The document summarizes recent advances in electromagnetic simulations software FEKO. It describes new solvers added including Finite Difference Time Domain (FDTD) and a hybrid Multilevel Fast Multipole Method (MLFMM)/Physical Optics (PO) method. It also covers extensions to Ray-Launching Geometrical Optics (RL-GO) such as automatic ray launching and curvilinear triangles. Improved interfaces to other tools and future extensions are briefly outlined.

1. Advances in EM Simulations
Dr. Ulrich Jakobus
Vice President – Electromagnetic Solutions
jakobus@altair.com
6 May 2015
ATC 2015, Dearborn, MI, USA

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Contents
• Overview of recent extensions in FEKO:
• Finite Difference Time Domain (FDTD)
• Hybrid MLFMM/PO
• Extensions to Ray-Launching Geometrical Optics (RL-GO)
• New interfaces to other tools
• Outlook into future extensions

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Solvers in FEKO Suite 7.0

4. New FDTD Solver

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FDTD Solver Added to FEKO
• Currently for frequency domain results only
(e.g. broadband studies)
• Native time domain processing for all solvers
in FEKO under development

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FDTD Example: Electromagnetic Pulse
• EMP incident on a two storey building
• Investigate the transient fields caused by the EMP
• Induce an incident plane wave on the building
• Compare MoM (SEP) and FDTD results

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FDTD Example: Electromagnetic Pulse
Despite comparing results from a time and frequency domain method, the
results agree extremely well

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FDTD Example: Electromagnetic Pulse
Field distributions at 30 MHz
FDTDMoM
FDTDMoM

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FDTD Example: Electromagnetic Pulse
Method RAM (GB)
Simulation time
(hours) Hardware
MoM (SEP) 17.84 1.36 parallel 8x cluster
FDTD 1.96 0.18
1x GPU, NVIDIA
Tesla K20c
Computational requirements to simulate the building structure at 30 MHz

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MoM/FEMFDTD
FDTD Example: Human Phantom Modelling
Anatomical head model with 8 tissues simulated at 300 MHz
models provided by humanbodymodels.com, a Simpleware product

11. Iterative Hybrid Method
MLFMM / PO

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Iterative MLFMM/PO
Horn antenna and reflector example
• horn antenna modelled with MLFMM
• reflector modelled with PO
• MLFMM currents labelled 𝐽 𝑀𝑜𝑀
• PO currents labelled 𝐽 𝑃𝑂
MoM region (MLFMM)
𝐽 𝑀𝑜𝑀 = currents on MoM region
PO region
𝐽 𝑃𝑂 = currents on PO region

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Iterative MLFMM/PO: Cassegrain Horn Antenna
MLFMM: horn + sub-reflector
PO: main reflector
~63 λ diameter main reflector

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Iterative MLFMM/PO: Cassegrain Horn Antenna
Solver memory and run-time comparison
Intel® Core™ i7-3820 CPU @ 3.60GHz; 4 parallel processes
A fully coupled MoM/PO solution would have needed 98 GByte!
Run-time [hours]
Peak Memory
[GByte]
MLFMM 0.786 12.4
MLFMM/PO hybrid
(3 iter. mod. YRHS)
0.923 1.26
MLFMM/LE-PO hybrid
(3 iter. mod. YRHS)
0.129 0.43
MoM/PO decoupled 2.3 1.24

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Iterative MLFMM/PO: Cassegrain Horn Antenna

16. RL-GO Extensions
(FEKO Suite 7.0.2 Update
Febr. 2015)

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RL-GO – Automatic Ray Launching
New adaptive ray launching algorithm:
• Implemented for both plane waves and point sources
• The number of source rays to reach convergence is reduced
• Hence, the memory used is reduced and the computation is accelerated
UNIFORM ADAPTIVE

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RL-GO – Automatic Ray Launching
Model
Manual
(u = v = 0.01)
Automatic
Runtime Memory Runtime Memory
Square plate
(90 angles)
71 sec 70.3 MB 8 sec 2.2 MB
Dihedral
(181 angles)
60 sec 35.1 MB 7.2 sec 2.2 MB
Trihedral
(33 freq.)
1.5 min 140.6 MB 2.6 sec 4.4 MB
Cone + Sphere
(181 angles)
24.3 min 17.8 MB 15.7 min 4.7 MB
Ship
(181 angles)
1.2 hours 1.1 GB 8.9 min 281.3 MB

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RL-GO – Automatic Ray Launching
• RCS of an electrically large ship at 1 GHz in HH-pol
• Uniform: 52.88 hours 8.8 GB
• Adaptive: 7.3 hours 2.2 GB

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RL-GO – Ray Tracing Acceleration
• Based on a kd-tree distribution of the RL-GO triangles
• The memory impact and the time to build the kd-tree are very low
• Accelerates the ray-triangle intersection tests using O(M x log N) versus
traditional O(M x N), where M = no. of rays and N= no. of triangles
Triangle
size length
No. of
triangles
Ray tracing: one-
to-one
(sec)
Ray tracing: with
KD-Tree
(sec)
Time to build
KD-Tree
Memory of
KD-Tree
 388 13.2 1.3 0 8 KB
/2 1 546 49.6 1.3 0.003 8 KB
/4 5 972 188.7 1.4 0.016 32 KB
/8 25 040 812.1 1.6 0.085 128 KB
/16 100 550 3 375.4 1.9 0.374 256 KB
/32 410 102 13 535.0 3.0 1.616 512 KB
/64 1 626 321 49 745.5 5.1 6.775 1 MB

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RL-GO – Curvilinear Triangles
• Reflection and transmission over curvilinear surfaces following GO (Geometrical
Optics) reflection and transmission rules
• Detection of caustics
• The number of triangles needed to represent a curved geometry is reduced  ray-
tracing is accelerated
3480 curvilinear triangles
21.2 sec
60240 planar triangles
3.35 min

22. Other New Features

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Interface between FEKO and INSIGHT from MVG
Improved interfaces for near- and far-field data from Sigrity, MVG, CST.
Validation of the FEKO – MVG/INSIGHT link:

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Importing of PCB File Formats
New import file formats
• Gerber
• ODB++
• 3Di
ODB++ imported PCB and simulated currents on PCB with antenna

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Summary & Outlook
Presentation of new features in FEKO Suite 7.0 with subsequent updates.
Selected high level feature issues for FEKO 14.0:
• Extension of curvilinear mesh elements to wires for MoM and MLFMM
• Allow HOBF/MoM in the UTD and RL-GO hybrid methods
• Further RL-GO extensions (saving memory through on the fly computation of
Huygens sources; saving time by combining equivalent sources etc.)
• Frequency domain FDTD extensions (such as multiple configurations, OpenMP
parallelisation for multicore machines, PMC boundaries, zero impedance loads,
implicit wire radius, …)
• Vance braided shield model for cables
• Active RCS calculations (sources other than plane waves in the model)
• Complete the scripting and automation API in CADFEKO
• Lua based macro recorder in CADFEKO
• Improved integration with HyperMesh and HyperStudy
• FEKO LITE to be replaced by Student Edition (with significantly higher limits)
• Drop requirement for admin rights under Windows

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Thank you!
jakobus@altair.com
www.altairhyperworks.com/feko