.65            1.5       20.65         20           1       0.004        Pass


Note:
1. The Vibration Sensor work frequency range used is 2400 MHz ~ 2483.5 MHz, the result close to
   the limit by the above formula so, we select 2480MHz to calculate the exclusion power threshold.
2. More power list please refer to RF test report.



Document Created: 2019-09-29 19:41:25
Document Modified: 2019-09-29 19:41:25

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