A dish is a type of antenna, but "OTA antenna," in whatever form, is used specifically for reception of Over The Air terrestrial television broadcasts.
You can connect another dish (satellite antenna) with a DP LNB to pick up a 4th Dish satellite slot.
You can not connect an OTA antenna to that input. If you need the sat and OTA feeds to share coax, you must combine them on the switch's receiver output using a diplexer.