it requires an external antenna, i think the antenna attaches to side of the radio on left, but not sure if i am correct. i was told by installers that middle connector is for the subwoofer, but the radio should still work without the subwoofer if you vehicle didnt come with one... my question those does anyone know if the navigation have a built in mic cause i plan using my cellphone with the unit cause hawaii just got a stupid cellphone law where if we are caught we have to pay 125 fine for talking on the cell