advances in em simulations

Advances in EM Simulations

Dr. Ulrich Jakobus

Vice President – Electromagnetic Solutions

[email protected]

6 May 2015

ATC 2015, Dearborn, MI, USA

Copyright © 2015 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.

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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

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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Despite comparing results from a time and frequency domain method, the

results agree extremely well


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Field distributions at 30 MHz

FDTDMoM

FDTDMoM


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Method RAM (GB)

Simulation time

(hours) Hardware

MoM (SEP) 17.84 1.36 parallel 8x cluster

FDTD 1.96 0.181x GPU, NVIDIA

Tesla K20c

Computational requirements to simulate the building structure at 30 MHz


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Mo

M/F

EM

FD

TD

FDTD Example: Human Phantom Modelling

Anatomical head model with 8 tissues simulated at 300 MHz

models provided by humanbodymodels.com, a Simpleware product

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 𝐽𝑀𝑜𝑀

• PO currents labelled 𝐽𝑃𝑂

MoM region (MLFMM)𝐽𝑀𝑜𝑀 = currents on MoM region

PO region𝐽𝑃𝑂 = 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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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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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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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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• 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 triangles21.2 sec

60240 planar triangles3.35 min

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!

[email protected]

www.altairhyperworks.com/feko

advances in em simulations

Documents

altair engineering

fdtd results

reflector po

po mlfmm currents

momfemfdtd fdtd example

mlfmm reflector

po currents

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