Don't cover the device in tin foil. It'll just block the signal. The rod antenna has a coil in it at the base that picks up the signal from the small zigzag on the board. It feeds the signal to the rod and sends it on out. If you're not getting advertised range it's to be exspected. The advertised range is under ideal condistions. In the real world figure 3/4 to 1/2 that range.
All bluetooth products are meant for is short range device to device connectivity. A wireless headset for a cell phone doesn't need much range for exsample. This device is just so you don't have a wire from the router to the lappy or palm. Now if you're looking for some distance then check with other brand names.
Otherwise go out in a cowpasture 100 miles from town and you'll probabley get 100 meters. You probabley have a lot of radio frequency interferance around you where you are.