How I can freely modify the substrate in ADS?

I really need to modify the dimensions of the substrate, but can not do it. I find articles on the Internet to design substrates with three dimensions. For example: "Substrate Dimensions: 26x45x1 mm". But when I click EM Simulation Setup, and then in substrate, I create a new substrate. For example, the default is Alumina, then click on the layer, and then I have just the "Thickness" option. How can I set a substrate in three dimensions as well?

You'll need to use FEM. Look in this section of the ADS manual: qthelp://ads.2015.01/doc/em/Defining_Substrates.html under "Editing Properties for the Entire Substrate"

Can you replace this link ? I can't acess it. And I did not find the manual. So can you send the correct link please ? Thank you so much

The same documentation is also available in the Keysight EEsof Knowledge Center:
http://edadocs.software.keysight.com/display/ads201501/Defining+Substrates
Supported customers or university students can access the Knowledge Center.

From the ADS main menu, select Help > Topics and Index. Then enter this string into the Address field: qthelp://ads.2015.01/doc/em/Defining_Substrates.html and hit Enter. This assumes that your ADS installation includes the documentation.

> I really need to modify the dimensions of the substrate, but can not do it.

Momentum uses a method that simulates with *infinite* substrate size - stacked dielectric layers that are very very very large.
This allows to use a simulation method that is very efficient and accurate. For most simulation cases, it makes no difference if you include a finite dielectric size or not. Only few cases, like wires or antenna elements very neat to the substrate edge, will show a difference in results when you simulate the actual substrate size.

FEM *can* simulate finite dielectric size, *but* in general it is less efficient and it requires more simulation effort and well trained users to get the same accuracy level. From 15 years of experience as an EM expert: users make more mistakes with FEM simulation, leading to results that are not very accurate. Yes, FEM is very useful in those cases where finite substrate size *does* matter - but in many cases infinite substrate size results will be almost identical and then I would always prefer Momentum instead of FEM.

>I find articles on the Internet to design substrates with three dimensions. For example: "Substrate Dimensions: 26x45x1 mm".

Sure, that is what they built. But it does not mean that the exact PCB (26mm x 45mm) size makes a difference in results.

Volker, can you help me to find this "FEM" ? It is very important to me able to define the dimensions of the substrate as it is for a build project. I send a print of my ADS layout, I don't have "Momentum" in my layout, why ? Please, help me :(

附图/附件

FEM..JPG

> Volker, can you help me to find this "FEM" ? I send a print of my ADS layout, I don't have "Momentum" in my layout, why ? Please, help me :(

"Momentum" and "FEM" are the two possible EM solvers, see screenshot. Both require a license - check what EM options are included in your license file.

> It is very important to me able to define the dimensions of the substrate as it is for a build project.

If you are an experienced EM user, I would take your word for it. If you are a new user, you might misunderstand the importance of substrate size. For your patch antenna (?) it is usually not important.

附图/附件

fem_Mom.PNG

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