Read Use of HFSS as integral part of efficient design environment for waveguide components text version

Use of HFSS as integral part of efficient design environment for waveguide components

Jan Kocbach, Kjetil Folgerø

Nera Networks, Norway

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J. Kocbach and K. Folgerø

Outline

· Nera products and needs · Design environment

­ Overview of design environment ­ Role of HFSS in design environment ­ HFSS ­ Matlab interaction

· Applications and examples · Summary

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J. Kocbach and K. Folgerø

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

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J. Kocbach and K. Folgerø

Passive microwave components at Nera

· Design wide range of different passive microwave components

­ Waveguide filters ­ OMTs, Polarizators ­ Microstrip-to-waveguide and Microstrip-to-coax transitions ­ Microstrip/stripline filters

· Many frequency variants for each component

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J. Kocbach and K. Folgerø

Passive microwave components at Nera

· 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

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J. Kocbach and K. Folgerø

Design Environment

Waveguide components / Passive microwave components

STL export SAT import via translator

CAD/CAE Pro Engineer

3D simulator

Mode matching software

HFSS

Via macros

Via netlist files

Control software

Control: Matlab

Matlab control software also communicates with other 3D and 2.5D simulators used at Nera

­ Mode matching

· · · · Very fast solving Optimization with >10.000 iterations Large library of geometries Drawback: Not arbitrary geom

­ Full 3D EM

· Arbitrary geometries · possible to view fields/animations · Drawback: Slow (compared to Mode matching)

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J. Kocbach and K. Folgerø

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

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J. Kocbach and K. Folgerø

Matlab ­ HFSS interaction

· Defined "Meta-language" for HFSS in Matlab

h_addmaterial h_box h_cyl h_rectangle h_rectsweep h_iris h_polysweep h_definesolution h_init h_newcoordsys h_plus h_setboundary h_setcoordsys h_setport h_subtract h_unite h_runhfss Add material Draw box Draw cylinder Draw rectangle Sweep rectangle Draw iris Sweep polygon Define solution Initialize New coordinate sys Add two HFSS vars Set boundary Set coordinate sys Set port Subtract objects Unite objects Run HFSS Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: Input: struct with material parameters geometry vectors geometry vectors geometry vectors geometry vectors struct with variables vector with points + sweep struct with solution details none scalars theta/phi, coordsys name strings/operators string, type of BC string, name of coordinate system string, object name string, object names string, object names struct with all info

· ·

Typical analysis functions:

­ Repeated calling of setup/drawing-functions and h_runhfss function

Simple analysis functions ­ short development time

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J. Kocbach and K. Folgerø

Matlab ­ HFSS interaction

· "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); end sp=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);

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J. Kocbach and K. Folgerø

Matlab ­ HFSS interaction

· Definition of sample function h_box

function [sp]=h_box(basevc,sizevc,sp) <--- lines omitted ---> Set only one variable if sp.slipangle~=0 to use slip angles [sp]=h_box_slipa(basevc,sizevc,sp); else <--- lines omitted ---> 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 ')']; <--- lines omitted ---> end Global settings

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J. Kocbach and K. Folgerø

Matlab ­ HFSS interaction

· Matlab applied as control software

­ Partly common control functions for HFSS and other simulators

·

Circuit models implemented in Matlab

­ HFSS and other 3D/Mode matching programs applied for training of circuit model ­ Trained circuit model used for very fast tolerance analysis ­ Circuit model used for intelligent filter design in conjunction with HFSS 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(?)

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J. Kocbach and K. Folgerø

Matlab ­ HFSS interaction

· Optimization

­ Optimization done by repeated calling of HFSS using different 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 defines problem

·

Simplified buildup of complex models

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J. Kocbach and K. Folgerø

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] Input: Center frequency, bandwidth, ripple & filter order Output: Filter dimensions, S-parameters

­ Automated design procedure using Matlab + HFSS

[1] Folgerø, K. (Nera Research), Step-by-step procedure for design of waveguide filters with HFSS, Ansoft HFSS User Workshop, Los Angeles, January 2001

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J. Kocbach and K. Folgerø

Applications (I)

· Design of waveguide filter with slip angles

Circuit model gives ideal S-parameter value for each coupling

S21 = -5.1 dB

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J. Kocbach and K. Folgerø

Applications (I)

· Design of waveguide filter with slip angles

Vary iris width

S21 [dB]

-4 -6 -8 -10 -12 -14 -16 -18 1 2 3 4

"Tune" single coupling

Coupling 1

Simulation Circuit model 5 6

Iteration number (varying iris width)

S21 = -5.1 dB

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Applications (I)

· Design of waveguide filter with slip angles

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J. Kocbach and K. Folgerø

Applications (I)

· Design of waveguide filter with slip angles

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J. Kocbach and K. Folgerø

Applications (I)

· Design of waveguide filter with slip angles

S-parameters [dB]

Simulation of complete filter with slip angles

f [GHz]

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J. Kocbach and K. Folgerø

Applications (I)

· Measurements: Waveguide filter with slip angles

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J. Kocbach and K. Folgerø

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

0

-10

-20 S (dB) Without slip-angle With slip-angle* -30

-40

-50 18 20 22 24 26 frequency (GHz) 28 30 32

*Final iteration regarding normal plane for slip angles

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J. Kocbach and K. Folgerø

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)

+

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J. Kocbach and K. Folgerø

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]

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J. Kocbach and K. Folgerø

Applications (V)

· Rectangular dual mode filter

­ Blue line: HFSS. Red line: ModeMatching ­ HFSS simulation to visualize fields

S-parameters [dB]

f [GHz]

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J. Kocbach and K. Folgerø

Applications (V)

· Rectangular dual mode filter

­ Very good correspondence between simulations and measurements ­ No tuning

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J. Kocbach and K. Folgerø

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

·

Information

Use of HFSS as integral part of efficient design environment for waveguide components

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