2008 international ansys conference · 2008 international ansys conference integrating automotive...

© 2008 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

2008 International ANSYS Conference

Integrating Automotive Electronics Before Fabrication

Matthew H. Commens, Ph.D. Technical Director, HF Products Ansoft LLC


• Recent technology implementations have increased the requirement for antenna analysis in automotive design.– Digital FM radio– Remote keyless entry (RKE)– Tire pressure monitoring systems (TPMS)– Global position systems (GPS)– Satellite radio service (SDARS)– Bluetooth and WiFi– Proximity and collision avoidance radar

Automotive Antenna Systems


Automotive “Antenna” Systems, cont.

• Experts predict by 2010, 30% of an automobile’s cost will be in electronic components.– Electromagnetic Compatibility (EMC)

will become a more critical aspect of the automotive design.

– Very important issue for alternative powertrains due to higher system voltages.

• These components may unintentionally radiated causing EMI/EMC problems.

• Predicting antenna and EMC performance via electromagnetic simulation will allow for further cuts in design cost and cycle times.


• Understand the radiation characteristics, emission and susceptibility for devices in cars.– Vehicles are large and complex– Resort to simplified models of cars

• Recent advances in simulation technology and hardware allow for simulation of realistic vehicle models.

Electromagnetic Vehicle Simulation


Ansoft’s HFSS Overview

• HFSS = High Frequency Structure Simulator: – The keystone to radiation and

EMI/EMC analysis• 3D electromagnetic extraction using

tetrahedral finite elements– conformal = precise– non-uniform = efficient– auto-adapted = accurate

• Full wave solution– S-parameters, surface currents

and radiated field outputs


Ansoft’s HFSSTM

• 3D Full-wave Electromagnetic Field Simulation– Ansoft’s HFSS™ is the industry-standard for 3D

electromagnetic field simulation and S-parameter extraction of high-frequency/high-speed components and systems.

– Engineers rely on the accuracy, capacity, and performance of HFSS to design…• On-chip Embedded Passives, IC packages, PCB interconnects,

Antennas, RF/microwave components, Biomedical Devices…..

– HFSS improves engineering productivity, reduces development time, and better assures first-pass design success.


• Uses the Finite Element Method to solve Maxwell‘s Equations– 3D discretization through tetrahedra

• Tetrahedral mesh conforms to arbitrary geometry

– Uses transfinite element method to solve directly for s-parameters.

– Automatic adaptive mesh generation increases mesh density in regions where higher accuracy is needed

• Allows engineers to visualize 3D electromagnetic fields, generate s-parameters and extract full-wave SPICE compatible models

Ansoft’s HFSS Technology


Overview of HFSS Capabilities

• HFSS Desktop– ACIS-based parametric modeling with

dynamic editing for design flow automation– Report generation and field visualization

• Material types and boundary conditions– Frequency-dependent materials– Non-linear and anisotropic materials– Absorbing BCs for open problems– Symmetry, finite conductivity, and RLC– Master/slave for unit cell models

• Solver technology– Automatic, adaptive conformal mesh– External/internal excitations with loss– Adaptive Lanczos-Pade sweep – Eigenmode solver


S-parameters and SPICE models from HFSS

• Modal/Terminal/Differential– S, Y, Z-parameters, complex

propagation constant Г and Z0

• Common Output Formats– S-parameters

• Touchstone, Matlab, Citifile, NMF– Full-Wave Spice

• Broadband and lumped RLC, Partial fraction (Matlab), HSPICE, PSPICE and Cadence Spectre

• Common Display Formats– Rectangular and polar plots, Smith

charts and data tables


Fields from HFSS

• Field Outputs– Electric and magnetic fields– Volume and surface current– Power and specific absorption rate (SAR)– User defined via “fields calculator”

• Radiation– 2D/3D near-fields and far-fields– Periodic and custom arrays– Radar cross section (RCS)

• Common Display Formats– Vector/scalar plots - volumes/surfaces– 2D reports (rectangular, polar, patterns,

data tables)– Animations (AVI and GIF)

0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00rotAngle [deg]

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Com

plex

Mag

_E

Ansoft Corporation CadiSimpleXY Plot 1Curve Info

ComplexMag_E434MHz : LastAdaptiveFreq='0.434GHz' Phase='0deg'


Ansoft HFSS User Interface

Progress Window

Property Window

Message Manager

ProjectManager

3D Modeler

Model Tree


• 11.5 GHz patch antenna

• Mesh elements concentrate about the perimeter of patch.

