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15. 0 Release
ANSYS Inc
HFSS for Electrically Large Antenna System Design: Hybrid Simulation Technology
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 2 November 14, 2012
Agenda
• HFSS 3D Platform Simulations • ANSYS Simulation Technologies Overview
– ANSYS Electromagnetic Simulation Techniques • HFSS-FEM (Finite Element Method) • HFSS-IE (Integral Equation) • HFSS-PO (Physical Optics) • Hybrid FEM-IE • Enhanced Hybrid IE-Regions
– MPI (Message Passing Interface) Based DDM (Domain Decomposition Method) • HFSS • HFSS-IE • Hybrid FEM-IE
• Examples
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 3 November 14, 2012
• Full 3D System Simulations – Simulate more complicated and electrically large problems – Require efficient simulations
HFSS 3D System Simulations
Courtesy of Raytheon
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 4 November 14, 2012
Technology Review
• 3D Simulation Technology – HFSS: 3D Finite Element Method – HFSS-IE: 3D Method of Moments – HFSS-IE: 3D Physical Optics (PO) – HFSS+HFSS-IE: 3D Hybrid Simulations
HFSS: Cell Phone Tower
HFSS: Antenna Array
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 5 November 14, 2012
HFSS-IE: 3D Method of Moments
• 3D Integral Equation technique – Automated results with accuracy
• Automated adaptive meshing technique – Ensures accuracy
• Employs Adaptive Cross Approximation (ACA) technique for larger simulation – RAM and runtime scale as N*log(N)
– Easy to use interface • Implemented as a new design type in the HFSS desktop
– Utilization of results from HFSS as a linked source • Link can include effects of backwards scattering to the source geometry
• Target applications: – Large, open, radiating or scattering analyses
• Antenna placement, co-site • Radar cross section (RCS)
Pass #
Del
ta S
HFSS-IE: 3D MoM with Adaptive Meshing
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 6 November 14, 2012
Example: HFSS-IE (3D MoM)
HFSS HFSS-IE
Time 6 hours 1:15 hour
RAM 98 GB 41 GB
13072 λ³
Roof Monopole
HFSS-IE: 4.8x faster and 58% less RAM
HFSS-FEM
HFSS-IE
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 7 November 14, 2012
HFSS-IE: Physical Optics (PO)
• Asymptotic solver for large metallic models – Solves electrically huge problems – Currents are approximated in illuminated regions
• Set to zero in shadow regions – No ray tracing or multiple “bounces” – Sourced by incident wave excitations
• Plane waves or linked HFSS designs as a source
• Target applications: – HFSS to HFSS-PO Datalink
• Large reflector antennas • Antenna placement on large platform
– RCS of large objects such as satellites
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 8 November 14, 2012
Diameter = 0.667 λ Diameter = 33.33 λ Diameter = 6.667 λ
The higher the frequency is, the ‘more’ accurate the PO will be
IE PO IE PO IE PO
Red – PO Blue - IE
Example HFSS-IE: 3D MoM vs. Physical Optics
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 9 November 14, 2012
Hybrid FEM-IE Method • Radiation: Finite Element-Boundary Integral
• IE-Regions: Finite Elements + 3D MoM
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 10 November 14, 2012
HFSS Hybrid Technology • HFSS Hybrid Technology*
– Hybrid Radiation Boundary • Finite Element Boundary Integral (FE-BI) • Truncate an FEM Volume with any arbitrary surface using integral equations
– Hybrid IE-Regions • Two-way coupling between Finite Element Volumes with FE-BI radiation boundaries to a 3D
Method of Moments region. • Free Space Coupled
– Conducting objects outside of FEM solution space can be solved directly with 3D MoM, eliminating the need for conducting objects to be enclosed in an air volume
– Homogenous dielectric volumes can be removed from the FEM solution and replaced with the equivalent 3D MoM solution in the region, useful when dielectric regions are electrically large requiring large FEM solution volume
• Free Space + Current CoupledNew
– In addition to Free Space coupling, IE-Regions can touch the FE-BI boundary. – Metallic structures can connect across domains allowing electric current to flow from metallic
objects in the FEM Volume to touching metallic objects in 3D MoM region
*Requires HFSS-IE solver license
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 11 November 14, 2012
Hybrid Radiation Boundary
• Radiation Technologies: – Absorbing Boundary Condition (ABC) – First Order Approximation to Free Space – Perfectly Matched Layer (PML) – Anisotropic Absorber – Finite Element – Boundary Integral (FE-BI) – Hybrid FEM+IE for Radiation
