802.11 RF Exposure Simulation

FCC ID: NM82Q6U100

RF Exposure Info

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FCCID_4205400

Revision history

Revision Date Description
A March 8, 2019 Initial release
B March 14, 2019 ▪ Modified Section 3.4, Simulation power density results
▪ Modified Chapter 5, Conclusion
▪ Added Table 5-1, Sector mapping from simulation to device
software.

80-YD078-1 Rev. B MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION 2

Contents

1 Scope ..................................................................................................................................... 5

2 Product Description .............................................................................................................. 6
2.1 802.11ad antenna modules ....................................................................................................................... 6
2.2 802.11ad antenna configurations ............................................................................................................... 7

3 Worst-Case Determination Using the Simulation ............................................................... 8
3.1 Modeling .................................................................................................................................................... 8
3.2 Setup ......................................................................................................................................................... 9
3.2.1 Platform .................................................................................................................................... 9
3.2.2 Channels .................................................................................................................................. 9
3.2.3 Error computation and convergence ....................................................................................... 10
3.2.4 Absorbing boundary condition ................................................................................................ 11
3.3 EIRP comparison measured vs. simulation ............................................................................................. 12
3.4 Simulation power density results ............................................................................................................. 12

4 Power Density Measurement ..............................................................................................15

5 Conclusion ...........................................................................................................................16

A Uncertainty Budget .............................................................................................................17
A.1 Simulation uncertainty budget ................................................................................................................. 17

B Simulated Power Density Distributions .............................................................................18
B.1 Left module Cut1 “Front of Device”.......................................................................................................... 18
B.2 Right module Cut1 “Front of Device” ....................................................................................................... 61

C 802.11ad Antenna Modules Images and Drawings .........................................................104
C.1 802.11ad antenna module images inside the EUT ................................................................................ 104
C.2 Simulation modeling drawings ............................................................................................................... 105

80-YD078-1 Rev. B MAY CONTAIN U.S. AND INTERNATIONAL EXPORT CONTROLLED INFORMATION 3

HTC Smart Hub 2Q6U100 802.11ad FCC RF Exposure Simulation Contents

Figures

Figure 3-1 Simulation mesh setup antenna module – Right module ........................................................................... 10
Figure 3-2 Simulation mesh setup used in antenna module – Left module ................................................................. 11
Figure 3-3 Simulated peak power density in 4 cm2-averaged area – Left antenna ..................................................... 13
Figure 3-4 Simulated peak power density in 4 cm2-averaged area – Right antenna ................................................... 14
Figure C-1 802.11ad antenna modules inside HTC 2Q6U100 .................................................................................. 104
Figure C-2 Relative position and orientation of right side and left side antenna modules ......................................... 104
Figure C-3 Orientation of the simulated power distribution relative to the HTC_2Q6U100 device ............................ 105
Figure C-4 Left module ............................................................................................................................................. 106
Figure C-5 Right module ........................................................................................................................................... 107

Tables

Table 3-1 Measured and Simulated EIRP .................................................................................................................... 12
Table 5-1 Sector mapping from simulation to device software ..................................................................................... 16
Table 5-2 Highest simulated power density summary used to define power density measurements ........................... 16
Table A-1 Standard uncertainty budget for simulated values of power density ............................................................ 17

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1 Scope

The purpose of this report is to identify test configurations for measurement of the 60 GHz
802.11ad radios embedded in the HTC Smart Hub model 2Q6U100 for the FCC RF exposure
simulation. This simulation report provides the simulated power density in a 4 cm2 area at a
distance of 10 mm from the device surface.
Two 802.11ad modules were integrated into the 2Q6U100 Smart Hub platform.
■ Each 11ad radio consists of two separate modules (see Section 2.1).
■ Appendix C shows the two 802.11ad antenna module placements.
■ The closest distance between the 802.11ad antenna module and the body or hands of an end
user will be in the near field for the 60 GHz frequency.
Final compliance is evaluated through measurements in a third-party test report.
The RF exposure assessment and simultaneous transmission with other radios supported in the
Smart Hub are evaluated in a separate HTC test report.

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2 Product Description

HTC 2Q6U100 is a Smart Hub integrating the following technologies:
■ FCC LTE bands: B2, B3, B4, B5 , B7, B8, B12, B13, B25, B26, B66, B71
■ TDD LTE bands: B41
■ 5G band: n41
■ 802.11a/b/g/n/ac
■ Bluetooth
■ 802.11ad 60 GHz

