Yes, the radio antenna is an entirely different deal. Sunline used the following antenna for quite a while. At one time, it was mounted on the side instead of the roof, but most are on the roof. If your coach didn't come with a built in radio, it won't have an antenna. Roof mounting might be a little easier as long as you properly seal around it.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR