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Create a CPW Port with FEKO

Hi friends,

I currently working on a project to create a planar UWB Antenna. At this point I having trouble to create a CPW Port for my microstrip. I searched the internet for solutions, but didn't got what I was looking for neither understand the answers. I'm running FEKO 7.0.1-256428.

I would be pleased if someone can help me. This is my thisis.

I've attached a CADFeko File to show my issue.

Thanks for some help.

Greetings Mathias

microstrip_koppl_a3mm_01_cfx.7z

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Altair Forum User

Hi Mathias,

Maybe you can clarify the problem for me a little. What I see in your model is 100% correct, you're just missing a source. You've basically created a port (which is a point where a source can be attached) but never put energy into the system. I got the model running by:

Right-clicking on 'Port1' on the Construct tab on the tree in the left of CADFEKO
Adding a 'Voltage source' with 1V;0deg amplitude

The oldest version of FEKO I have is 7.0.2. You can try to open the model but it might be too new for your version.

My questions:

Is this what you were looking for? i.e. Were you just trying to get it to run?
Were you specifically trying to create a different type of port? What were you hoping to achieve or investigate?

Regards,

Andries

PS: I would recommend that you look at Examples Guide A-8.4 'Edge-fed, planar multilayer substrate' which goes through similar creation steps. Browse through some of the other examples as well and see if there's something that looks useful to your problem.

PPS: That model definitely requires that you take very careful notice of the currents flowing on the feed line as well as the smaller elements of the fractal. My guess is you'll need a much finer mesh before you get accurate results!

microstrip_koppl_a3mm_01.modified_v702_cfx.7z

Altair Forum User

Hi Andries,

Thanks for your quick answer. I was able to open the file.

My aim is to measure S11. I created a Source, but it seems that it didn't was saved in the file.

You did excatcly what I was doing, so I think I was on the right way . I just was in feared, that I used the wrong Port-type to greate my CPW-Port.

Another question:

If I want to create a substrate underneath a perfect electric conductor I've got an error, that triangles have the wrong material. I only solve this issue by applying a gap of 1µm between both materials. I'm not sure if this is as it should or if it create wrong measurement-results.

thanks for your help.

Regards, Mathias

Altair Forum User

From the model that you originally gave me, it looks like you already have substrates defined by using the infinite ground plane techniques. If you want to add more layers then you can do so on the 'Plane / ground' dialogue. If you want to physically model finite-sized ground planes, then you would need to explicitly model the geometry without the substrate tool (see e.g. have a look at Examples Guide A-10).

If I want to create a substrate underneath a perfect electric conductor

By definition, this is not possible. You defined an infinitely large plane of PEC which will prevent any energy from propagating underneath the ground plane. Again, look at Example A-10 if you want to see how to 'cut through' such a PEC plane.

Regards,

Andries

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thank you very much. The Example A-10.1 was a good hint.

Unfortunately, I'm stucking now on a nother point. I've created my antenna similar to a patch antenna, like it is shown in example A-10. Now I wanted to start measure the S11 parameters. But if I start the solver I'm getting the error: ERROR 33270: A triangle edge is too short or EPSENT is too large

Can you please help me to get rif of this error.

Thank you very much!

fractal_capacity.7z

Altair Forum User

I responded to your last query regarding ERROR 33270 in the related question: