I have been experimenting with a free planar 3D E&M simulation tool called Sonnet.
https://www.sonnetsoftware.com/products/sonnet-suites/
The price of their lite version is just right at a price of free.
I have used the tool for a few hours and found the tool quite easy and intuitive to use.
Instead of following the suggested geometry in an application note for an inverted-F antenna or meandered inverted-F antenna, design it yourself!
Based on my limited understanding of the tool, it simulate in a metal box. So you need to make the geometry of the box large enough such that the metal side walls don't influence the circuit your trying to simulate.
So I made a big box and drew a basic inverted-F antenna adjacent to a large copper plane.
I set the stack up to have the antenna on an FR4 substrate with lots of air space above and below the antenna under test.
My box looks somewhat comical, perhaps in the future I should find some rules of thumb for dimensioning.
I placed a differential measurement port (the box labeled: 1) right at the antenna's feedpoint
Setup an s-parameter simulation from 2GHz to 3GHz
This antenna as a low return loss from 2.4GHz to 2.5GHz
With some parametric analysis of the antenna's geometry we may be able able to improve the return loss in the 2.4GHz band. You could export the s-paramaters of the antenna to design a matching/filtering network for an even better match to 50 ohms.
I am really only scratching the surface here. I am quite impressed to say the least.
There are a few demo projects included with the tool
Pretty neat, glad I downloaded it.
