I'm evaluating an OpenThread mesh network in a large warehouse and considering the nRF21540 Front-End Module (FEM) for the router devices. To test this setup, I purchased two nRF21540-DK boards and two nRF52840-DKs, allowing me to configure four boards using this FEM IC. My setup includes:
- 2x nRF21540-DK (integrated nRF52840 SoC with nRF21540 Front-End Module (FEM) IC on a single board)
- 2x nRF52840-DK with nRF21540-EK shields (requires an RF cable to connect the RF connector on the nRF52840-DK to the SMA connector on the nRF21540-EK shields)
When connecting the nRF21540-EK to an nRF52840-DK, a question arises: how should the RF output from the nRF52840 SoC connect to the SMA connector on the nRF21540-EK? The SWF connector on any Nordic's BLE/802.15.4 DKs seems not to be solely for RF measurement purposes (e.g., for spectrum analyzers). if the goal is to connect the SoC RF path to the SMA connector on the nRF21540-EK, the choice of an SWF connector might not have been ideal from Nordic.
Nordic has equipped all their development kits (DKs) with a Murata SWF connector, where each SWF-to-SMA cable costs at least $30. After purchasing the two nRF21540-DB boards to set up four boards with this FEM, I now face an additional $60 expense for two cables to connect the RF path to the nRF21540-EK shield.
Is purchasing this cable the only solution? Nordic should definitely reconsider its use of SMD connectors, which require specialized and costly adapters and cables.
