The single-ended antenna output (ANT) of the nRF5340 System on Chip (SoC) is connected to an RF switch (U17), which allows you to select either antenna A1 or antenna A2. The RF front end allows the nRF5340 SoC to transmit using only one antenna at a time, that is, A1 or A2. It is not possible to transmit with both antennas at the same time. The antenna selection is controlled through the SEL pin (P1.10).
Antenna A1 is connected to the ANT1 port of the nRF21540 RF FEM, which is connected to the RF1 port of the RF switch. The nRF21540 RF FEM supports TX output power gain up to +20 dBm on the A1 antenna. The A2 antenna is connected directly to the RF2 port of the RF switch. The maximum TX output power supplied to A2 is +3 dBm.
The following table shows antenna gain over frequency for the A1 and A2 antennas.
| Antenna | 2402 MHz | 2440 MHz | 2480 MHz |
|---|---|---|---|
| A1 | +1.10 dBi | +1.15 dBi | +0.55 dBi |
| A2 | –0.17 dBi | –0.11 dBi | -0.20 dBi |
The following schematics describe the antenna selection.
