Originally posted by: Kaido
For example, this antenna for a Buffalo wireless router from Buy.com:
http://www.buy.com/retail/product.asp?s...9366&Type=PE&Category=Comp&dcaid=17379
Do they actually improve range?
While that specific antenna isn't going to give you much in the way of gains, a higher-gain model certainly will. $35 for a 4dBi antenna is borderline highway robbery.
I've had excellent luck with Hawking antennas, which tend to be cheap and powerful. There are lots of resources on the web for DIY antennas. Contrary to some of the information on EZLan.net, a stronger antenna on your router can make a significant improvement to the coverage of your wireless signal.
My personal favorite is this one from Hawking:
http://www.microcenter.com/single_product_results.phtml?product_id=0213239
It's $30 for 6dBi. That's more than a two-fold improvement over a stock 2dBi ducktail that a typical router has. Now, a 100%+ signal improvement doesn't translate 1:1 to distance improvement, but I've used these to increase my effective coverage radius by, at BARE minimum, 40%, averaging around 60% or so.
Also, you can make cheap and simple parabolic reflectors for an antenna as a two-fold measure to decrease signal propagation in one direction and increase signal strength in another. An antenna with a parabolic dish made from aluminum flashing can expect a 6dBi increase over the antenna's unreflected power. Therefore, a 6dBi omni-directional antenna ($30) with a 6dBi reflector ($5 in materials) becomes a 12dBi Directional. It's not exceptionally pretty, but cheap rarely is. But it works.
I'm working on a tutorial for making one (the site that used to have one online, freeantennas.com, seems to no longer exist) out of aluminum flashing, which is a lot more effective than aluminum foil, but in the meantime, check out this site:
http://www.binarywolf.com/249/diy-parabolic-reflector.htm
This is only effective, of course, if your wifi access point is at the edge of your signal coverage area, allowing you to bask the rest of your area with the signal. For example, position it in the front room of your house, pointing to the back, so that the whole house plus the backyard gets wifi. You'll have spotty access on your porch with this method though.
There's a lot of fun to be had playing around with different antenna designs, and you can make some wicked stuff depending on your level of craftsmanship. Just google for "diy wifi antennas" and you'll get started quickly.
