Software Tools for Microwave Research, Design, and Education

1
Software Tools for Microwave Research, Design,
and Education

• Dejan V. Tošic
• Milka Potrebic
• School of Electrical Engineering
• Belgrade

2
Overview

• Introduction
• Microwave Office
• WIPL-D Microwave
• Ansoft Designer
• Simulation example
• Benefits
• Conclusion

3
Objective

• Compare software tools for microwave circuit
  simulation from the research, design, and
  educational view point
• Identify a candidate tool for each category
• Highlight teaching aspects

4
Considered Microwave Tools

• AWR Microwave Office MWO
• WIPL-D Microwave
• Ansoft Designer

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Introduction (1)

• As we move towards a learner-oriented,
  self-paced, asynchronous system for higher and
  continuing education, the traditional
  course-based curriculum structure must be
  examined for its efficiency
• Courses can be restructured into primary concept
  modules that are interlinked to reflect the
  logical development of knowledge in the domain of
  the discipline being studied

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Introduction (2)

• With the wireless revolution, brought on mostly
  by cellular radio technologies, microwave
  applications have come to dominate the industry
• Cost, time to market, and manufacturing capacity
  are much stronger influences within the microwave
  engineering
• Cost versus performance will always be a
  trade-off within any engineering project,
  however, the weighting coefficients have shifted
  

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Why is it important ?

• Software tools are indispensable in microwave
  engineering, so R D, design, and the
  corresponding courses should always address
• computer aided design
• simulation prior to manufacturing

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Who is using microwave software tools ?

• Engineers
• Practitioners
• Researchers
• Academia

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AWR Microwave Office(MWO)
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What is MWO?

• Popular microwave software environments in both
  academia and industry
• Professional design tool
• Linear nonlinear solution for microwave hybrid,
  module and MMIC design
• Includes linear, harmonic-balance, time-domain,
  electromagnetic (EM) simulation, physical layout
• Frequency domain simulator

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2.5D EM Layered Structures

• EM simulation is based on 2.5D solver for
  layered structures (microstrip filters
  antennas) with predefined objects (rectangle,
  polygon, path, ellipse, drill hole, edge port,
  via, ...)
• Only automatic mashing in three levels

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Layout view

• Layout view can be generated from the schematic
  to take into account mutual coupling,
  parasitics, discontinuities,
• Layout structure can be analyzed by 2.5D EM solver

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Optimization

• Optimizer for circuit model parameters without
  possibility to optimize physical structure
• Tuning manual optimization

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Transmission Line Calculator
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Filter Synthesis Wizard
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What is WIPL-D Microwave?

• New design and simulation tool for microwave
  projects involving microwave circuits,
  components, and antennas
• Full wave 3D EM solver

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Features

• Predefined circuit components arbitrary
  composite metallic and dielectric structures
  defined by user
• Circuit parameters of the included 3D EM
  components are computed on-the-fly
• Intended for engineers, practitioners,
  researches, academia, and as a teaching tool for
  microwave engineering curricula

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Defining structures by means of (non)uniform grids
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Advanced modeling concepts

• Using symmetry to facilitate analysis

Modeling of the end effect and feed area for
thick wires

• Coaxial line excitation

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Edging De-embedding

• Modeling of layered structures

• De-embedding of circuit parameters from the 3D
  EM analysis

• Taking the edge effects
• into account

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Ideal Palette
Contains all basic components for introductory
microwave courses
short circuited end open-circuited
end amplifier ideal transformer
circulator symmetric power splitter quadrature
hybrid coupler
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Technology-related palettes
Microstrip
Coaxial
Not available in MWOdouble step patch antenna

• Rectangular

Special componentscoaxial taper, band, step,
gap, T-junction cross
Special componentsE- and H-post, E- and H-band,
ET- and HT-junction, E- and H- coupled
waveguides, rectangular horn antenna magic tee
junction
Transitions
Special componentstransitions from coaxial to
rectangular or microstrip technology
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Electrical length of ports

• Ports of each component can be electrically
  extended equivalent transmission lines can be
  added to ports
• Schematic can contain fewer elements and one can
  experiment with shifting reference planes which
  define component ports

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3D EM models

• 3D EM modeling provides predefined objects
  dielectric domains, wires, plates,

• sphere, circle, reflector, and body of
  revolution
• transition between two coaxial cables
• half-sphere with a hole
• ring with circular cross
• ring with a square cross sections

