Routing near WROVER PCB trace antenna

[zliudr]

I've always placed the WROVER module so that its PCB trace antenna overhangs from the edge of the board so it's clear from anything it needs to keep out (according to the pinout of the module). I just wonder, this time I need to place the module around the center of the board.

Should I create an exclusion zone so that my ground planes are NOT directly underneath the trace antenna area?

My understanding is that having a solid plane reflects the emitted EM wave. But at 2.4GHz, the wavelength is around 12.5cm. The distance between the antenna and the top ground plane is about 1.2mm, so it's 1% of the wavelength. I think the interference from reflected wave is minimal but emitted wave is partially shielded if the ground plane is underneath so the router will have some issues with receiving from the board, dependent upon their relative orientation. Also, when receiving, the ground planes underneath will partially shield the wave so the board's reception will be more dependent on its relative orientation with the router's antenna, so I need to remove ground planes under the trace antenna, not due to interference from reflection but due to partial shielding, correct? Thanks.

[becorey]

First, really consider if you can't get the wrover to the edge of the board. That is the best recommended placement for antenna reception.

If you must place in the center:
Keep 15mm clearance to the left, top, and side of the pcb antenna. No copper, routing, or components in this keepout area.



Fig 13 from the esp32 hardware design guide
https://www.google.com/url?sa=t&source= ... 9397876620

[zliudr]

Thank you so much! I didn't catch that so hopefully I still have strong enough signal. I did a test, very crude but inconclusive:
Attach another board with both top and bottom layer ground plane right under the antenna, short grounds of both my prototype board and the second board. Did some RSSI tests, didn't see much difference with the second board right under the antenna and with it removed.

Anyway, I'll get the board soon so I'll post my results and will always have the recommended placement and clearance in mind!