ESP32 Forum

I'm trying to tune an antenna as seen above, using this wonderful Smith Chart Tool. It needs to match 35 + 10j characteristic impedance.

I have found a tool like the Microstrip Impedance Calculator to determine the impedance of the transmission lines.

However, i am unsure how to determine the characteristic impedance of the stubs that don't have a ground plane (green area) behind them. Does anyone know how that impedance is calculated?

Hey brento,

Not able to see the image you uploaded

It should work now. Thanks for the notification!

I have heard on another forum, that my notion of what a 'stub' was, was incorrect. The antenna, is not a stub, but a stub is something above a ground plane.

With that in mind, does that mean that when I use the Smith Chart Tool, that I can consider the illustrated antenna to have zero impedance in the modelling?

Look here: https://www.ti.com/lit/an/swra638/swra6 ... 1318797718

But, this going to be an approximation at best. Once you get close, you are going to need to make a board and actually measure it’s performance.