RF Exposure Info

FCC ID: BCGA1876

RF Exposure Info

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FCCID_4045740

                                                                                                           FCC Test Results

          FCC ID:                                     BCGA1876
            Date:                           September 12-14, 2018
     Test Method:                             Per FCC KDB Inquiry
    iPad EUT S/N:                                DLXWX007KNPN
       Pencil S/N                               GQXXC1W2JKM9


RF Exposure Measurements of Wireless Charging
Transmitter Per FCC KDB Inquiry

Purpose: The purpose of this test report is to determine the worst-case H-Field and E-Field levels
emitted by the wireless charging transmitter of the EUT Host to the pencil per FCC KDB Inquiry to
determine qualification for SAR test exclusion.
Wireless Charging Maximum Output Power from Host: 7.44 W
Wireless Charging Operating Frequency: 127.7 kHz
Test results reported herein relate only to the item(s) tested.




Note: This revised Test Report (S/N: 1C1806050010-12-R2.BCG) supersedes and replaces the previously issued test report on the same
subject device for the same type of testing as indicated. Please discard or destroy the previously issued test report(s) and dispose of it
accordingly.


© 2018 PCTEST LAB                                                 Page 1 of 8              Test Report S/N: 1C1806050010-12-R2.BCG


                                                                                      FCC Test Results

Test Equipment
 Manufacturer      Model          Description                     Cal. Date      Cal. Due Date      Serial Number
 Narda             ELT-400        Exposure Level Tester           5/30/2017      5/30/2019          N-0727
 Narda             2300-90.20     B-Field Probe                   12/14/2017     12/14/2019         C-0271
 Narda             ELT-400        Exposure Level Tester           2/27/2017      2/27/2019          N-0701
 Narda             2300-90.20     B-Field Probe                   3/21/2017      3/21/2019          C-0232
 Narda             EHP-200A       E and H Field Probe             6/22/2017      6/22/2019          170WX70613
                                  Analyzer



Definitions
   •     Optimal Placement (Max Coupling) = Optimal pencil location as positioned by the magnets that
         hold the pencil in place.
   •     Min Coupling = Misalignment as described in the KDB inquiry.
   •     Charging Profiles:

                     Charge Rate           Battery State of Charge         Charge Duration in Min
                        10.0 C                      0 - 4%                        0m 12s
                        3.0 C                       4 - 12%                        2m 0s
                        2.5 C                      12 - 85%                       22m 0s
                     1 C (Trickle)                85 - 100%                       20m 0s



X, Y, Z Axis Description




                                       Figure 1 Pencil Alignment X, Y, Z Axis

   •     For the X axis, the positive direction is towards the tail of the pencil, and the negative direction is
         towards the writing tip of the pencil.
   •     For the Y axis, the negative direction is increasing air gap
   •     For the Z axis, the positive direction is towards the front screen of device, and the negative
         direction is towards the back shell of the device.




© 2018 PCTEST LAB                                   Page 2 of 8            Test Report S/N: 1C1806050010-12-R2.BCG


                                                                                 FCC Test Results
Verification of H-Field Control (HFC) Algorithm
   •   Tx coil current (ITX) and Rx current (IRECT) and efficiency are used to define the hard thresholds
       used in H-Field control algorithm. H-field control algorithm will always limit the Max H-fields
       below worst-case value.
   •   Measurement procedure was performed per FCC KDB Inquiry.
   •   Data in the following table were recorded from real time streaming command prompt output that
       monitors the current and efficiency of the EUT Host’s wireless charging function with pencil.

