You need a better, more secure way to do it, like a radio ethernet link...
Then stick another wifi node on the end of that for local transmission...
Wifi was never meant nor designed to span huge distances, any solution you come up with using Wifi will be a cobble together and most likely be unreliable.

 

I built the parabolic reflector and it worked but was directional. Rather than that route it's far better to buy a ready made "gain" type antenna. I did that with a 2.4Ghz wireless video sender and it made a world of difference. They can be a bit pricey but they work, trust me!

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Don't make me reach through this monitor to slap you a good one!

 

You'll get further by simple re-routing the existing antenna, or like was mentioned before purchase a high gain antenna, these increase the effective transmitted power, but are directional. The only other quick and easy option is a wifi repeater, just google it. Or ask at your local big box PC store.

 

Actually, the easiest method is to see if your wireless router has a hack out on the internet. I have a linksys, and a simple google search shows many such hacks that change the internal firmware to boost the output signal. These units have variable output capability that is programmable internally, and there are those hackers out there that provide you the means to do this. I never did this to mine, but I researched it, and since I do not have any issues with signal strength, its a moot point. Perhaps you should look into this.

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"Everything that is done in the world is done by hope." -Martin Luther
"There are two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle."-Albert Einstein

 

I have done the parabolic and it works. Not a lot but it works. The Belkin repeater did not work. The high gain antenna works, but directional as stated.

So the cheap and wasy is get some foil and cardboard and start cutting..