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Click here to see PolyStrata coax analyzed with an Henrik Forstén's on-line EM tool
Click here to see PolyStrata 10dB coupler design using Henrik Forstén's on-line EM tool
Click here to see a GaAs microstrip10dB coupler analysed with Henrik Forstén's tool
New for March 2026. An awesome EM tool appears on the Henrik Forstén's website, among a lot of other cool blog posts. Thanks to Alex for pointing this out.
Here is his bio from the site:
My name is Henrik Forstén and I'm a Finnish electrical engineer working as a researcher at VTT. Lately I have focused on mm-wave MIMO radars. I do MMIC design, antenna design, analog and digital PCB design, FPGA programming and PC programming.
His 2D solver can be found here, you should bookmark it:
https://hforsten.com/field_solver.html
This is a great news for those of us without access to expensive EM tools. You can solve microstrip, stripline and GCPW geometries in single and differential modes. Options include solder mask, side walls, ground cutouts and more. Using sidewalls, you can even analyze rectangular coax, a.k.a. PolyStrata coax!
2D solvers only work on straight, uniform transmission lines, if you want to analyze bends and other details you will have to find another way to do this. But the 2D solver is a big step up from spreadsheet and linear models (looking at you, Microwave Office), and it is very fast. Did we mention it is free to use!
Below, we provide a microstrip example.
This is the "Geometry" tab where you set up the all dimensions and material properties except the length of the line (we don't expect you to be able to read the data on this image. One of the fearure of the tool is that you can store your work, including geometry, material properties and analysis frequencies. The data for this example iis stored here so you can go there and run it yourself. When you hit "solve" it draws in the field lines. We like to beat the crap out of tools when we unbox them so we specified 10,000 points. The solution only took about a minute!
The "Results" tab plots the characteristic impedance. We tested it by solving down to 1 MHz. The solver does a nice job of showing low frequency dispersion.
You can change the X axis to log frequency. This gives a much prettier image of the dispersion.
The "S-parameter" tab plots S11 and S21 magnitudes. The default length is 1mm, but in this window you can change the length..
Here is 100mm line.
By tweaking the metal and dielectric properties you will be able to predict transmission line attenuation. If you really want to predict attenuation accurately you need to fabricate and test sample transmission lines to backfit metal conductivity and dielectric loss tangent, particularly if you plate the transmission lines. Don;t be surprised when you observe more loss than you predicted. 100mm is probably a good length for extracting these parameters.
From the S-parameter tab you can download an S2P file.
This is beautiful on-line tool, thanks to Henrik! Now you can move on and admire some more examples
Click here to see PolyStrata coax analyzed with an Henrik Forstén's on-line EM tool
Click here to see PolyStrata 10dB coupler design using Henrik Forstén's on-line EM tool
Click here to see a GaAs microstrip10dB coupler analysed with Henrik Forstén's tool