Use of HFSS as integral part of efficient design ...web.ift.uib.no/~jankoc/publ/nera/ansoft_converge_kocbach.pdf · Use of HFSS as integral part of efficient design environment for

Use of HFSS as integral part of

efficient design environment

for waveguide components

Jan Kocbach, Kjetil Folgerø

Nera Networks, Norway

J. Kocbach and K. FolgerøAnsoft Converge 2005 - Slide 2

Outline

• Nera products and needs

• Design environment

– Overview of design environment

– Role of HFSS in design environment

– HFSS – Matlab interaction

• Applications and examples

• Summary


Nera Products

• Terrestrial (Nera Networks)– Long haul networks (4-11 GHz)

– Fixed wireless access (6-40 GHz)

– Mobile infrastructure (6-40 GHz)

• Satellite (Nera Satcom)

– Mobile satellite communication solutions

– Broadband satellite communication solutions


Passive microwave components at Nera

• Design wide range of different passive microwave components– Waveguide filters

– OMTs, Polarizators

– Microstrip-to-waveguide and Microstrip-to-coaxtransitions

– Microstrip/stripline filters

• Many frequency variants for eachcomponent


• Need efficient and versatile design environment

– Accurate and flexible full 3D tool for

• complex structures

• final design phase & field analysis

– Fast tool for

• simple structures & initial design of more complex structures

• work on design methods

– ”Push-button” design

• fast design of frequency variants

• short design cycles

Passive microwave components at Nera


Design Environment

Control: Matlab

HFSS

STL export

SAT import

via translator

Via netlist

files Control software

3D simulator

Waveguide components / Passive microwave components

– Full 3D EM

• Arbitrary geometries

• possible to view fields/animations

• Drawback: Slow(compared to Mode matching)

– Mode matching

• Very fast solving

• Optimization with >10.000 iterations

• Large library of geometries

• Drawback: Not arbitrary geom

Via macros

Mode matching

software

Pro Engineer

CAD/CAE

Matlab control software also

communicates with other 3D

and 2.5D simulators used

at Nera


Matlab – HFSS interaction

• Our approach based on HFSS v9

– Interface to HFSS from Matlab

1. Make macro file using Matlab function

2. Matlab function starts HFSS with /RunScriptAndExit

3. Matlab function reads ”.tab” or ”.nmf” file into Matlab

• As of HFSS v10

– COM engine for Matlab-HFSS interaction

– Very similar program buildup - even better interaction possible



• Defined ”Meta-language” for HFSS in Matlab

• Typical analysis functions:

– Repeated calling of setup/drawing-functions and h_runhfss function

• Simple analysis functions – short development time

h_addmaterial Add material Input: struct with material parameters

h_box Draw box Input: geometry vectors

h_cyl Draw cylinder Input: geometry vectors

h_rectangle Draw rectangle Input: geometry vectors

h_rectsweep Sweep rectangle Input: geometry vectors

h_iris Draw iris Input: struct with variables

h_polysweep Sweep polygon Input: vector with points + sweep

h_definesolution Define solution Input: struct with solution details

h_init Initialize Input: none

h_newcoordsys New coordinate sys Input: scalars theta/phi, coordsys name

h_plus Add two HFSS vars Input: strings/operators

h_setboundary Set boundary Input: string, type of BC

h_setcoordsys Set coordinate sys Input: string, name of coordinate system

h_setport Set port Input: string, object name

h_subtract Subtract objects Input: string, object names

h_unite Unite objects Input: string, object names

h_runhfss Run HFSS Input: struct with all info



• ”Meta-language” - code example:

% Define variables

a=10.668;b=4.318;lin=6;

liris=[1.3 1.5 1.3];

airis=[6.5 6 6.5];lres=[6.3 6.3];

% Draw geometry

sp=h_init;sp=h_box({0 0 0},{lin a b},sp);

for i=1:length(liris)-1

sp=h_box({sp.x 0 0},{liris(i) airis(i) b},sp);sp=h_box({sp.x 0 0},{lres(i) a b},sp);

endsp=h_box({sp.x 0 0},{liris(end) airis(end) b},sp);

sp=h_box({sp.x 0 0},{lin a b},sp);

% Define ports

sp=h_rectangle({sp.x 0 0},{0 a b},sp);sp=h_setport(sp.last_obj,sp);

sp=h_rectangle({0 0 0},{0 a b},sp);sp=h_setport(sp.last_obj,sp);



• Definition of sample function h_box

function [sp]=h_box(basevc,sizevc,sp)

<--- lines omitted --->

if sp.slipangle~=0

[sp]=h_box_slipa(basevc,sizevc,sp);

else


sp.cmd{end+1}=[...

'oEditor.CreateBox Array("NAME:BoxParameters", _\n' ...

'"XPosition:=", ' h_tostr(basevc{1}) ', _\n' ...

