PCB Antenna Tuning

[Brento]

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?

[MCUism]

Hey brento,

Not able to see the image you uploaded

[Brento]

It should work now. Thanks for the notification!

[Brento]

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?

[Beowulff]

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.