• FE-BI Advantages – Arbitrary shaped boundary
• Conformal and discontinuous • Minimize FEM solution volume
– Reflection less boundary condition • High accuracy for radiating and scattering problems
– No theoretical minimum distance from radiator • Reduce simulation volume and simplify problem setup
– Boundary Coupling • Disjoint FEM volumes couple via FE-BI boundaries
– Setup is similar to ABC boundary condition • Enabled by checking “Model exterior as HFSS-IE domain”
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 12 November 14, 2012
HFSS Example: FE-BI
HFSS with PML
• FE-BI significantly reduces required computer resources
– Large air volume inside of radome is removed from the FEM solution
• Air volume is required if using PML or ABC – Two FEM-IE domains are applied
• Conformal to radome • Conformal to horn antenna (26 GHz)
26 GHz RAM Elapsed Time
PML 259G (DDM) 840min
FE-BI 64G 205min
19143 λ³
FE-BI shows 4.1x speedup factor and 75% less RAM
HFSS with FE-BI
FEM-IE Surface
2860 λ³
Radome Horn Antenna
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 13 November 14, 2012
• HFSS with IE-Regions: Free Space Coupled – Metal objects can be solved directly with an IE solution applied to surface
• Removes the need for air box to surround metal objects – Homogeneous dielectric objects can be replaced with IE-Region
• Dielectric is solved using IE to surface
IE-Regions (6.2G RAM)
Hybrid IE-Regions: Free Space Coupled
❶Dielectric IE-Region
Metal
Dielectric εr = 4
FEM Solution (20G RAM)
IE-Regions reduces RAM by ~70%
❷Metallic IE-Region
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 14 November 14, 2012
HFSS Hybrid IE-Regions with Current Coupling
• HFSS Hybrid IE-Regions – In HFSS 15, metallic objects from IE-Regions are allowed to touch FE-BI boundaries.
This new capability allows electric current two-way coupling between the Finite Element domain and the 3D Method of Moments domain.
– Usage • Finite Element Domains are used to solve complex materials and excitations • 3D Method of Moments (IE-Regions) are applied on electrically-large platform(s)
❶FEM-IE domains: Complex antenna as patch array
Non-metallic parts as canopy
❷IE-Region:
metallic body, missiles etc
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 15 November 14, 2012
HFSS Hybrid IE-Regions with Current Coupling
FEM FEM-IE touching IE-Region Time 9.1 hours 4.5 hours RAM 98 GB 23.7G
❷IE-Region
❶FE-BI
❶ FE-BI
❶ FE-BI
HFSS FEM PML
10625 λ³
HFSS Hybrid 37 λ³
18.4 meter
Hybrid solver is 2x faster, and uses 76% Less RAM
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 16 November 14, 2012
HFSS Hybrid IE-Regions with Current Coupling
81% Less RAM: IE-Region vs. FEM
140G RAM
44G RAM
Black - FEM Red – Hybrid IE-Regions
FEM with ABC 231G RAM
22463 λ³
199 λ³
Hybrid IE-Region 44G RAM
❶FE-BI
❷IE-Region
50 λ
Continuous Current across FEM and IE-Region
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 17 November 14, 2012
High Performance Computing Increase simulation capacity using High Performance Computing (HPC)
New MPI Based Domain DDM • HFSS-FEM • HFSS-IE • HFSS Hybrid FEM-IE and enhanced IE-Regions
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 18 November 14, 2012
Leveraging High Performance Computing Hardware
Multi-Threading
Spectral Domain Method Distributed Frequency Sweeps
Distributed Parallel Solvers HFSS-Transient
HFSS DDM Mesh based Domain Solver
HFSS Periodic Domains Finite Array Domain Solver
HFSS-IE DDM Matrix based Domain Solver
HFSS-Hybrid DDM Hybrid HFSS/HFSS-IE Domain Solver
Faster
Bigger
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 19 November 14, 2012
HPC for HFSS 15.0
• HPC Improvements for HFSS 15.0 – New multi-threaded matrix solver
• Up to 5x faster solver – 20% faster then previous generation multi-processing license
– Improved Distributed Frequency Solver
– MPI based Domain Solvers • Industry Standard MPI • Faster communication between domains
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 20 November 14, 2012
• Multi-Threading (HPC-MT) – Single workstation solution to increase the speed of the solver – TAU Initial Mesh Generation
• Parallelized mesh generation – Direct Matrix Solver
• Parallelized matrix solver – Iterative Solver
• Parallelized matrix pre-conditioner • Parallelized excitations
– Field Recovery • Parallelized field recovery for multiple excitations
– Available with HFSS, HFSS-IE, and HFSS-Transient
HPC: Multi-Threading (MT)
HFSS – HPC-MT Processor Performance* Up to 5x faster solver.
