...from Ohm's law to Snell's law
leaders in rf/microwave solutions and electronics consulting
leaders in rf/microwave solutions and electronics consulting
EM3DS (ElectroMagnetic
3D Simulator)is an integral equation-based full wave simulator, using an
approach called Generalized Transverse Resonance Diffraction (GTRD),
developed by MEM (Microwave and ElectroMagnetics) Research.
Details about the general technique are available in a number of source, including the book
“Advanced Electromagnetic Analysis of Passive and Active Planar Structures”, by T. Rozzi and M. Farina (IEE Press 1999)
and in the paper “A 3-D Integral Equation-Based Approach to the Analysis of Real Life MMICs: Application
to Microelectromechanical Systems”, by M. Farina and T. Rozzi (IEEE MTT December 2001).
This simulator accounts for finite-thickness, finite conductivity real conductors/dielectrics
by using volume currents. The structure is still layered -and defined layer-by-layer, much like a standard process to
realize integrated circuits or printed circuit board- but current induced in conductors appears to be arbitrarily oriented
(Jx, Jy and Jz are always present in the 3D mode; as consequence the total current may have arbitrary orientation even
over sides of a thick conductor). This allows EM3DS to fully model also dielectric discontinuities, including
Dielectric resonators, which are out of the scope of traditional so called 2.5D solvers,
namely solvers modeling either flat planar circuits by exploiting xy currents and vertical conducting posts (vias)
by using z currents alone.
Moreover, the ability to handle conductor thickness, which is usually not very important in standard PCB design where
substrate losses are dominant and the structures are very large with respect to the metallization thickness, it may
fundamentally affect results in MMIC design, where strips may be a few microns thick and wide.
Metal thickness is also important in waveguide filters: consider e.g. that in single cavity WR90 resonator,
neglecting the iris thickness may produce a resonant frequency shift of over 5%.
EM3DS is mainly aimed at the analysis of planar structures, but due to its 3D nature it may be used also to
address some other problems, like e.g. the modeling of some class waveguide filters with arbitrary thick, possibly
lossy, irises.
Actually EM3DS embodies in fact 2 EM Solvers – 2.5D and 3D. Which solver to use is rested
upon the designer’s choice and is a simple click to shift the mode of operation. It means that by simple click onto
your 3D structure, you obtain 2.5D geometry and you can simulate as 2.5D and compare with your 3D simulation.
The speed is increased in 2.5D mode by a factor varying from 50% up to more than 300%: the more the structure is complex,
the larger is the time saved. The 2.5D mode comes as a limit of the 3D formulation, keeping several attracting
capabilities of the 3D mode.
EM3DS comes with a complete set of tools. The most important is maybe the panel for global
parameters/variables: the panel allows you to define variables, and to parameterize the
geometrical features of your objects. This means that you can modify and optimize your design
without painfully entering new dimensions shape by shape. The optimization can either be manual (the designer does the work)
or exploit the embedded optimizer. Variables can be modified also accessing a
"tuner", a set of sliders varying those variable indicated as tunable in the optimizer panel.
Variables can also be accessed through a pascal "script", namely by writing a pascal code
directly in EM3DS.
As to the speed, EM3DS always performed very well thanks to its Asymptotic Estimator, which
performs a full simulation only at the first frequency point, while reusing most of the information for the analysis
at the remaining frequency points. Moreover, since version 7 is available a new powerful device,
SmartFIT: this algorithm adaptively drives the EM solver, generating a frequency list within the user-selected band.
At the end it estimate the response all over that band, in tents or hundreds of points. Of course it is possible to exploit
a rational interpolator even in post-processing, but without the same guarantee to get good results.
The new release, version 9, adds several completely new features, such as
internal planar ports, antenna functions (namely sense layer to see the E-field and to evaluate radiated far field,
both in standard polar diagrams, or in 3D surfaces), object oriented pascal scripting, tuner,
enhanced editing etc.
Since ver 6.0 EM3DS was the first tool allowing the full-wave modeling of FETs in linear
regime: this is accomplished through the insertion of distributed controlled current sources. EM3DS 6.0 provides for
the materials’ constitutive parameters to be frequency dependent, and may further be specified by the user through
analytical expressions (formulas). Every parameter in EM3DS can conveniently be input as a
valid algebraic expression, (for instance: sin(3.5)), and is fully evaluated (calculated) by EM3DS, thus facilitating
the overall process and avoiding using calculators.
Unlike some other commercially available tools, when entering the geometry, EM3DS does not pose
any requirement on the grid.
The only event when grid is desirable, and in fact EM3DS can make use of it, is during the drawing, where it offers
additional flexibility.
As stated above, EM3DS comes integrated with several tools, aimed to ease interfacing with other CAE tools. As to the
pre-processing step, filters allowing importing GDSII and DXF (as well as general
bitmaps) are available. The post-processor includes a Spice Model Extractor, a simple
Linear Circuit Simulator, tools for saving animations (GIF, AVI), link to AVI files via
multimedia documents, exporting graphs (plots, Smith Charts), data files
(Touchstone), to see the interaction between a user-defined magneto-static field
and RF currents flowing across an object etc.
Nonetheless for MEM Research it is imperative to look for partnerships in order to better exploiting the EM3DS power.
This is why in the past EM3DS 5 was also fully integrated as Electromagnetic Module in the multi-physic package by
Corning Intellisense, Intellisuite®.
Currently, EM3DS is companion of CoventorWareTM, by Coventor, leading company in the MEMS
software development: EM3DS was carefully selected by Coventor thanks to its remarkable achievements.
By the same token EM3DS has the ability to be accessed directly from the AWR Microwave Office
(since version 6 of MWO) suite. This means that AWR’s customers are able to see EM3DS as an electromagnetic
engine, still using Microwave Office editor and post-processing capabilities.
