You can select multiple options for Radio Communication, Navigation and Approach aids, on the Aircraft page. In the Radio Communication section, choose:
S if your aircraft has a VHF comm radio AND a VOR AND an ILS receiver installed (all operational.)
G if your aircraft has a GPS receiver that is installed and operational.
If your aircraft has a G1000, you could select both S and G. Same goes for a GTN750, KSN770, GNS430, etc…; each would allow you to select S and G. However a handheld or portable GPS does not allow you to select “G.”