Question about chip antenna placement on a PCB

RE: Question about chip antenna placement on a PCB

Bendik Heiskel — Thu, 09 Apr 2026 12:29:38 GMT

The line width for a 50 Ohm transmission line is dependent on the thickness and dielectric properties of the PCB substrate, both of these parameters you can get from your PCB manufacturer. The width can be calculated using tools like AppCAD or Saturn PCB Toolkit, note that this type of transmission line is called a grounded coplanar waveguide. Some PCB manufacturer can also calculate the width of the trace for you to suite the substrate being used.

The matching network C315, L303 and C316 isn't needed, The SMA connector and the external antenna both have a impedance of 50Ohm already, so as long as the transmission line from the connector to the end of the radio matching network(in this case L302) also have an impedance of 50 Ohm there is no need for the matching circuit.

Other than this the layout looks good.

Best regards,

Bendik

RE: Question about chip antenna placement on a PCB

paul0208 — Thu, 09 Apr 2026 07:35:30 GMT

This is for central, nRF52833.
I wonder it looks good for matching also.

Line width is 0.762mm, two layers, as your ref design.

BR
Paul

RE: Question about chip antenna placement on a PCB

Bendik Heiskel — Wed, 08 Apr 2026 08:05:15 GMT

This battery placement should be OK, since it is not within the antenna keep out area.

RE: Question about chip antenna placement on a PCB

paul0208 — Wed, 01 Apr 2026 14:22:06 GMT

This is bottom side.

RE: Question about chip antenna placement on a PCB

Bendik Heiskel — Wed, 01 Apr 2026 08:36:48 GMT

Hi Paul,

The layout of the antenna looks OK

[quote user=""]For additional RF tuning between L2 and the chip antenna, is an additional pi-network required?[/quote]

L1, L2 C3 and C4 are the radio matching and filtering circuit, it can not be used for antenna impedance matching.

From the snippet from the antenna datasheet you can see that a Pi network consisting of 2 shunt capacitors and one inductor is recommended:

As a starting point the capacitors can be NC/DNP while the inductor can be replaced by a 0 Ohm link. The values of these components must be determined after the board is produced and the impedance of the antenna is measured using a VNA.

[quote user=""]A CR2032 battery will be mounted on the back side.[/quote]

Where is the battery placed in relation to the antenna? Is it directly behind it?

Best regards,

Bendik