nRF9160 supports testing antenna presence based on the DC current flow.
Antenna presence can be tested with the Nordic-proprietary %XANTDETMAGPIO AT command. The command reads the status of the MAGPIO pin and reports the detection based on the DC grounding of the antenna feed pin. The antenna is considered detected when the pin is grounded.
For more information on the %XANTDETMAGPIO AT command, see Antenna detection test %XANTDETMAGPIO in nRF91 AT Commands Reference Guide.