Many USB wireless adapters have very good electronics paired with rather poor antennas. While these devices are adequate for very local networking, they are capable of much better performance when connected to a high quality external antenna. The Belkin F5D7050 is commonly available yet can give uncommon range and speed performance with the modification described here.
Note: If you can't find this wifi device, there are newer high power wireless adapters and routers available. Get a new one, and connect!
Here is a project that can greatly increase wifi connection speed and range. It can be applied to just about any commonly available adapter; one simply cuts out the built in antenna and runs a feedline to a high gain replacement. I have seen throughput on a 30 meter path go from 5.5 MB/Sec to a solid 54 MB/Sec - with reduced interference and no need for amplification. Note that longer path lengths (more than 200 meters or through walls and vegetation) may require making this modification to a device higher powered than the F5D7050.
First, look at the circuit board. It boasts an efficient and clean layout. Data passes through the USB port on the left, and the antenna is etched on the right side. This modification is not difficult, but bright lighting and use of a magnifier is suggested due to the small surface mount parts and thin circuit traces on the adapter. It is a small work area, so use caution.
F5D7050 Modification Procedure:
Above is an example of the modified F5D7050 and external antenna in operation. Some aiming will be necessary to peak the signal and maximize data rates. Performance of this USB wifi adapter went from good to outstanding with the added external antenna.
Note: This modification is quite similar to the one for the Linksys WUSB54GC. Look at that page, and become familiar with the general concepts adding an external antenna to a usb wifi adapter or wireless router.