While you can buy any HDTV antenna from the plentiful options available at your local electronic and/or department store, you could always build your own. Here’s the kicker: this do-it-yourself project actually looks nice enough that you would want to hang it in a window, PLUS it’s powerful enough to pick up over-the-air HD channels in your area. The best thing about this option is, of all things, it’s really cheap to make.
This particular custom HDTV antenna comes from HTPC DIY, and is mostly transparent and good-looking enough that you potentially could put it in an apartment window without blocking too much (if any) of the view or draw any attention to it. The materials you’ll need to get started include: paper, aluminum foil, flexible plastic (i.e., document covers—you can find them at any office supply store), a matching transformer (plus the nuts and bolts necessary to mount it), and some glue. When you done, you’ll have a powerful fractal antenna that might rival some of the commercial options you’ve seen before, but at only at a fraction of the retail price.
If you want to make one yourself, click the link below for a complete walkthrough. It’s a relatively quick project you could get done in a few hours on any given weekend, and your prize is free over-the-air HD (as long as you’re in range you’re in range) straight to your TV.