The range you are experiencing seems much less that I would have expected. Is it possible that by going outside you are wandering into the influence of another network on the same channel? NetStumbler can be a helpful tool in these problems.
I use a magnetic base antenna from Jaycar (their cat number AR-3273) to extend the range of my system here. Its use assumes that your router has a removable antenna and that the cable from this device can be screwed onto the router wireless socket. They also have a higher gain version at increased cost. The advantage of these external antennas is that it may allow placement of the antenna in a better location, and it also makes experimentation with corner reflectors and other devices of this kind mentioned by others that much easier and perhaps aesthetically a little more acceptable.
My wireless signal goes from my Billion router through two house walls (one internal, one brick veneer - both without foil) through to a WAP inside my shed with acceptable signal strength. I have the Jaycar antenna on the WAP - the combination works better in that configuration for this situation. In most instances - like yours of course - it needs to be fitted to the wireless router itself.
One last point. Some routers have the option of varying the wireless output power. Check the manual for yours, and if this option exists, get into the menus and see that it is operating at maximum output.
Good luck
Terry
FOR
Last edited by FullOppositeRudder; 25th May 2010 at 05:25.
Reason: surplus apostrophe spotted and put to rest ...