Monopole Antenna & matching network of nRF52 DK with nRF52820 Reference Design

RE: Monopole Antenna & matching network of nRF52 DK with nRF52820 Reference Design

mathiaso — Tue, 01 Oct 2024 11:41:35 GMT

No worries, Muhammad.

16 mm might sound a bit short, thinking of the numbers found in the white paper I linked to earlier and the antenna on the DK. It is possible to add length to the antenna during the tuning process using copper tape, although this is not as easy and accurate as cutting the length of the antenna.

Good luck with the testing!

RE: Monopole Antenna & matching network of nRF52 DK with nRF52820 Reference Design

X4ce — Tue, 01 Oct 2024 03:00:46 GMT

Thanks!

I have used nRF52820's matching network with the monopole antenna with length around 16mm & width 1.27mm. I have ordered PCBs and will test the radio, accordingly!

RE: Monopole Antenna & matching network of nRF52 DK with nRF52820 Reference Design

mathiaso — Mon, 09 Sep 2024 07:36:09 GMT

Hi, Shahid.

The matching network found in the nRF52820's reference schematic (reference matching network on nRF52820-QDAA shown below) is there to optimize the output power and suppress the harmonics from the radio.

Thus, this is sort of independent from the antenna's matching network which is there to tune the antenna closer to the 50 ohms of the coplanar waveguide it is connected to.

When looking at the nRF52 DK, with hardware files found here, the matching network circled with orange is the matching network of the nRF52832's radio, equivalent to the nRF52820's matching network shown above. The single shunt component circled with violet, is the matching network of the antenna. For monopole PCB antennas it is usually sufficient with a shunt component, as they can also be tuned by adjusting their length. As a consequence, it is in most cases a good idea to add some extra length for tuning purposes because the characteristics of your PCB are likely to differ from the ones of the DK's PCB.

So, in short, you should use the nRF52820's radio-matching network, in addition to the antenna's shunt component. The antenna should also have some extra length compared to the antenna found on the DK to facilitate the tuning of it.

Best regards,
Mathias