Upload
deepti-chahar
View
217
Download
0
Embed Size (px)
Citation preview
8/17/2019 Bio Effects of Mobile Phones
1/40
1
Introduction on MobilePhone SimulationsBiological Models
SAR SimulationsHearing Aid Compatibility
www.cst.com
Tilmann Wittig
Bio-Effects of Mobile PhonesUGM 2009 Darmstadt
8/17/2019 Bio Effects of Mobile Phones
2/40
2 www.cst.com
Simulation at various levels ofcomplexity
SonyEricsson M600
Antenna level Phone level Body effects, head (SAM) and hand
8/17/2019 Bio Effects of Mobile Phones
3/40
3 www.cst.com
Antenna level simulationReturn loss (S11)
(farfield pattern)Radiation efficiency
accurate modelling of losses important
Simulation accuracy -40dB (careful with AR-filter)
Simulation time: 11 Minutes
8/17/2019 Bio Effects of Mobile Phones
4/40
4 www.cst.com
Antenna level simulation
900 MHz 1800 MHz
8/17/2019 Bio Effects of Mobile Phones
5/40
5 www.cst.com
Full phone level simulation
STEP Import of complete phone
8/17/2019 Bio Effects of Mobile Phones
6/40
6 www.cst.com
Full phone level simulation
Simulation time: 19 Minutes
As well: Return loss (S11) and radiation efficiencyHearing Aid Compatibility (HAC)Total Radiated Power (TRP)Total Isotropic Sensitivity (TIS)
Agreement still good, but some uncertainties for materials, simplifications, …
8/17/2019 Bio Effects of Mobile Phones
7/407 www.cst.com
Full phone level simulation, HACHAC: nearfield interacting with other devices,
such as hearing aids
8/17/2019 Bio Effects of Mobile Phones
8/408 www.cst.com
Full phone level sim., Matching
Phone + PCB + antenna matching network simulated in CST DESIGN
STUDIO to calculate total radiated power (TRP)
8/17/2019 Bio Effects of Mobile Phones
9/409 www.cst.com
Phone + human simulation
900 MHz 1800 MHz
erad phone Phone head Phone headhand
897,4 MHz 100 % 23 % (-6,3 dB) 6 % (-12.2 dB)
1747,6 MHz 100 % 48 % (-3.2 dB) 7 % (-11.5 dB)
Radiation efficiency
SAR
8/17/2019 Bio Effects of Mobile Phones
10/4010 www.cst.com
Phone + human simulation
Farfield for antena in thepresence of human model
900 MHz 1800 MHz
8/17/2019 Bio Effects of Mobile Phones
11/4011 www.cst.com
Specific Absorbtion Rate (SAR)
900 MHz 1800 MHz
8/17/2019 Bio Effects of Mobile Phones
12/40
12 www.cst.com
Biological ModelsThe right choice of the biological model is essential for the reliabilityof a SAR or EMI simulation.
Visible Humanvoxel data
SAM Phantom
other voxel data
8/17/2019 Bio Effects of Mobile Phones
13/40
13 www.cst.com
SAM - Standard Anthropomorphic Model
www.sam-phantom.com
Frequency dependent materialproperties (according to
standard) can be modelled bydispersive materials via
tabulated input.
Only one simulation run forbroadband results!!
