Help in ADS regarding how to change material properties of ground plane?

Hi Everyone,
I'm currently designing a photoconductive micro strip antenna, whose ground plane doesn't use conventional metal(copper), instead I'm using a lower conductivity material. Now when I try to optimise the printed patch, it asks me to give a certain value for conductivity (MSUB), which is for the radiating patches and strip lines. But couldn't find any option to input the value for the second conductive material which is the ground plane. And change the properties of ground plane does change the impedance matching of the antenna, which I verified in CST.
Hence if any ADS expert could suggest me how to change the conductivity of ground plane (not the stripline) that would be really helpful

Many Thanks!

I'm confused. MSUB is used for circuit simulation and not for EM.

For Momentum EM, materials are defined in the Momentum substrate definition. You have not mentioned which ADS version you use, so I assume it is ADS 2011 or newer. Define the conductor material for your bottom ground plane in the substrate editor: Technology > Material Definitions. Then, select the infinite bottom ground plane in your substrate and assign this material that you have defined.

First of all I would like to thank volker@muehlhaus for your reply.

Now, I'm currently using ADS 2013, and have designed a powerdivider circuit along wiith patches in Schematic section using T-Lines microstrip. My circuit is perfectly matched. Now what I wanted to know is how do I use this printed patch on a substrate along with low conductive ground plane on ADS? And I also wanted to optimise the printed patch on the substrate of the microstrip antenna by taking into consideration the low conductivity of the ground plane material, because the printed patch that shows S11 < -50dB in schematics gives a mismatched circuit when I want to simulate the same design in CST.

And also I agree with you that MSUB is used for circuit simulation, but since it asks for dielectric of the material as well as TanD of the metal stripline and patches, I thought it might as well take the ground plane into consideration. Hence if I want to consider the ground plane with different conductivity I need to create the material as you said (Technology > Material Definitions. Then, select the infinite bottom ground plane in your substrate and assign this material that you have defined), but on which platform? Will I be still using schematic or should I use generate layout? And also in the schematic section can I do EM simulation, if not how do I use this impedance matched printed circuit on a substrate and a low conductive ground plane?

If you have a preferred solution for this please let me know. I shall be really grateful if you could help me with this.

Many Thanks

First of all I would like to thank volker@muehlhaus for your reply.

Now, I'm currently using ADS 2013, and have designed a powerdivider circuit along wiith patches in Schematic section using T-Lines microstrip. My circuit is perfectly matched. Now what I wanted to know is how do I use this printed patch on a substrate along with low conductive ground plane on ADS? And I also wanted to optimise the printed patch on the substrate of the microstrip antenna by taking into consideration the low conductivity of the ground plane material, because the printed patch that shows S11 < -50dB in schematics gives a mismatched circuit when I want to simulate the same design in CST.

And also I agree with you that MSUB is used for circuit simulation, but since it asks for dielectric of the material as well as TanD of the metal stripline and patches, I thought it might as well take the ground plane into consideration. Hence if I want to consider the ground plane with different conductivity I need to create the material as you said (Technology > Material Definitions. Then, select the infinite bottom ground plane in your substrate and assign this material that you have defined), but on which platform? Will I be still using schematic or should I use generate layout? And also in the schematic section can I do EM simulation, if not how do I use this impedance matched printed circuit on a substrate and a low conductive ground plane?

If you have a preferred solution for this please let me know. I shall be really grateful if you could help me with this.

Many Thanks

I'm even more confused now. What I described requires Momentum (or Momentum co-simulation). You mentioned an antenna, which has no circuit model and can't be simulated with circuit models. So obviously you are already using EM simulation with Momentum for the antenna part, or possibly for all layout? Then, where exactly did you get lost?

Hi volker@muehlhaus,

If what I've written confuses you, I'll lay it out straight. I've created a low conductive material in the (Technology > Material Definitions) section and named it conductor_1. How do I use conductor_1 in T-line microstrip of the schematic diagram? The diagram is a matched-printed microstrip line, should I go to (Layout> Generate layout) of the schematic and assign the material for ground somewhere? And what is Momentum co-simulation? How do you generate it? Is it a special feature in ADS. I apologize for my ignorance, since I'm new with ADS.

No. The materials defined in the technology are used for the EM substrate definitions.

You mentioned an antenna, and for that, schematic level simulation is not applicable anyway. The correct method is to analyze the antenna with EM (Momentum), and then use the EM results in schematic simulation.

The input for EM simulation is a layout that you can draw from polygons (arbitrary layout) or from pre-defined layout elements.
The output from EM simulation is S-parameters, which you can use in different ways: S1P data block or emModel.

Schematic simulation is good for cascading pieces of non-radiating transmission lines, where ADS has electrical models for each of these pieces. Schematic simulation is not approriate for radiating structures -> antennas. For antennas, you need EM simulation.

You can mix model based schematic simulation (for the feed network) and EM results (for the antenna) in your schematic. For the EM part, you then need to have a layout and an EM substrate defintion. In that EM substrate definition, you can define the bottom conductor as you wish. That's what I mentioned in post #2.

Here's an ADS tutorial:
http://www.rf-design-tips.com/ads-qu...line-training/
EM is covered in the "Day 3" video
http://www.rf-design-tips.com/ads-qu...line-training/

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