4 Cores
8 Cores
2 Cores
1 Core 1x
1.9x
3.6x
5.6x
(Baseline) No HPC
Thread 1 Thread 2
Thread 3 Thread 4
*HFSS Direct Matrix Solver
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 21 November 14, 2012
• Spectral Decomposition Method (HPC-SDM) – Accelerates frequency sweeps by distributing the
spectral content across a network of processors – Increases simulation speed
• Combines with HPC-MT – Scalable to large numbers of cores – Available with HFSS, HFSS-IE, and PSI
HPC: Spectral Domain Method
Frequency 1
Frequency 4
Frequency 3
Frequency 2
*Interpolating Sweep: 0-20GHz, 201 frequencies
HFSS Frequency Sweep – HPC-SDM* Ultrafast frequency sweeps 32 SDM Points
8 SDM Points
Serial Sweep 1x
5.3x
16.6x
(Baseline) No HPC
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 22 November 14, 2012
HPC: HFSS-DDM (Mesh Based)
• Domain Decomposition Method: Meshed Based – Distributed memory parallel technique
• Distributes mesh sub-domains to network of processors/RAM – Significantly increases simulation capacity – Highly scalable to large numbers of processors
• Uses industry standard MPI • Combines with HPC-MT
– Automatic generation of domains by mesh partitioning • User friendly • Load balance
– Hybrid iterative & direct solver • Multi-frontal direct solver for each sub-domain • Sub-domains exchange information iteratively
via Robin’s transmission conditions (RTC) – Available with HFSS
Domain 1
Domain 4
Domain 3
Domain 2
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 23 November 14, 2012
HPC: HFSS-DDM (Mesh Based)
2meter aperture diameter @7.6GHz (50 λ aperture)
HFSS v14 HFSS v15 Improvement
Elapsed Time 5.5 hours 4.5 hours 1.2x
Red – v15 Blue – v14
HFSS v15 is 1.2x faster with new MPI DDM Solver and new Multi-threading solver
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 24 November 14, 2012
Incident Wave
• Domain Decomposition Method: Matrix Based – Distributed memory parallel technique
• Distributes matrix solution to network of processors/RAM – Significantly increases simulation capacity – Highly scalable to large numbers of machines
• Uses industry standard MPI • Combines with HPC-MT
– Automatic generation and load balancing of matrix partitions – Available with HFSS-IE
HPC: HFSS-IE DDM (Matrix Based)
Domain1
Domain 3
Domain 2
Domain 4
18 GHz RAM Elapsed Time
HFSS-IE HPC-DDM
146G 7.3h
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 25 November 14, 2012
MPI Based DDM for HFSS-IE Example
1.7x Speedup with 2 HPC Pack (14% more RAM) 2.4x Speedup with 3 HPC Pack (57% more RAM)
8
1HPC 2HPC 3HPC
8
17.4x13.7x3.1 meters 2.45GHz
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 26 November 14, 2012
❷IE-Region
❶FEM-IE
❶ FEM-IE
❶ FEM-IE
• Domain Decomposition Method – Distributes mesh sub-domains to network of processors
• FEM volume can be sub-divided into multiple domains • IE Domains that are discontinuous will be distributed to separate nodes when they become large
– Significantly increases simulation capacity – Uses Industry Standard MPI – Extension of HFSS DDM to support the Hybrid FEM/IE solver
• IE Regions & FE-BI – Available with HFSS+HFSS-IE Hybrid
HPC: Hybrid HFSS - FEM DDM with IE Regions
Domain 1
IE-Domain
Domain 3
Domain 2
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 27 November 14, 2012
Hybrid HFSS - FEM DDM with IE Regions
36.2 λ
37 λ
58 λ
46 λ
>900,000 λ³
95 λ
Courtesy of Raytheon
Beam Waveguide
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 28 November 14, 2012
Beam Waveguide Full-Wave Solution
FE-BI
Courtesy of Raytheon
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 29 November 14, 2012
