Most of the major cable providers (in the USA) have apps that allow you to view live TV. I have Time Warner Cable, so there is a large selection of channels I can view on my iPad. They'd just upgraded it to allow some selected channels to be watch while outside of h]your house - but the majority can only be viewed while on your cable's feed (I.e. at home).
Then, there is also Slingbox, which allows you to connect to your home [cable] network. Or, ESPN offers some live TV options. Then, there's PlayOn TV that allows you to watch live TV. You have to put a program on your computer (that you pay for) and then you can use an app to stream live TV from your computer to your iPad.
But - as far as getting an app or connection that allows you to directly access TV signals, no, I don't believe there is anything like that. Sorry.
Marilyn