I live in an apartment and use an outdoor antenna.....but what I do is have it on 7" of fencepost set into a 50-gallon drum, cut down in half (so it's more like a 25-gallon drum) filled with concrete, for weight. Thus, instead of mounting the aerial somewhere permanent, like on a balcony rail or the side of the building, it's completely portable. I can just set it outside on the balcony and bring it inside if I have to, for maintenence or whatever reason. Weighs about 350 pounds, but it's very convenient e.g. if I need to adjust it so KOPB and KGW come in better! ;o)
It's also good since I use satellite, I can stick the dish on the same mast about half-way up. Works beautifully.
As for a "permanent" installation, e.g. mounting it to the building: according to the manager, in his words, that's "a big old no-no." In fact, the manager of another apartment took the same stance, but also told me about the concrete drum thing. So that's what I have done since......
Now, as for DXing, I use my Grampa's Pioneer SX-1000W stereo receiver with a long, LONG piece of speaker wire (about 30') running up the wall and along the ceiling as my antenna! I can regularly get KXXO on 96.1 using that setup, relatively static-free, and sometimes even sounding like a local. ;o)