Hi.
I am trying to implement the reference layout for nrf54l15: https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/chapters/ref_circuitry.html
Just a quick question. Is there supposed to be a grounding under then antenna for the bottom layer?
It looks like it from the drawings.
Hi, Pål.
No, in most cases there shouldn't be ground copper on the bottom layer beneath the antenna. This depends on the antenna, and there are some antennas that are designed to have ground copper beneath them, but for most antennas there should be a cut-out area around the antenna in all layers. The antenna's datasheet will provide guidelines for this.
What I suppose you see in the drawings, is the cut-out beneath the coplanar waveguide in the inner layers and the ground copper beneath it on the bottom layer.
If you want to see an example of a layout that includes an antenna, have a look at the nRF54L15 DK. Its hardware files are downloadable from here.
Best regards,
Mathias
hello.
Thanks for the answer..
But im asking for this exact design (https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/chapters/ref_circuitry.html).
And bottom layer:
Am i misreading the bottom layer here? Or is this one of the designs where it is designed to have it is designed for a grounded bottom layer? Or am i supposed to extend the antenna here and keep all grounding away from it?
The reference layout you're referring to doesn't include any antenna. It only has a coplanar waveguide that stops when it reaches the point where it would be possible to add an antenna.
Please have a look at the DK's layout to see what this reference layout looks like in combination with an antenna (and a connector in this case).
Boggibill said:No wonder there coverage is bad when there's no antenna attached to it :)
An antenna is nice to have! 
Boggibill said:Do you have any examples for an antenna without the connector? Or can i just remove the connector and connect that specific antenna to the reference layout?
Yes, you can just remove the connector. If you're not able to connect the antenna directly at the end of the radio's matching network, remember to use a 50-ohm coplanar waveguide for the connection between the radio's matching network and the antenna's matching network.
On the DK, there is no antenna-matching network, but I'd recommend adding a shunt component for matching of the antenna if you're planning to use a PCB trace antenna. If you find out you want to use a chip antenna, you should use the matching network found in the antenna's datasheet. This will in most cases be a Pi-network.
We do have a white paper for designing a quarter-wave monopole antenna, that you might find helpful.
Boggibill said:No wonder there coverage is bad when there's no antenna attached to it :)
An antenna is nice to have!
Boggibill said:Do you have any examples for an antenna without the connector? Or can i just remove the connector and connect that specific antenna to the reference layout?
Yes, you can just remove the connector. If you're not able to connect the antenna directly at the end of the radio's matching network, remember to use a 50-ohm coplanar waveguide for the connection between the radio's matching network and the antenna's matching network.
On the DK, there is no antenna-matching network, but I'd recommend adding a shunt component for matching of the antenna if you're planning to use a PCB trace antenna. If you find out you want to use a chip antenna, you should use the matching network found in the antenna's datasheet. This will in most cases be a Pi-network.
We do have a white paper for designing a quarter-wave monopole antenna, that you might find helpful.