• Symbolic parameters of 3D EM models can be
  optimized

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Ideal, analytical, and 3D EM component
characterization

• 3D EM analysis enables to explore differences
  between the results generated by analytical
  closed-form equations and accurate EM numerical
  simulations
• 3D EM models can be made when the component
  parameters are out of the range over which the
  analytical model is valid
• Multiple component characterizationideal or
  analytical or 3D electromagnetic

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Versatile input options
Characteristic impedance Normalized length
Physical dimensions
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What is Ansoft Designer ?
High-performance RF/mW Design Analog/RFIC
Verification

• Ansoft Designer provides an integrated
  schematic and design management front-end
  for complex analog, RF and mixed-signal
  applications
• By leveraging advanced electromagnetic-field
  simulators dynamically linked to powerful
  circuit and system simulation, Ansoft Designer
  enables engineers to design, optimize and
  validate component, circuit, and system
  performance long before building a prototype
  in hardware

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Features (1)

• Digital-communication-system simulation
• Nonlinear circuit simulation, frequency domain,
  and transient
  analyses
• Planar 3D EM simulation
• Integrated IC and PCB layout editor with Java and
  Visual Basic scripting
• Impulse invariance convolution engine
• Swept parameter analysis

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Features (2)

• Support of parameterized subcircuits, global
  variables, and parameter scoping
• Support of compiled and interpretive
  user-defined models (UDMs SDDs)
• Design utilities, including real-time tuning
  filter and TRL synthesis and load-pull analysis
• Advanced design environment with dynamic project
  manager and solution caching
• Dynamic link with HFSS, 3D electromagnetic
  structure simulator

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Circuit, Physical Layout, and Planar EM model
Circuit
Physical Layout
Planar EM model
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Circuit libraries
Online
http//www.ansoft.com/products/hf/ansoft_designer/
designkits.cfm
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Example component parameters
Microstrip Transmission Line, Physical Length -
MSTRL
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Planar EM model

• Full 3D EM simulation
• Predefined objects circle, rectangle, arc,
  line, polygon, void, hole, via (2.5D or 3D),
  cavity,
• Symbolic parameters of 3D EM models can be
  optimized
• Estimate Module Planar EM Calculator
• Microstrip line
• Quarter-wave transformer
• Tuning stub
• Rectangular patch
• Circularly polarized (CP) patch

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Meshing

• Fixed meshing with edge meshing
• Adaptive meshing

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Optimization
to determine how each design variation
affects the performance of the design
Optimetrics changes the design parameter values
to meet the goal
to determine the sensitivity of the design to
small changes in variables
Optimetrics determines the distribution of a
design's performance
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Filter Design Wizard
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Transmission Line Calculator
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Simulation example

• Microstrip lowpass filter

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Specification
Source/load impedance
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Realization
Seven-pole lowpass filter with Chebyshev response
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Implementation

• Microstrip technology, fabricated on substrate
  with relative dielectric constant
  and thickness without losses
• Open-circuited stubs implementation is chosen
  with high impedance lines as and
  a line width
• Open-circuited stub has a line width

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Simulation models

• An important issue is to demonstrate
• differences between various simulation models
• Analytical
• 2.5D EM (MWO)
• 3D EM (WIPL-D Microwave, Ansoft Designer)

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Example in MWO
Schematic
2.5D model
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Example in WIPL-D Microwave
Schematic
3D model
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Example in Ansoft Designer
Schematic
3D model
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Simulation results (1)
AnsoftDesigner
WIPL-D MW
MWO
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Simulation results (2)
WIPL-D MW
MWO
AnsoftDesigner
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Simulation results (3)
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Amplitude difference measure (of the frequency
response)
3D WIPL-D model 2.5D MWO model
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Benefits

• and potential disadvantages

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Benefits (1)

• WIPL-D Microwave is a candidate tool for
  implementing efficient microwave education
• From the teaching view point, it has the
  following benefits
• Contains all components and microwave circuit
  models needed for undergraduate microwave courses
• Ideal microwave elements are grouped into a
  separate toolbar, so the student easily builds
  idealized microwave circuits

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Benefits (2)

• Numerous teaching examples are available and are
  based on the widely used textbooks adopted in
  many microwave courses
• Comprehensive review of microwave circuit basics
  is provided, so students can quickly review the
  scattering matrix properties, element
  definitions, and other background lessons
• Full wave 3D EM analysis is available so the
  student can compare the results generated by
  analytical closed-form equations and accurate
  EM numerical simulations