                                                                        Charging
              Measurement Cases                     Pencil alignment                  ITx (A)   IRECT (A)
                                                                        condition

                                                             0             10C         0.91       0.22

                                                             0              3C         0.52       0.11
       Optimal Alignment (Max Coupling)
                                                             0             2.5C        0.51       0.09

                                                             0              1C         0.46       0.06


                                Min Coupling,         ∆z = -2.8 mm         10C         1.54       0.22
                                shifting pencil
                                towards back          ∆z = -3.0 mm          3C         0.93       0.11
                              (-Z) until charging
                                throttles, then       ∆z = -3.2 mm         2.5C        1.00       0.09
                              move back by 0.2
                                      mm              ∆z = -3.2 mm          1C         0.88       0.06

                                                       ∆z = +4 mm          10C         1.54       0.22
                                Min Coupling,
                                shifting pencil
                               towards Display        ∆z = +4.4 mm          3C         0.93       0.11
                              (+Z) until charging
                                throttles, then       ∆z = +4.6 mm         2.5C        1.01       0.09
                               move back by 0.2
                                      mm
                                                      ∆z = +4.8 mm          1C         0.88       0.06

                                                      ∆y = -1.5 mm         10C         1.54       0.22
                               Min Coupling,
                                   shifting
                              pencil away from        ∆y = -1.7 mm          3C         0.96       0.11
                                iPad(-Y) until
                             charging throttles,      ∆y = -1.7 mm         2.5C        0.96       0.09
                             then move back by
                                   0.2 mm
                                                      ∆y = -2.1 mm          1C         0.91       0.06



© 2018 PCTEST LAB                              Page 3 of 8          Test Report S/N: 1C1806050010-12-R2.BCG


                                                                      FCC Test Results
                                           ∆x = +3.4 mm         10C         1.45      0.22
                      Min Coupling,
                      shifting pencil
                     upward in lateral     ∆x = +3.8 mm          3C         0.95      0.11
                      plane(+X) until
                    charging throttles,     ∆x = +4 mm          2.5C        0.99      0.09
                    then move back by
                          0.2 mm
                                           ∆x = +4.2mm           1C         0.85      0.06

                     Min Coupling,         ∆x = -3.4 mm         10C         1.47      0.22
                     shifting pencil
                      downward in          ∆x = -3.8. mm         3C         0.95      0.11
                    lateral plane(-X)
                     until charging
                     throttles, then        ∆x = -4 mm          2.5C        1.00      0.09
                    move back by 0.2
                           mm              ∆x = -4.2 mm          1C         0.87      0.06




© 2018 PCTEST LAB                   Page 4 of 8          Test Report S/N: 1C1806050010-12-R2.BCG


                                                                                  FCC Test Results
H-Field and E-Field Measurements
   •   Measurement procedure was performed per FCC KDB Inquiry.
   •   H-Field testing was performed with calibrated field probes (ELT-400).
   •   E-Field testing was performed with calibrated field probe (EHP-200A).
   •   Measurements were performed on the front screen (Top), back shell (Bottom), and side of the
       EUT where the pencil is charging (Side).


                         Probe
                       Distance                                                    Measured Measured
   Measurement                         Pencil                           Charge
                       from the                       Probe plane                   H-Field  E-Field
      Cases                          alignment                          Profile
                          DUT                                                        (A/m)    (V/m)
                         (mm)

                           0              0                  Top                     45.5          5.4
Optimal Placement
                           0              0                 Bottom        10C        29.8          5.0
   (Max Coupling)
                           0              0                  Side                    16.7          2.6



                           0        ∆z = -2.8 mm             Top                     61.6          5.7
   Min coupling,
   shifting pencil
 towards back (-Z)
   until charging          0        ∆z = -2.8 mm            Bottom        10C        39.3          7.8
   throttles, then
  move back in by
       0.2 mm

                           0        ∆z = -2.8 mm             Side                    22.5          3.0




                           0         ∆z = +4 mm              Top                     53.9          6.0
  Min coupling,
  shifting pencil
 towards Display
(+Z) until charging        0         ∆z = +4 mm             Bottom        10C        35.7          5.3
  throttles, then
 move back in by
      0.2 mm
                           0         ∆z = +4 mm              Side                    21.7          4.7