tissuesimulant
liquid(TSL)
plastic shellOriginally created for measurementsShape specified in IEEE/CENELEC/IEC standardsFilled with homogeneous glycol-containing tissue-simulant liquid, only two materials for simulation
Virtual prototyping through simulation
8/17/2019 Bio Effects of Mobile Phones
14/40
14 www.cst.com
Homogeneous Hand/Body Models
Posable homogeneous hand/body models are available for CSTFor most high frequency applications fully sufficientSimulate much faster then voxel models
8/17/2019 Bio Effects of Mobile Phones
15/40
15 www.cst.com
Homogeneous Full Body Models
8/17/2019 Bio Effects of Mobile Phones
16/40
16 www.cst.com
Visible Human (HUGO)
Available indifferent
resolutions
Materials ofinterest can be
chosen
Much more accurate and detailled modelling of the biological tissue
Visible Human Projectproduced by the National Library ofMedicine (NLM), Marylandhttp://www.vr-laboratory.com/
8/17/2019 Bio Effects of Mobile Phones
17/40
17 www.cst.com
General Voxel ModelsAny voxel model can be imported in CST MICROWAVE STUDIO®
8/17/2019 Bio Effects of Mobile Phones
18/40
18 www.cst.com
Dispersive Broadband Simulation
Re( r) Im( r)
0.9 GHz 41.5 17.98 (= 0.9 S/m)
1.8 GHz 40.0 13.98 (= 1.4 S/m)
Typical requirement for dual band phones:
Frequency dependentmaterial definition:
Second order dispersivefit for tabulated values,only one simulation run
required
8/17/2019 Bio Effects of Mobile Phones
19/40
19 www.cst.com
Dispersive Broadband SimulationCompared material settings:
Constant settings for 0.9 GHzsim. time 45 min.
Constant settings for 1.8 GHzsim. time 45 min.
Dispersive broadband fittotal sim. time: 57 min.
Dispersive fit agrees very well for S-Parameter and SARvalues in both bands for only 25% extra simulation time
0.9 GHz, 1g 1.35 1.31 1.74
0.9 GHz, 10g 0.96 0.93 1.13
1.8 GHz, 1g 0.69 1.32 1.32
1.8 GHz, 10g 0.99 0.83 0.83
S-Parameter comparison:
SAR value comparison:
8/17/2019 Bio Effects of Mobile Phones
20/40
20 www.cst.com
Cole-Cole-Materials
8/17/2019 Bio Effects of Mobile Phones
21/40
21 www.cst.com
SAR
8/17/2019 Bio Effects of Mobile Phones
22/40
22 www.cst.com
Overview and Background
SAR – Specific Absorbtion Rate
Unit of SAR: W/kg
P : Power loss densityE : Electric field strength
J : Current densitys: Conductivityr : DensityTypically averaged over pre-defined mass
A measure for electromagnetic energy absorbed by biologicaltissue mass when exposed to radiating device (e.g. mobile phone)
22
22 J E P SAR
8/17/2019 Bio Effects of Mobile Phones
23/40
23 www.cst.com
Definitions
Point SAR : Local SAR without mass or volume averagingTotal SAR : Total power loss in the whole lossy structure divided byits total mass
Mass Averaged SAR (typically 1g or 10g):
For each point a cube with a defined mass is foundThe power loss density is integrated over this cubeThe integral power loss is divided by the cube‘s mass
Volume Averaged SAR: Procedure as above, but on fixed volume.
Typical Standards, maximum of mass averaged SAR:US and Canada: 1.6 W/kg averaged over 10g of tissueEU, Japan, Brazil: 2.0 W/kg averaged over 1g of tissue
8/17/2019 Bio Effects of Mobile Phones
24/40
24 www.cst.com
Averaging Procedure
1. Point of avg. SAR calculation2. Search for 10 g cube (iteratively)3. Integrate losses in cube
At boundary treatment dependson chosen averaging standard:IEEE C95.3 / CST C95.3CST legacy
The „constant volume“ assumption uses an averaged cube size:- Faster (no iterative search for cube with correct mass)
- Only approximative (not according to official SAR standard)
8/17/2019 Bio Effects of Mobile Phones
25/40
25 www.cst.com
SAR Standards under Development
Several guidelines and standards specify SAR safety limits (i.e. ICNIRP).
Standards like IEEE 1528 regulate measurement methods for practicalassessment of compliance.
A simulation standard IEEE 1528.X is in development1528.1 requirements for hexahedral time domain codes (end of 2008)1528.2 application to cars with passenger/bystander (~2009)1528.3 application to mobile phones near head (~2009)1528.4 requirements for tetrahedral frequency domain codesCST participates in standards committee .
IEEE C95.3 Annex E specifies SAR averaging scheme for simulation.CST MICROWAVE STUDIO® has already been approved by the FCC (USA)to comply with hex td standard drafts.
