I use a mud flap antenna at home and I have a slim line (2inches x 24 inches) in the motorhome.
I bought both at WalMart, the Mud flap will also work in a MH and costs about $60, the slim line costs about $25. I have good reception on both, although with the slim line in the MH I have to reprogram at every location. Which is no problem you just press a couple of buttons and the TV does the work. I generally receive between 20 to 30 channels depending on where I am. But you have to remember, ITS free no annual or monthly fees.
There is also a ad on TV at the moment for Clear View which does the same as the Mud Flap..
The old rabbit ear antenna also works and costs about $10...
Enjoy....