2.1 802.11ad antenna modules
The HTC 2Q6U100 Smart Hub integrates two 802.11ad antenna modules operating in the
60 GHz band.
The 11ad antenna modules are connected to a baseboard which receives signals from the
baseband unit.
■ Each 11ad radio consists of two separate modules:
□ 802.11ad antenna module
● 60 GHz RF and antenna array elements on a printed circuit board
● Module interfaces to a baseband unit
□ Baseband unit
● Provides power, control signals, and IF required for the 802.11ad antenna module
■ One 11ad module is located at the right side and the second module is at the left side of the
Smart Hub.
□ The 802.11ad antenna module inside HTC 2Q6U100, and the relative position and
orientation of right and left antenna modules.
● For a closer view of the position and orientation of the 11ad antenna module relative
to HTC 2Q6U100 and the right and left drawings of the 802.11ad antenna module, see
Appendix C.
■ Device firmware selects which 11ad antenna is used for transmission when only one antenna
module can transmit at any one time.
■ These 802.11ad modules (including the antenna modules and baseband unit) support all
mandatory channels in IEEE 802.11ad (i.e., Channels 1, 2, 3 and 4) and comply with the
IEEE 802.11ad standard.

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HTC Smart Hub 2Q6U100 802.11ad FCC RF Exposure Simulation Product Description

2.2 802.11ad antenna configurations
An antenna configuration or sector is a given combination of amplitude and phase of array
elements.
■ There are 32 antenna configurations available for each channel to steer the antenna beam and
establish a good communication link with the best signal to noise ratio.
■ This results in a total 32 antenna configurations available per 11ad array module to handle
surrounding transmission environments.
■ Only one antenna configuration is active at any time.

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3 Worst-Case Determination Using the
Simulation

Depending on the transmission environment, the 802.11ad antenna modules installed inside HTC
2Q6U100 can activate an optimal antenna configuration to establish a good communication link.

NOTE: Simulation modeling drawings are based on the array model provided by Qualcomm
Technologies, Inc. and the 3D platform provided by the EUT manufacturer (see Appendix C.2).

Ansys Electromagnetics suite 18.0.0 simulation software evaluated all possible antenna
configurations to save time.
■ The simulation module includes the 802.11ad antenna module and all components
surrounded within 5λ.
■ The simulation goal is to perform a relative comparison and determine the worst-case antenna
configurations having the highest peak 1 cm2-averaged power density for each channel, and
then perform a power density measurement to demonstrate compliance on the worst cases
identified.
□ It is difficult to accurately simulate power density levels to an absolute-level due to the
lack of accurate material properties for non-metal components at 60 GHz.
□ Final measurement assessment using a larger averaging area will result in lower reported
power density.
□ Based on the placement of the 802.11ad antenna modules, the power density was
simulated on four evaluation planes to determine the worst case antenna configurations:
front, back, bottom, and side (see Figure C-3).
■ The separation distance between the evaluation plane and the corresponding surface of
HTC_2Q6U100 is 10 mm per a KDB discussion with the device manufacture.

3.1 Modeling
Complete models of the top and bottom of the 802.11ad antenna modules are from the antenna
manufacturer, Murata, respectively (see Appendix C.2).
The entire mechanical structure within 4λ surrounding the antenna module are also included in
the simulation.
■ The 3D platform of the device was provided by HTC.
■ With the exception of adhesive materials used in the Smart Hub, all components within a
2 mm radius of 11ad antennas modules are part of the simulation model.
■ All other antennas in the device were also included in the simulation.

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HTC Smart Hub 2Q6U100 802.11ad FCC RF Exposure Simulation Worst-Case Determination Using the Simulation

3.2 Setup
Finite element analysis (FEM) simulations were performed to assess the power density of the
802.11ad antenna module (see Appendix C).
A layered breakdown of the mechanical structure included in the top and bottom modules of the
simulation model:
■ Full model: Entire assembly.
■ Without screen: LCD screen removed (shields, battery, FPCs, screws, LCD mirror and metal
frames) and were modeled as aluminum
■ Only plastic components: All metal parts removed, all non-conductive components were
modeled as lossless ABS material with a relative permittivity of 3.3 and loss tange
The worst-case exposure is expected from the front of HTC 2Q6U100 because exposure from
other directions will be significantly reduced by the surrounding metal components (see top
(Side A) Figure C-1).

3.2.1 Platform
The simulation includes the edge of the platform.
The simulation of the left module was performed with a chuck of the platform that is 34 mm from
the top edge and 43 mm from the left edge.
■ The platform was cut at 20 mm away from the left module’s bottom and right edges to reduce
simulation time.
□ The simulation of the right module was performed with a chuck of the platform that is
32 mm from the top edge and 43 mm from the left edge.
■ The platform was cut at 20 mm away from the left module’s bottom and right edges to reduce
simulation time.
■ The modules are mostly shielded by metallic structures in the –y direction.
□ All components in the vicinity of the module were simulated by assuming they were
mostly made of metal.

3.2.2 Channels
HTC 2Q6U100 supports 801.11ad Channels 1 to 4. Simulations were performed at the center
frequencies of each channel:
■ Channel 1: 58.32 GHz
■ Channel 2: 60.48 GHz
■ Channel 3: 62.64 GHz
■ Channel 4: 64.8 GHz

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HTC Smart Hub 2Q6U100 802.11ad FCC RF Exposure Simulation Worst-Case Determination Using the Simulation

For the complete estimated total simulation uncertainty, see Appendix A.