8/17/2019 Bio Effects of Mobile Phones
26/40
26 www.cst.com
SAR Handling inCST MICROWAVE STUDIO®
Pre-conditions before start of simulation:A power-loss monitor needs to be defined at frequencies of interest .All materials used for mass averaging need to have mass density ρ .
Choose the Powerloss monitor
Definition of averaging massor Point SAR
Define labeling
8/17/2019 Bio Effects of Mobile Phones
27/40
27 www.cst.com
SAR Special Settings
Define reference power,Port input or accepted power
Restrict volume for:- maximum search and statistics
- reduced computational effort
Choose averaging method
8/17/2019 Bio Effects of Mobile Phones
28/40
28 www.cst.com
Template Based Postprocessing
Alternatively: Postprocessing Templates can be defined
Available as 1D and 0Dresult template
8/17/2019 Bio Effects of Mobile Phones
29/40
29 www.cst.com
SAR Results
Generalinformation
Statistics fortotal volume(e.g.head + hand)
Statistics forSubvolume(e.g. just head)
8/17/2019 Bio Effects of Mobile Phones
30/40
30 www.cst.com
Visualization of SAR 2D or 3D plot including information about position of the maximum
8/17/2019 Bio Effects of Mobile Phones
31/40
31 www.cst.com
Visualization of Max. SAR Cube
8/17/2019 Bio Effects of Mobile Phones
32/40
32 www.cst.com
PBA®, TST™ and Subgridding
1mm voxel
resolutionnear ear
0.3mm gridat helix
with PBA®
30mm grid
at openboundary
8/17/2019 Bio Effects of Mobile Phones
33/40
33 www.cst.com
Visible Human SAR
SAR 10g [W/kg]SAR 1g [W/kg]
Subgridding allows high resolution SARevaluation in critical regions
8/17/2019 Bio Effects of Mobile Phones
34/40
34 www.cst.com
Performance Summary
SAMNo Subgrid
SAMSubgrid
VoxelNo Subgrid
VoxelSubgrid
Mesh cells 2.1 M 163k 2.9 M 288k
Solver time 5,486 s 568 s 7,281 s 1,867 sSAR time 1g 209 s 39 s 781 s 140 s
SAR time 10g 1,080 s 51 s 4,292 s 185 s
Acceleration Factor 10 Factor 5.6
Software performance on Intel Xeon 3 GHz, 2 GB RAM(Hardware acceleration will increase performance by additional factor)
8/17/2019 Bio Effects of Mobile Phones
35/40
35
Bioheat Simulation
See last presentation in this session
8/17/2019 Bio Effects of Mobile Phones
36/40
36 www.cst.com
Hearing Aid Compatibility (HAC)Requirements for HAC evaluation:
Define E- AND H-fieldmonitors for all frequenciesof interest
Define and store a WorkingCoordinate System (WCS) at thespeaker point, aligned with thephone
8/17/2019 Bio Effects of Mobile Phones
37/40
37 www.cst.com
Hearing Aid Compatibility (HAC)Pick HAC as 0D result template:
Specify speaker point WCS
Choose ArticulationWeighting Factor(AWF) according totransmission protocol
Choose evaluation resolution
Choose frequency and port
Specify accepted orStimulated power
8/17/2019 Bio Effects of Mobile Phones
38/40
38 www.cst.com
Hearing Aid Compatibility (HAC)After Evaluation check log-file:
Logfile contains initial field values,scaled field values, field exclusionscheme and final HAC categoryaccording ANSI C63.19
8/17/2019 Bio Effects of Mobile Phones
39/40
39 www.cst.com
Hearing Aid Compatibility (HAC)Field plots andHAC segments:
8/17/2019 Bio Effects of Mobile Phones
40/40
Summary
All advantages of CST MWS (PBA®, TST™, MSS™, ...)apply to SAR simulations
Frequency dependent materials: Broadband SAR in onesimulation run
One tool for both antenna design and SAR verification
Support of various standards, participation in IEEEstandard committees
Simplified and more flexible handling of voxel models
SAR simulations with CST MICROWAVE STUDIO®