Antenna's

I am completely brainless with all wifi issues. Here is my situation.

I am setting up an aux office in an electrical substation. My office will be in a metal building. I am about 600 yards from a wifi source. There are many obstacles in the path. By placing a laptop in the window I can adequately pick up a signal.
However when place on a desk, no signal. Tried a cheap antenna and it gave me one bar. Can anyone please suggest an antenna or fix for my problem.

I would recommend a wireless repeater. It's usually best to place it between the router and the point of access (substation).

Amped Wireless makes good repeater.

Newegg.com - Amped Wireless SR150 High Power Wireless-150N Smart Repeater

Thanks. that was the nice info...