what is the relationship between the trace width of PCB antenna and FR4 PCB thickness for a antenna lambda / 4.
The white paper on lambda/4 printed monopoles explains the trace widths you want to have for a standard FR4 substrate, and should be helpful for designing your antenna.
The thickness of various traces in relation to FR4 characteristics can be found by using a calculator like this, or by applying the formulas provided there.
Thanks for your answer.
I know the relationship with ground plane bellow but the antenna part don't have ground plane. So i d'ont know the relationship of trace with when there don't have ground plane below.
From the white paper:
"The width of the monopole trace is W = 1.5mm"
For FR4 thickness equal to 1.6mm.
but for 1mm FR4 thickness?
1.5mm is a chosen value that works well for the intended frequencies, it also works well for common PCB materials. The bandwidth of the antenna scales with the trace width, so if you make the trace width small the bandwidth becomes small. For an engineering approach chose 1.5mm.
If you want to dig deeper into the topic, consult a book on antennas for printed applications. You could also simulate the design with an electromagnetic simulator (if you are a student you can get the student edition of CST for free).