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Benefits (3)

• Multiple component characterization is provided
  so the student can specify a component as ideal
  or analytical or 3D electromagnetic
• Technology-related components have integrated
  parameters and technology descriptors
• Arbitrary metallic-dielectric structures can be
  characterized by, for example, scattering
  parameters and incorporated into the schematic
  when the components parameters are out of the
  range over which the analytical model is valid

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Benefits (4)

• WIPL-D optimizer can optimize all schematic
  parameters including the parameters of the
  embedded 3D EM models
• Ports consist of transmission lines with
  adjustable length that can be set to an
  arbitrary value, so a schematic can be built
  with fewer elements
• WIPL-D is affordable for students because of its
  low price

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Potential disadvantages

• Time response can not be computed
• Nonlinear circuits can not be simulated
• Subcircuits are not available
• Graphical presentation of the simulation results
  by default smoothes data (fitting tool) that
  might lead to unexpected curves (peaks) this
  might confuse students and cause them to
  misinterpret the results

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Benefits

• Provides nonlinear microwave circuits and systems
• Physical layout representation is assigned to
  each component in a schematic, but this option
  does not always give correct layout
• Arbitrary 2.5 D EM multi-layer structures can be
  incorporated into the schematic
• MWO can not optimize physical structure, but it
  has a powerful manual and automatic optimizer for
  circuit model parameters
• Computes the time-domain response
• Subcircuits can be used in the schematic
  realization
• Filter design wizard

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Potential disadvantages

• Numerous components and their grouping sometimes
  might be confusing for undergraduate students
• Layered EM structures can be modeled but cannot
  be optimized
• Abundant advanced examples may not be suitable
  for undergraduate teaching process
• MWO is not so affordable for students because of
  its high price

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Benefits (1)

• Provides nonlinear microwave circuits and systems
• Physical layout representation is assigned to
  each component in a schematic and it can be
  automatically exported to planar electromagnetic
  model
• Full wave 3D EM analysis with possibility to
  incorporate arbitrary 3D EM multi-layer
  structures into the schematic
• Ansoft Designer has a powerful manual and
  automatic optimizer for circuit and 3D EM model
  parameters

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Benefits (2)

• Multiple component characterization is provided
  as analytical or 3D electromagnetic
• Technology-related components have predefined
  global substrates
• Computes the time-domain response
• Subcircuits can be used in the schematic
  realization
• Calculators
• EM estimator
• Transmission line calculator
• Filter design wizard

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Potential disadvantages

• No transition components (release 2004)
• Might be over-sophisticated for students
• Comparatively high prize

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WIPL-D
MWO
Feature
Ansoft
Yes
Yes
No
Full 3D simulation
2.5D 3D
Basic Complex
Basic
Basic
Predefined object
Uniform
Uniform/Non-uniform grid (EM model)
Uniform Non-uniform
Uniform
Yes
Symbolic variables
Yes
No
Yes
No
Optimization
Yes
Yes
No
Symmetry planes
No
Yes
Automatic check
Yes
Yes
Yes
Yes
Yes
De-embedding
Automatic
Automatic Manual
Automatic
Edging
EM estimator
No
No
Yes
No
Yes
Yes
Nonlinear components
Circuits Systems
Yes
Only ideal
Transitions
Only ideal
Yes
Yes
Symbolic variable
Yes
Yes
Circuit optimization
Yes
Yes
No
Yes
Yes
Layout (implementation) view
Yes
Functional blocks (systems)
No
Yes
Transmission line calculator
Yes
Yes
Basic
Filter design wizard
Yes
Yes, complex
No
Measures
Yes
Yes
Not all, such as G,H, ABCD
S, Y, Z, G, H, ABCD, V, I, P
No
Yes
Yes
Time domain reflectometry
Near Far
Far
Near/Far field radiation
Near Far
Cost
Low
Very high
Very high
Price
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Conclusion (1)

• We have evaluated and comparedmicrowave software
  tools
• Two professional tools
• Microwave Office (7.0 beta 2006)
• Ansoft designer (release 2004)
• New software tool WIPL-D Microwave (December
  2005)
• Research, design, and teaching aspects were
  considered

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Conclusion (2)

• WIPL-D Microwave Teaching, Introductory
  microwave courses
• Ansoft Designer
• The most versatile from all view points
• Microwave Office The most convenient user
  interface, Suitable for research, design, and
  advanced microwave courses