1. Software Tools for Microwave Research, Design, and Education
Dejan V. Tošić
Milka Potrebić
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

5. 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

6. 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

7. 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

8. Who is using microwave software tools ?
Engineers
Practitioners
Researchers
Academia

9. AWR Microwave Office (MWO)

10. 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

11. 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

12. 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

13. Optimization
Optimizer for circuit model parameters without possibility to optimize physical structure
Tuning – manual optimization

14. Transmission Line Calculator

15. Filter Synthesis Wizard

17. What is WIPL-D Microwave?
New design and simulation tool for microwave projects involving microwave circuits, components, and antennas
Full wave 3D EM solver

18. 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

19. Defining structures by means of (non)uniform grids

20. Advanced modeling concepts
Using symmetry to facilitate analysis
Modeling of the end effect and feed area for thick wires
Coaxial line excitation

21. Edging & De-embedding
Modeling of layered structures
De-embedding of circuit parameters from the 3D EM analysis
Taking the edge effects
into account

22. 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

23. Technology-related palettes
Microstrip
Not available in MWO double step & patch antenna
Coaxial
Rectangular
Special components coaxial taper, band, step, gap, T-junction & cross
Special components E- and H-post, E- and H-band, ET- and HT-junction, E- and H- coupled waveguides, rectangular horn antenna & magic tee junction
Transitions
Special components transitions from coaxial to rectangular or microstrip technology

24. 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

25. 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

26. 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 characterization: ideal or analytical or 3D electromagnetic
Analytical (Recommended):

27. Versatile input options
Characteristic impedance &
Normalized length
Physical
dimensions

29. 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

30. 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

31. 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

32. Circuit, Physical Layout, and Planar EM model

33. Circuit libraries Online

34. Example component parameters
Microstrip Transmission Line, Physical Length - MSTRL

35. 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

36. Meshing
Fixed meshing with edge meshing
Adaptive meshing

37. 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

38. Filter Design Wizard

39. Transmission Line Calculator

40. Microstrip lowpass filter
Simulation example
Microstrip lowpass filter

41. Specification
Source/load impedance

42. Realization
Seven-pole lowpass filter with Chebyshev response

43. 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

44. 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)

45. Example in MWO
Schematic
2.5D model

46. Example in WIPL-D Microwave
Schematic
3D model

47. Example in Ansoft Designer
Schematic
3D model

48. Simulation results (1)
Ansoft Designer
WIPL-D MW
MWO

49. Simulation results (2)
WIPL-D MW
MWO
Ansoft Designer

50. Simulation results (3)

51. Amplitude difference measure (of the frequency response)
3D WIPL-D model & 2.5D MWO model

52. and potential disadvantages
Benefits
and potential disadvantages

53. 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

54. 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

55. 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

56. 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

57. 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

58. 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

59. 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

60. 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

61. 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

62. Potential disadvantages
No transition components (release 2004)
Might be over-sophisticated for students
Comparatively high prize

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

64. Conclusion (1) We have evaluated and compared microwave 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

65. 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