There are some ideas for hidden antennas
here. You can be pretty elusive with outdoor antennas though. If you go to Ace or any hardware store you can find spools of copper wire of varying gauges. The higher gauge, the smaller the wire (you'd probably want something in the 20's). You can make a dipole with it or just string it out because almost anything outdoors is better than the best indoor antenna. However, if you live in a place with fierce winters it probably won't hold up unless it's on the ground. Good luck in whatever you choose to do and remember to tune into 6955 KHz on occasion (the active pirate radio frequency).