• Accurate mesh representation automatically generated by HFSS

Ansoft’s Adaptive Meshing: A Key Technology


Efficiency Improvement: 64-bit Computing

• 64 bit computing available for a number of years.– Supercomputers since the 1960s– RISC based architecture since the 1990s– Personal computers in 2003

• Provides access to a large amount of memory– Theoretically 16 exabytes (17.2B GB)

• Cost of hardware (memory) no longer prohibitive


Efficiency Improvement: Hierarchical Elements and Iterative Solver

• Hierarchical vector basis– 0th, 1st and 2nd orders– Appropriate order applied

for given geometry• Iterative solver requires less

memory than direct– Uses direct solve from

next lowest order as pre-conditioner

v0

v1

v3v

2v0

v1

v3v

2

v0

v1

v3v

2

v0

v3v

2

v1

v0

v3v

2

v1

v0

v1

v3v

2


Efficiency Improvement: Distributed Analysis

• Distributed Analysis = DSO (Distributed Solve Option)– Distributes parametric studies across available hardware to

expedite electromagnetic extraction, characterization and optimization.

……

Host Computer

Remote Computers

1 2 3 4 n


DSO: Parametric Sweep…

• Process• Host computer creates the

mesh• Each sweep iteration is sent

to a separate computer• As each computer finishes an

iteration, a remaining iteration is sent to that computer

• DSO may also be applied to frequency sweeps


Example 1: FM Radio Antenna

• Chrysler PT cruiser with FM “whip” antenna


Example 1: FM Radio Antenna

• Directivity at horizon• 3D far field pattern• Surface currents

– Different grounding


Example 2: Remote Keyless Entry (RKE)

• Receiver antenna packaging : Utilize idealized Hertzian dipolesource– Infinitesimally small

dipole source– Closed form solution

for excitation– Computationally

inexpensive


Example 3: Tire Pressure Monitoring System(TPMS)


Example 3: TPMS - Mesh Generation

• Geometrically conformal mesh automatically created and adapted for each iteration– Engineer not required to create each mesh– E-field at IP

0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00rotAngle [deg]

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Com

plex

Mag

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Ansoft Corporation CadiSimpleXY Plot 1Curve Info

ComplexMag_E434MHz : LastAdaptiveFreq='0.434GHz' Phase='0deg'


Example 4: Roof Mounted GPS

• GPS antenna mounted on roof– Circular patch

• Volume = 2500 λ3

• “Sea urchin” pattern from image ground currents on body


0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60Freq [GHz]

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s10

Adapt_Pass_Compare

EMI/EMC: Shielding Enclosure Standard

• EMC standard from ACES (Applied Computational Electromagnetic Society)– Shielded

enclosure– Good test for

accuracy


Example 5: Wire Harness

• Chrysler PT Cruiser with common mode signal on wire harness. @ 50 MHz,

• “Bundle of wires” simulated as one “wire” with single ended common mode excitation ports.


Example 6: Mobile Phone in Auto

• What if radiator not connected to enclosure– E.g. mobile phone in

auto• Solve mobile device

alone and impress fields from this solution into simulation car. @ 900 MHz, 1.1 GB– HFSS to HFSS link.


• Monitor radiation from DVD player• Utilize Ansoft’s SIwave to model PCB of

DVD.• SIwave – HFSS link

Example 7: DVD Player in Headrest


• Complex PCB electromagnetic analysis tool.• How does it work?

– Judicious application of full-wave solvers breaks a complex problem into a collection of simpler problems.

– Radiated fields included.• Radiated fields from PCB can be impressed into an HFSS

simulation. The SIwave - HFSS link

Example 7: SIwave


Example 7: More on SIwave

VV

High |Z| at 137 MHzLow |Z| at 50 MHz


Fields from DVD Player

Source Locations


SIwave linked data:Radiated source fields from DVD. @ 125 MH

Example 7: More on SIwave


Conclusions

• Increasing electronic content in automotive design motivating component and system simulation to determine radiation (good and bad) characteristic

• Improved software algorithms and techniques along with increased hardware capability allow for simulation of detailed systems

• This Simulation Driven Product Development will allow for reduced design and hardware cost along with reduction in design time for fastest to market results

2008 international ansys conference · 2008 international ansys conference integrating automotive...

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