An antenna is just an electrical conductor. If it'll conduct electricity it can be used as an antenna. An antenna for HF is a fairly simple thing to make. It should be able to be plugged into the receiver and run at least sort of inconspicuously. If you place that receiver close to a window, just run a wire out that window and throw it over the house/building (if possible). Is there a metal screen on that window? Okay, make it part of the antenna, won't hurt a thing. Stay away from things that already have electricity in them! House wiring, power lines, that sort of thingy. Just not a good idea, you know? After that it's a matter of what you happen to have handy and your imagination.
- 'Doc