There is Miracle answer to this.
There are two options, they are a little costly ($50-$250) and
dependent on the environment they might, or might Not work. Thus returnable Hardware, and losing on restocking fees is part of the considerations.
Option 1.
Powerline hardware (example),
http://www.newegg.com/Product/Produc...82E16833122388
Option 2. Secondary (or more) Wireless bridging or WDS system.
Do you want the second Router to connect to the first one with cable and then transmit Wirelesslly?
Then do this,
http://www.ezlan.net/router_AP.html
Otherwise, you need a WDS (Repeater) configuration.
Start with One affordable Wireless Router that can do WDS (the reason to start with WDS capable Router is that in case you need to add more Wireless WDS hardware the original Router has to support it).
If you are lucky and your environment is conducive to get covered with one Good Wireless Router and you are done.
http://en.wikipedia.org/wiki/Wireles...ibution_System.
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This is an example for a moderately priced High Power Wireless Router that is good to start with, it does all the Wireless modes when flashed with the free DD-WRT firmware.
http://www.dd-wrt.com/wiki/index.php/Main_Page
http://meanderingpassage.com/2007/04...on-system-wds/
Using a Laptop loaded with Wirelessnetview, do a Wireless survey,
http://majorgeeks.com/WirelessNetView_d6102.html
According to the signal strength reading, identify spots that have strong signal. and spot with weak, or No signal.
Evaluate how you can cover the space and start placing WDS units.
Additional Wireless Routers in WDS Mode (Wireless Network - Configuration Modes. ) has to be placed in spots were the signal is good about Half way to the dead spots.
How many WDS units are needed? It depends on your specific environment (that is a good the reason to buying WDS units one at the time, try it, and decide on the Next step).
http://www.newegg.com/Product/Produc...82E16833162031