Beam Waveguide Model
Local vs. MPI
Local Machine MPI with 5 domains
HPC speed up of 2.1x
16 cores 6 cores 6 cores 6 cores 6 cores 6 cores
RAM Time
Local 80G 5h35m
HPC-DDM 56G 2h39m
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 30 November 14, 2012
Examples
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 31 November 14, 2012
F16 Antenna Placement @ 1060 MHZ
4 Antennas
2 Antennas
2 Antennas
1 Antenna
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 32 November 14, 2012
Only 32% longer and 26% more RAM: 4 excitations vs. 1 excitation
F16 Antenna Placement @ 1060 MHZ Adaptive Mesh
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 33 November 14, 2012
Reflector Antenna (FEBI/IE-Region/PO Datalink)
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 34 November 14, 2012
Cassegrain Reflector Antenna Example
0.32-meter Sub-parabolic (9.6 λ) 2-meter main parabolic (60λ) Frequency = 9GHz
37G RAM, 3.2 hours
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 35 November 14, 2012
Large Reflector Antenna Simulation Full-wave Solution
2.7 million unknowns 373G RAM 71.4 hours
150 λ
45 λ
❶ FEM-IE
❷ IE-Region
Horn
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 36 November 14, 2012
Large Reflector Antenna Simulations HFSS to PO Datalink
FEM to HFSS-PO Datalink
❶ HFSS for Fed Horn
❷ HFSS-IE Design for Parabolic
1.7G RAM 3 minutes
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 37 November 14, 2012
Full-wave vs. HFSS to PO Link
Red- HFSS to PO Link Blue – Hybrid FEM-IE
Less than 0.5 dB peak-gain difference (48dB) using HFSS to PO Link
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 38 November 14, 2012
RCS from Electrically-Large Models (HFSS-IE/PO)
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 39 November 14, 2012
Harm RCS @ 18GHz
Red – IE Blue - PO
HFSS-IE HFSS-PO
RAM 146G 2.24G
Time 7.3 hours 4.7 minutes 246λ @ 18 GHz
Incident Wave Incident Wave
93x speedup, 98% less RAM
HFSS-IE HFSS-PO
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 40 November 14, 2012
Fighter Aircraft RCS using PO
15.15 meter 910 λ @ 18GHz
10.325 meter 620 λ @ 18GHz
Incident Wave
Front View
Top View
4.19 meter 252 λ @ 18GHz
Mesh # RAM Elapsed Time
10GHz 5.03 million 15.4 G 27.5 minutes
18GHz 16.19 million 50.6G 174.5 minutes
Blue – 18GHz Red – 10 GHz
10GHz 18GHz
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 41 November 14, 2012
X-band 75-element Array on Fighter Aircraft (HFSS to PO Link)
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 42 November 14, 2012
X-band 75-element Array on Fighter Aircraft (HFSS to PO Link)
Red – Array on Fighter Black – Array Itself
February 23, 2009 Inventory #002593
© 2012 ANSYS, Inc. HFSS 15.0 43 November 14, 2012
Conclusion
• HFSS v15 Hybrid solutions offers best in class solver technology – Integrates the Finite Element Method with 3D Method of Moments – Apply the “best” solver for the individual pieces in the entire 3D System – Improves solver accuracy and speed
• Efficient solution of electrically large structures • Reduces the FEM Volume for speed
• HFSS v15 with HPC runs faster and larger designs – Domain Decomposition increases capacity by distributing the solution across a network
of computers – HPC provides solver enhancements to FEM, HFSS-IE, and HFSS Hybrid solutions
• HFSS-IE v15 improves upon the previous generation solver
– Improved accuracy and speed for electrically large models – Improved communication with MPI – HFSS-IE solver scales to enable simulating multiple antennas distributed across a
platform