'"YPosition:=", ' h_tostr(basevc{2}) ', _\n' ...

'"ZPosition:=", ' h_tostr(basevc{3}) ', _\n' ...

'"XSize:=", ' h_tostr(sizevc{1}) ', _\n' ...

'"YSize:=", ' h_tostr(sizevc{2}) ', _\n' ...

'"ZSize:=", ' h_tostr(sizevc{3}) '), _\n' ...

'Array("NAME:Attributes", "Name:=", "' name '", _\n' ...

'"Flags:=", "", "Color:=", "' simpar.curr_color '", _\n' ...

'"Transparency:=", ' num2str(simpar.curr_transparency) ' _\n'...

' , "PartCoordinateSystem:=", "Global", _\n' ...

'"MaterialName:=", "' simpar.curr_mat '", _\n' ...

'"SolveInside:=", ' simpar.solve_inside ')'];


end

Set only one variable

to use slip angles

Global settings



• Matlab applied as control software

– Partly common control functions for HFSS and othersimulators

• Circuit models implemented in Matlab

– HFSS and other 3D/Mode matching programsapplied for training of circuit model

– Trained circuit model used for very fast tolerance analysis

– Circuit model used for intelligent filter design in conjunction withHFSS and/or other 3D/Mode matching programs

– Applied for automatic and reliable design procedures

• Cascade coupling of S-pars from HFSS/Other simulators

– similar functionality to Ansoft Designer(?)



• Optimization

– Optimization done by repeated calling of HFSS usingdifferent Matlab optimizers

• Tolerance analysis & sweeps

– Tolerance analysis & sweeps with arbitrary distributions by repeated calling of HFSS

• Documentation

– Automatic documentation of HFSS simulations from Matlab

– Simple text-file with ”meta-language” commands definesproblem

• Simplified buildup of complex models


Applications (I)

• Design of waveguide filter with slip angles

– Full 3D tool required for simulations due to slip angles

– Fast & predictable design possible using step-by-step procedure

• No optimization in 3D tool required

• Basic Theory described in [1]

– Automated design procedure using Matlab + HFSS

• Input: Center frequency, bandwidth, ripple & filter order

• Output: Filter dimensions, S-parameters

[1] Folgerø, K. (Nera Research), Step-by-step procedure for design of waveguide filters with HFSS,

Ansoft HFSS User Workshop, Los Angeles, January 2001


Applications (I)


S21 = -5.1 dB

Circuit model gives ideal S-parameter

value for each coupling


Applications (I)


1 2 3 4 5 6

-18

-16

-14

-12

-10

-8

-6

-4

SimulationCircuit model

Iteration number

S21[dB]

Coupling 1

S21 = -5.1 dB

Vary iris width

(varying iris width)

”Tune” single coupling


Applications (I)



Applications (I)



Applications (I)


f [GHz]

S-parameters[dB]

Simulation of complete filter

with slip angles


Applications (I)

• Measurements: Waveguide filter with slip angles


Applications (II)

• OMT with slip angles– Nominal version without slip angles optimized using ModeMatching simulator

– Exported from ModeMatching simulator to ProEngineer

– Slip angles + some other changes applied in ProEngineer

– Imported from ProEngineer to HFSS

– Some iterations with varying normal plane for slip angles

18 20 22 24 26 28 30 32

-50

-40

-30

-20

-10

0

frequency (GHz)

S (dB) Without slip-angle

With slip-angle*

*Final iteration regarding normal plane for slip angles


Applications (III)

• Composite structure: OMT + 2 filters

– All components simulated individually in HFSS with slip angles

– Cascade coupling of S-parameters done in Matlab(would also be possible in Ansoft designer)

– Tuning of waveguide lengths between components

– Tolerance analysis for filters without slip angles (ModeMatching)

– Cascade coupling of S-parameters done in Matlab

• OMT with slip angles (nominal)

• filter without slip angles (100 iterations each)

+


Applications (IV)

• Microstrip-to-waveguide transition

– Large number of frequency variants needed

– Problem setup, optimization, tolerance analysis done automatically from Matlab

S-parameters[dB]

f [Hz]


Applications (V)S-parameters[dB]

f [GHz]

• Rectangular dual mode filter

– Blue line: HFSS. Red line: ModeMatching

– HFSS simulation to visualize fields


Applications (V)

• Rectangular dual mode filter

– Very good correspondence between simulations and measurements

– No tuning


Summary

• HFSS central part of effective design environment for waveguide components

• Key points

– ”Meta-language” for HFSS

– Repeated calling of HFSS from Matlab

– Common control functions for HFSS and other tools

– Reliable and repeatable design – aided by circuit models

– Automatic design cycles

Documents

Use of HFSS as integral part of efficient design ...web.ift.uib.no/~jankoc/publ/nera/ansoft_converge_kocbach.pdf · Use of HFSS as integral part of efficient design environment for