PCB board underneath the ESP32-S3-WROOM-2 module antenna area

[Baldhead]

Hi,

I would like to know if i can leave the base board under the ESP32-S3-WROOM-2 module antenna area.
I will leave only the FR4 with the solder mask, without the copper or components, obviously.

Will this influence the antenna a lot ?
Am i required(obligated) to cut FR4 off in this area ?

I also have a box printed on a 3D printer in PLA, underneath this antenna area, with 5.4 mm thick.
Does the pla plastic box also influence the performance of the antenna ?

Two images attached.
One picture is the partial pcb and the other picture is the pla box where the red area will be the wifi module antenna.

Base Board Specs:
FR4
Thickness = 1,6 mm

Espressif site, PCB Layout Design:

If there is a base board under the antenna area, it is recommended to cut it off to minimize its impact on the antenna.

Link:
https://docs.espressif.com/projects/esp ... esign.html

Figure:
https://docs.espressif.com/projects/esp ... -clearance

Thank's.

[ESP_Sprite]

You can; it might impact antenna performance somewhat but I've seen it done pretty often so I can't imagine it'll be by much. Same for PLA. The most important bit is to not have any metal things in the neighbourhood of an antenna.