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Thin Film Transmission Line - RF

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I am trying to model the scattering parameters for CPW and Microstrip transmission at microwave frequencies using the RF package. The issue I am running into is my lines are very thin in comparison to their other dimensions. The lines I want to model are about 200nm thick while the widths are on the range of 400um. While I would be fine with modeling these as just 2-D sheets because the extremely small thicknesses would have little contribution to the fields, the resistance is not small. Due to the small thicknesses the resistances are decently high that the perfect conductor approximation is not true even in the microwave region.

I tried brute forcing the problem by just placing blocks with the appropriate dimensions but I run into meshing problems. The large contrast between the thickness of the line and the width/length is making it difficult to construct a mesh.

I tried making the line a 2-D plane but then I am forced to model it as a perfect conductor as far as I know, giving the sheet a conductivity effectively makes it an insulator I believe. Unless there is a way to use a 2-D plane model for the transmission line and take into account the resistance?

Is there some thin film technique I can apply using the RF package to ignore the thickness of the transmission line but still take into account its resistance? Or is there a good technique for meshing geometries with such extreme contrasts in dimensions?

3 Replies Last Post Feb 6, 2015, 11:41 a.m. EST
Edgar J. Kaiser Certified Consultant

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Posted: 10 years ago Feb 6, 2015, 4:41 a.m. EST

The impedance BC is exactly what you need.

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
The impedance BC is exactly what you need. -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

Sergei Yushanov Certified Consultant

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Posted: 10 years ago Feb 6, 2015, 8:18 a.m. EST
Robert,

Use Transition Boundary Condition to account for metal losses of microstrip line with specified thickness and conductivity. This BC is used on interior boundaries.

Impedance boundary condition is used on exterior boundaries representing the surface of lossy domain.

Regards,
Sergei
Robert, Use Transition Boundary Condition to account for metal losses of microstrip line with specified thickness and conductivity. This BC is used on interior boundaries. Impedance boundary condition is used on exterior boundaries representing the surface of lossy domain. Regards, Sergei

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Posted: 10 years ago Feb 6, 2015, 11:41 a.m. EST
These are the tools I was looking for. Thank you both.
These are the tools I was looking for. Thank you both.

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