What you’re looking for is an Over-The-Air (OTA) TV antenna. If you want to mount it o your RV King and WInegard are both great brands. Find the right one for you here: https://camperfaqs.com/best-over-the-air-rv-tv-antenna
Otherwise, any amplified TV antenna should work. You could just mount it to the ladder on your RV and run the cable through a window to your TV, for example.