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Modeling >> Passive Devices >> What is full-wave EM solver?
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Message started by Roger on Sep 15^th, 2004, 9:21am

Title: What is full-wave EM solver?
Post by Roger on Sep 15^th, 2004, 9:21am

Hi all,
Could anybody explain the difference between 3D & full-wave EM solver ?

What are the advantages and disadvantages ?

You may tell me the good website for reference.

Thanks very much.

Roger

Title: Re: What is full-wave EM solver?
Post by Fei on Sep 23^rd, 2004, 9:11am

3D EM simulator include:
1). Full wave simulators: HFSS(Frequency domain FEM based) and other FDTD based tool;
2). Quasi-static tool: Q3D of Ansoft.

Chack Ansoft.com

Title: Re: What is full-wave EM solver?
Post by Frank Wiedmann on Sep 24^th, 2004, 12:02am

Unlike quasi-static solvers, full-wave solvers take into account all terms of Maxwell's equations and thus also account for effects like radiation. There are 3D solvers like HFSS from Ansoft and planar or 2.5D solvers like Momentum from Agilent (which also includes a quasi-static solver). Planar solvers are usually much faster than 3D solvers but can only be used for a limited set of geometries. Quasi-static solvers are the fastest of all but do not take into account all effects. They usually give acceptable results for electrically small circuits (size is only a small fraction of the wavelength). A pretty good planar solver can be downloaded for free from http://www.sonnetusa.com.

Title: Re: What is full-wave EM solver?
Post by Roger on Oct 12^th, 2004, 9:25am

Hi all,
Thanks for the answer.
I am not quite understand the difference among 3D, 2.5D, and 2D EM solver. Could anybody explain this ? What are the limitations for these kinds of solver ?

Again, you may suggest the good website or paper for reference.

Thank.
Roger

Title: Re: What is full-wave EM solver?
Post by Frank Wiedmann on Oct 13^th, 2004, 8:41am

A 3D solver can solve problems of arbitrary geometry. A 2.5D or planar solver can typically solve problems where you have arbitrary shapes in a number of metal layers which are separated by layers of dielectric and may be connected by vertical vias. To get a better idea, you might want to download the free planar solver from http://www.sonnetusa.com and take a look at the problems it can solve.

Title: Re: What is full-wave EM solver?
Post by matthew bibee on Nov 2^nd, 2004, 12:07pm

Hi

The difference is how the two tools solve problems. A quasi-static solver assumes that all fields are TEM. It decomposes maxwells equations and solves electric and magnetic fields independently of one another. For example I think the ansoft Q3D quasi-static tool will solve the E field first and spit out a capactiance matrix for your problem. It then goes on to solve for magnetic fields and will give you an inductance matrix for the conductors in your problem.

A limitation/requirement of quasi-static tools is that physical size of your problem must be smaller then 1/10th the wavelength of your highest frequency of interest. Usually this isn't a problem for most chip interconnects.

A fullwave solver makes no assumption about field relationships and will find all modes that can propagate through your problem structure. It also can handle problems that are physically large compared to the wavelength of your highest frequency. The output of these tools is some type of network parameter. Usually S-parameters. They're also trickier to setup and take longer to solve.

If for example you were doing work Gbs serdes this type of tool is appropriate for things like IC packages, PCB vias. Structures that are electrically large.

A fullwave tool will also be able to calculate losses due radiation.

Hope this helps
Matthew

Title: Re: What is full-wave EM solver?
Post by Colin Warwick on May 20^th, 2011, 6:29am

Static means simplifying Maxwell's equations such that there is no coupling at all between E and B fields:

ε div(E)= ρ
curl(B)=µ J

With quasi-static, one form of coupling between B and E is considered: the E field generates conventional current in conductive materials (Ohms Law) and then this conventional current adds to the external J stimulus and generates B in the normal (Biot-Savart) way.

curl(B)=µ(Jexternal+σE)

In both static and quasi-static, the time derivative terms in Maxwell's equations are set to zero. In other words, the displacement current term that Maxwell added to Ampere's Law is set back to zero and Faraday's Law becomes:

curl(E) = -dB/dt = 0

In contrast, full wave solvers consider all the time derivative coupling terms in Maxwell's equations to be finite.

Best regards,

-- Colin Warwick
High Speed Digital Blog

Title: Re: What is full-wave EM solver?
Post by markspend on Jul 4^th, 2013, 10:05am

Hey Guys well i think that HFSS is a complete wave solver and gives resutls that are more precise than Ansoft aerial developer. Moreover ansoft is suitable for planar style and HFSS can be used for a myraid of aerial styles.Thanks!!