Being too far from your WiFi router causes a lot of frustration. Here I will show how I used three ways to extend a network together with tested success.
Step 1: Repeater Bridge
After mounting a yagi antenna I bought online for $25 I ran the wire inside to the Linksys Router. After a quick search I found that the router is one that is well suited for modifications. The site dd-wrt.com gives specifics on re-flashing and compatability with their open source (free) firmware.
Step 2: Firmware
Following the DD-WRT steps set the router up as a repeater/bridge. (this step is different for every router so checking the compatibility and downloading the most up to date and correct firmware is very Important.)
I did the same thing to make a wireless repeater for an ArDrone in this video.
Step 3: Connection to Router
I got a 100 foot long Cat 6 cable (eathernet or patch) and ran it from the renewed linksys router to this Netgear Router in my office. At this point having figured out how to flash a router I flashed this one also (not required.) I turned up the output power and melted the plastic a bit. so as shown a computer fan was added to keep things cool.
Step 4: Tuning
To aim the yagi antenna Start with line of sight just look down the antenna like a gun and get it close. Then find a program that shows broad band signal strength (I used a laptop and a the long cable before I ran it through the house) Fine tune the antenna to the highest signal strength and tighten the bolts.