© 2018 PCTEST LAB                             Page 5 of 8            Test Report S/N: 1C1806050010-12-R2.BCG


                                                                  FCC Test Results
   Min coupling,
   shifting pencil
 towards back (-Z)
   until charging    0   ∆z = -3.0 mm           Top         3C         40.7          5.7
   throttles, then
  move back in by
       0.2 mm

   Min coupling,
   shifting pencil
 towards back (-Z)
   until charging    0   ∆z = -3.2 mm           Top        2.5C        48.5          4.9
   throttles, then
  move back in by
       0.2 mm

   Min coupling,
   shifting pencil
 towards back (-Z)
   until charging    0   ∆z = -3.2. mm          Top         1C         38.5          5.0
   throttles, then
  move back in by
       0.2 mm

    Digital Ping           No Pencil      Side (right in
                     0                     front of the    N.A.        69.4          4.6
      (No RX)              (No RX)        TX window)




© 2018 PCTEST LAB                 Page 6 of 8          Test Report S/N: 1C1806050010-12-R2.BCG


                                                                                 FCC Test Results
Conclusion
The worst-case H-Field and E-Field measurements have been determined to be 69.4 A/m and 7.8 V/m
respectively.


Correlation between Measured and Simulated H-Field
Numerical analysis for WPT was carried out to establish correlation between measured and simulated
H-field. Following Table shows that correlation information. The Measured H-field shows good
agreement with Numerical analysis.


                                          H-field Measurements
             BCGA1876                                                   H-field Simulations (A/m)
                                                   (A/m)

                            Probe         Optimal                        Optimal
                          Distance                      Worst Case                    Worst Case
 Charge      Probe                       alignment                      alignment
                          from the                         (Min                          (Min
 Profile    Position                        (Max                          (Max
                            DUT                          Coupling)                     Coupling)
                            (mm)          coupling)                     coupling)

                            0mm             45.5              61.6          47             72

  10C         Top           5mm             26.3              34.3          23             36

                           10mm             14.7              19.6          13             21




Standalone SAR Test Exclusion
Numerical analysis for WPT operation in different orientations for Max and Min coupling configurations
yields SAR values which are < 0.001 mW/g @ Max charge profile of 10C. These values are well below
ambient noise levels measurable in commercially available SAR systems.
There is no intentional transmission taking place in object detection mode. Additionally, the overall duty
cycle of ping mechanism is less than 0.1% hence this mode is not included in analysis.
Based on above, per FCC Guidance, the Apple pencil charging function qualifies for standalone SAR
test exclusion.




© 2018 PCTEST LAB                               Page 7 of 8          Test Report S/N: 1C1806050010-12-R2.BCG


                                                                                     FCC Test Results

Simultaneous SAR Test Exclusion
A comprehensive numerical SAR analysis is carried out for WPT operation in conjunction with SAR
hotspot analysis for WLAN/BT antennas to address compliance in simultaneous transmit conditions.
The Tx coil is very small (~8.3mm) and its at least ~43mm away from the closest radiating element on
its either side.
The SAR gradient for the nearest radiating elements to the WPT Tx Coil is very localized and falls off
substantially at the location of the WPT Tx coil (see Figure 2). SAR hotspot gradient shown in Figure 2
is without the Apple pencil attached to the iPad. With Apple pencil attached to the iPad, SAR will be
lower. Even in the case of dual band operation (5GHz +BT) from a single antenna, the SAR is highly
localized.
Based on above, per FCC Guidance, the Apple pencil charging function qualifies for simultaneous SAR
test exclusion.




                     Figure 2 Right Edge Overlay Showing Localization of Simultaneous Peaks




© 2018 PCTEST LAB                                 Page 8 of 8           Test Report S/N: 1C1806050010-12-R2.BCG



Document Created: 2019-03-24 13:41:20
Document Modified: 2019-03-24 13:41:20

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