3.3 EIRP comparison measured vs. simulation
Measured EIRP was compared to simulated EIRP to verify accuracy of the simulation model for
selected test configurations in Table 3-1.
■ As expected, due to unknowns in the device materials, the measured EIRP was less than the
simulated EIRP.
■ The variance was not fully investigated with the expectation that measured power density
results will have greater than 3 dB of margin.

Table 3-1 Measured and Simulated EIRP
Antenna Simulated EIRP Measured EIRP Delta
Channel Sector
Module (dBm) (dBm) (dB)
Left 1 39 19.68 18.21 1.47
Left 2 40 20.66 20.12 0.54
Left 3 38 16.03 17.79 -1.76
Right 1 5 18.9 16.84 2.06
Right 2 5 18.23 19.49 -1.26
Right 3 6 18.24 20.74 -2.5

3.4 Simulation power density results
A total of 1024 antenna configurations (32 configurations per channel) were evaluated at each
evaluation plane for each antenna module.
■ This represents a total of 1024 configurations evaluated to determine the worst-case power
density configurations (32 array configurations x 4 channels x 4 device surfaces x 2 arrays).
■ The surface furthest from the 11ad array on the bottom of the device was not included as it
was >5 cm from the array.
■ The objective of the simulation was to compare the power density levels among antenna
configurations for all evaluation planes to determine the worst-case antenna configuration for
each channel.
■ Then, power density is measured for the identified worst-case antenna configurations to
demonstrate compliance. For measurement setup and test results, see Chapter 4.
■ The term Cut is used to represent a device surface. The mapping of device surface to Cut is
shown in figure Figure C-3.
□ Cut 1= Front surface of the device (closed surface to the array)
□ Cut 2= Rear surface of device
□ Cut 3 = Side surface of the device
□ Cut 4 = Top surface of the device

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4 Power Density Measurement

Power density measurements are not assessed in this test report.

NOTE: See the SPORTON test report for measured test results.

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5 Conclusion

The worst-case antenna configurations having the highest 4 cm2-averaged power density for each
channel and 11ad module, and the 4 cm2 results for comparison in the measurement report are
identified in Table 5-2.
Simulation results are provided for both the top and bottom 11ad antenna arrays on the front, rear,
top, and bottom device surfaces near the antenna array.

Table 5-1 Sector mapping from simulation to device software
Simulation Sector (Used in Right Module Software Sector ID Left Module Software Sector ID
Figure 3-3 and Figure 3-4) (Shown in Table 5-2) (Shown in Table 5-2)
0-31 0-31 32-64

Table 5-2 Highest simulated power density summary used to define power density
measurements
Simulated Pd 4 cm^2 Simulated Pd
Exposure
Module Channel Sector at 10 mm with 4 cm^2 at 10 mm
Plane
100% duty cycle with 85%
Left 1 34 1 8.79 7.47
Left 1 36 1 8.41 7.15
Left 3 34 1 8.71 7.40
Left 3 40 1 8.70 7.40
Left 4 37 1 8.50 7.23
Left 4 36 1 8.33 7.08
Left 1 33 2 0.49 0.41
Left 1 58 3 5.19 4.41
Left 4 50 4 4.86 4.13
Right 1 10 1 8.60 7.31
Right 1 20 1 8.20 6.97
Right 2 3 1 8.10 6.89
Right 2 12 1 7.59 6.45
Right 4 12 1 8.10 6.89
Right 4 3 1 7.84 6.67
Right 2 13 2 0.76 0.65
Right 2 18 3 3.52 2.99
Right 4 8 4 2.64 2.24

For complete simulation results of point power density distributions on the back plane (bottom
module) and front plane (upper module) for all antenna configurations, see Appendix B.

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A Uncertainty Budget

A.1 Simulation uncertainty budget
Table A-1 lists the measurement uncertainty analysis for the simulation.

Table A-1 Standard uncertainty budget for simulated values of power density
Uncertainty Std. unc Std. unc
# Description Prob. dist. Div.
(± %) (± %) (± dB)
1 FEM mesh density 0.10% Norm 1 0.10% 0.00
2 Boundary condition 0.80% Norm 1 0.80% 0.03
3 Convergence 0.50% Norm 1 0.50% 0.02
Combined standard uncertainty 0.9% 0.04

Expanded standard uncertainty 1.9% 0.08
1 Mesh density on the exposure plane was changed by limiting the "max length" of mesh size
from auto setting (9.6 mm) to 2 mm.
2 Simulation domain (volume) was decreased by 30% to check the influence of reflections from

boundary conditions on power density.
3
5% versus 3% convergence criteria were compared in Ansys Electromagnetics Suite 18.0.0.

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Document Created: 2019-03-14 22:55:17
Document Modified: 2019-03-14 22:55:17

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