AUX (pin 64) is a 50 Ω single-end auxiliary port that can be used to loop back the signal that is fed into the ANT pin. AUX can be used when two radios share an antenna. For example, when using a combined Global Positioning System (GPS) and LTE antenna, an internal RF switch in nRF9160 provides the needed isolation between the GPS and LTE paths.
AUX can be configured in software so that when the GPS receiver is on, AUX is connected to the ANT inside the System in Package (SiP). This enables the routing of the GPS signal from the shared LTE and GPS antenna to AUX and through a recommended external Low-Noise Amplifier (LNA) to the GPS input. To minimize mismatch losses, using external matching components between AUX and LNA is recommended. For more information on the antenna interface, see nRF9160 Antenna and RF Interface Guidelines. For more information on configuring the AUX firmware, see nRF9160 AT Commands Reference Guide.