A friend of mine decided to cut the cord so I helped her buying and setting up a Roku stick. Today she called to tell me that show bought one of those HD Antennas that are always advertised on TV. I told her to cancel the order ASAP or return it if she can not do that. This article link will explain things better, but if you do decide to cut cable and get an antenna do not fall for the "HD" antenna scam. Heck, if you still have an old outdoor antenna connected to your roof that should suffice. If you do need a new antenna, a little research online should help determine your antenna needs. A lot depends on where you live.
https://www.techhive.com/article/3315108/antenna-myths-busted.html
https://www.techhive.com/article/3315108/antenna-myths-busted.html