Hi Michael,
Thanks for the information. Often, the backs of computers are full of radio interference, because they are not well shielded from the many devices inside the computer that are emitting radio waves in the same frequency band as Wifi.
This can especially be a problem with USB 3.0 ports, which sadly Intel discovered put out a lot of interference after they already put them on the market. Here is a white paper they wrote about this:
http://www.intel.com/content/www/us/e…
Are you using a USB 3.0 port? It would be better to change to a USB 2.0 port if possible, preferably on the front of the computer.
Better yet, a standard six-foot (2-meter) USB 2.0 extension cord would be great (like this: http://www.amazon.com/dp/B00NH136GE), since you can use it to raise the adapter away from the computer, while the fact that it is USB 2.0 will keep it from emitting the interference from the far end, even if it is plugged into a USB 3.0 port.
I hope this helps. If not, let me know.
David