Placement of nRF module inside enclosure with surrounding metal components

[Kenan]

Hello dear support team,

We are in the process of designing an enclosure for our device. The enclosure is going to be molded and we would highly appreciate your support to figure if there are any major concerns with the placement of some metal parts around the BLE antenna leading to any significant deterioration of radiation performance. We require connection from distances around 10m away from the device.

We are using ublox's BMD-350 module which has your nRF52832. The module uses a ceramic chip antenna.

The module is surrounded by the following metal parts:
- Three stainless steel screws
- An SD card holder that's mainly made of stainless steel
- 2 AAA batteries with their holders. The holders are made of STEEL 65Mn.

The following are some images of placement of these components with regards to the chip antenna (chip antenna is on the back side of the board and represented with a blue rectangle):

Top view:

Side view:

The BMD-350 datasheet recommends the following copper keep-out which we do follow in out design:

As for the enclosure itself, it's made out of plastic. There's no worries on that side. 

Thanks,
Kenan

[ketiljo]

Without knowing what antenna that's used on the module. I'd say that you should keep metal parts > 5mm from the antenna. Since it's a module, you can't compensate for detuning of the antenna by nearby metal so it's more important to keep the distance here.