I would like to know how to compute the impedance at the edge of a microstrip patch in CST. Apparently it has been done in one of the papers I was going through and I shall like to know how:
"The impedance seen at one edge of the patch is found to be 320-55j from the simulation by CST Microwave Studio"
There are two methods to calculate impedance, one by doing manually and other using CST or any commercial software.
Select the edge, then go to parametric analysis setting and run it for impedance. Using S parameter, impedance can also be measured as there is relation between Z and S parameters.
Could you give some more detail about what do you exactly want to find out.
Thanks,
There are two methods to calculate impedance, one by doing manually and other using CST or any commercial software.
Select the edge, then go to parametric analysis setting and run it for impedance. Using S parameter, impedance can also be measured as there is relation between Z and S parameters.
Could you give some more detail about what do you exactly want to find out.
Thanks,
Do you mean input impedance?
If it is that, then simulators like CST, HFSS, IE3D can give you Z(1,1).......
Everywhere you put a port, you can see the s-parameters and then change it to the Z and Y by using the "Template Base Results" from Post-Processing ribbon.
Ms Dwivedi:
I have selected the edge of the patch but could you please elaborate a bit about where to get the 'parametric analysis setting' in order to proceed.
Thank you so much for your reply. I am trying to find out the input impedance of the patch as in the figure shown below, given that I am feeding it with a 50 Ohm MSL. As in quite a few other cases, we observed the necessity of inset feeding for a proper match as the impedance at the edge of the patch is generally quite high. Estimating this impedance first is therefore my first target here. Note that the input port is at the edge of the substrate of course, where the MSL begins.
I am trying to proceed in the way you mentioned. We do have formulae in Balanis for example stating how to find this out theoretically but I wanted to check how we could do so using CST directly.
In the figure below, a microstrip line feeds the patch and the impedance at the edge of the patch has been calculated. The procedure, though, of how to calculate the same has not been mentioned. That's what I would like to clarify.
Anvesh, Meysam : The port is at the edge of the substrate where the Microstrip Line starts while I'd like to know the impedance at the edge of the patch.
In general, the input impedance of 200 ohms starts and goes to 0 ohms (short circuit) at the center of the patch at a given frequency.
Thus, vary the depth of a micro-line to find the 50 ohms which should be between 1/6 of the total length of the patch.
Thank you for the ideas regarding a theoretical idea and a rule of thumb approach of determining the same. This definitely is one of the alternative ways which is good to know but the original query about finding this directly from the software is unfortunately still not clear for me.
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