Is it a digital TV? Because if it is, those generally either get a picture or they don't. Snowy partial pictures went out with analog TV's. Is it digitizing, like breaking up in little dots, gone for a minute or freezing and comes back? That is typical for a digital TV with a borderline signal.
First thing I would check is inside the camper, most likely behind the main TV, there will be a plate on the wall with your antenna cable running into it. It should look something similar to this:
Make sure that little button is pressed in and there should be a light that lights when it is on. That is your signal booster and needs to be on when you are watching over the air TV and off if you are watching SAT or Cable TV.
Check that out and let us know and we will go from there.
2020 Chevrolet 2500 LTZ, 2019 Forest River Wolfpack 23Pack15, 2014 EZGO Golf Cart.