Antenna selection for FR4 layout

[Usman Rahim]

Hi, we are working on custom board using nRF52811 SOC, I have some confusion

1. regarding the antenna design, I copied the Antenna from Dev board, but it is designed for 1.6mm FR4 board, while i am planing for 0.6mm or 0.8mm, so will the calculation of length of antenna vary for me?

2. in the document nwp_008.pdf , it says  guided wavelength  on the FR4 substrate is about 0.75 , How it is calculated. and will it change for me  if i change PCB to 0.8mm or 0.6mm. Thank you

3. my current layout is shown in picture attached.

[ketiljo]

As the antenna runs along the top of the PCB, the reduction factor is somewhere between free air and RF4. But the actual length of the antenna can change a bit depending on the size of your ground plane. So the best is to make the antenna ~25 mm long and trim it to max range after you get the PCBs back. If you have access to a VNA, you can use this to measure the resonant frequency of the antenna and trim it to 2.44 GHz.