to go to our main CAD page
We currently have two other pages
on EM analysis:
Sonnet for EM analysis (Sonnet Software)
Note to EM software
suppliers... we could use your help, and you could use ours! Talk
to us! Special thanks to Jim from Sonnet, who fixed up our definitions
of 2.5D and 3D during October 2009!
Second note to EM
software suppliers... if you want your products featured here, try
sending us a check and see if this helps.
The original "inventor"
of electromagnetic simulation was James
Clerk Maxwell. Over one hundred years ago,
Maxwell's equations provided the solution to every EM problem
that man has encountered. Too bad he didn't have a computer to help
him with all the calculus that is required to solve even the simplest
EM problems. By the way, it was Oliver
Heaviside that reduced Maxwell's many equations to four!
When you purchase or use EM software,
there is a convention that tells you how many of the three primary
dimensions (X, Y and Z) are considered in the analysis.
2D implies transverse
EM waves are analyzed (X and Y directions only), most typically
for microstrip transmission lines. No RF currents are permitted
in the Z-axis (into or out of the substrate.)
2.5D implies that RF currents
are allowed in two directions only (X and Y), and fields are calculated
in all three dimensions (X Y and Z). No vertical currents are allowed.
Examples would include microstrip or stripline filters which do
not contain vias to ground. Note: This term has also been used to
refer to 3D planar solvers such as Sonnet (Sonnet Software product)
and Momentum (Agilent product) even though they all allow vertical
3D Planar implies that
currents and fields are allowed in all 3 directions, but circuits
are restricted to stratified dielectric media. Examples would include
most MMIC, RFIC, and PCB circuits. Examples include Sonnet (Sonnet
Software product) and Momentum (Agilent product).
3D Arbitrary or 3D
Full implies electromagnetic interactions in all directions
are incorporated in the simulation. If you are an antenna designer,
you can skip all the cheap stuff and go right to 3D analysis. Here's
an entire Microwaves101 page devoted to this
Another differentiator between
3D Planar and 3D Arbitrary is how ports are handled. For 3D planar,
port values are read directly from conductor currents. For 3D Arbitrary,
port values are usually inferred from the fields at port locations.
This can make a difference in the accuracy, and even the definition
of the resulting S-parameters.