It is not uncommon for RV's to have a short coil of wire for a radio antenna. You'll often find this "antenna" hidden in the back of the stereo cabinet - along with the usual "bird's nest" of wires and cables. If you are looking for a roof antenna and can't see one, they didn't forget to install it where you think it should be. It's there - on the floor out of sight behind the stereo. New technology? More like a cost-saving measure I think.
You can try uncoiling the wire, and make a longer antenna by "stretching" it out and fastening it to a wall. See if that helps. If not, consider installing an external side-mounted antenna if the stereo is located in a convenient place. Or you can mount a roof antenna which will, of course, involve going through the ceiling.
2008 Cougar 5th Wheel 27RKS
2005 2500 GMC Duramax