input impedance of antenna

hello, everyone!

I'm designing a rfid garment passive tag antenna. My problem in this project is how to find input empedance at arbitrary points in the antenna to insert lumped port there.
Does anyone know how to find it and may be the name of software which can help me for this? Please let me know.
Thankyou!

With which software are you 'designing' your tag antenna ?

As far as I know, all EM software should support S-parameter (if not the input impedance itself directly) calculations.It would then be trivial to convert from S-parameter data to input impedance.

by designing i will assume that you means in some professional software, that ought to have S parameter analysis, so plotting S11 vs Frequency of operation of antenna will give you impedance at different frequencies that you can then match with a matching network!

What do you mean with "arbitrary points in the antenna"?

Have nice day every one!

I am finding the way to simulate textile antenna. I don't know how to perform the different between using normal material designing antenna and using textile if I simulate my antenna in a normal way.

Does anyone has a tool to help me in this problems.



the arbitrary points I mean the point in the patch antenna in any coordinates that I want to know exactly the input impedance. And I have to find a tool to display it when I point to antenna.
Thanks!

A textile antenna should not be different from a "normal" antenna.
You can characterize your material (electric conductivity or er of the substrate) and then use this in the simulation.

I think it is not possible to get the input impedance at arbitrary points, since this means that you would feed the antenna at this point which leads to another current distribution on the antenna and thus to different behaviour of the structure. You would have to move the feeding position around and conduct a simulation for each feeding position. Probably you would do this automated with a parameter sweep or a simple script.