Rene, yes, I've looked in the bedroom cabinet where the cable comes in, in the built in entertainment center, even in my basement compartment, where the 3rd cable is... nothing...weirdWelcome to the forum.
Is the antenna above the bedroom?
If it is, Do you have a spot all set up to hook up a TV? Usually the switch will be right there at least in the rv’s I’ve owned.
Is this just a new to you RV? If it is, contact the dealer or seller
Here's a couple of picsWhat antenna is on the roof. Some don't have a built-in amplifier. Show us a picture of your antenna. Some,like the King Jack, the switch is in the ceiling mounted directional control.y
Another thought. If you have an input selector for selecting the source (antenna, cable, DVD, etc) the switch may be there.