You do need an OTA antenna. Since you live in LA county you will have a way more stronger signal strength than what I have, although I have between 80-95 signal. That would include channel 4.2,4.4,5,5.2,7.2,7.3,9,13,28.1,28.2,28.3,28.4. Those are just a few that I watch most of the time. There are still others that may interest you, and many more. As you can see some channels have .2,.3 what that is, is a sub channel within a channel.By the way if you compare a OTA signal with dish the antenna quality still beats HD over dish because you are getting it direct from the station. Hope this is enough information.:up