The nRF52840 DK is equipped with a small coaxial connector (J1) for conducting measurements of the RF signal using a spectrum analyzer.
The connector is of SWF type (Murata part no. MM8130-2600) with an internal switch. By default, when no cable is attached, the RF signal is routed to the onboard trace antenna.
A test probe is available (Murata part no. MXHS83QE3000) with a standard SMA connection on the other end for connecting instruments (the test probe is not included with the kit). When connecting the test probe, the internal switch in the SWF connector will disconnect the onboard antenna and connect the RF signal from the nRF52840 System on Chip (SoC) to the test probe.
The connector and test probe will add loss to the RF signal, which should be taken into account when measuring. See the following table for more information.
| Frequency (MHz) | Loss (dB) |
|---|---|
| 2440 | 1.0 |
| 4880 | 1.7 |
| 7320 | 2.6 |