I have a WRT54GL flashed with dd-wrt and I was wondering what would be good directional antenna to buy. Should I buy 2 antennas for each output or just one? Which is the best output to use if I only need 1 antenna?
Got any links for a 36 dbi antenna? I imagine you're just passing the legal numbers on!
Anyway, to answer the questions, many directional antennas will work well but the question is; what is your intended use? Is it to be mounted indoors or outdoors? Go to a dealer's site and select indoors or outdoors and then look for a gain pattern to tell how tightly focused the antenna is.
I imagine many people just go for the highest gain, but that could be a mistake for many reasons. For one thing, the gain patter is grows narrower as the gain goes up and you lose coverage and intensify interference.
I had an application where I needed to connect to various clients located over a 60-80 degree range horizontally and a 40 degree range vertically. It was more important to get everybody covered than to have the highest gain.
I settled on a small 12 dbi panel antenna with a wide 60 degree beam width. It has served us well and even connects at longer distances (600 meters) with line of sight.
Panel antennas are commonly used and range from 12 - 19 dbi. This is a good middle ground but again, check the pattern against your needs.
Parabolic reflectors are also commonly used. There's a nice little 14 dbi reflector antenna called a "Backfire" that comes recommended:
If you need long distance (caution: 8 degree beam width is tricky to aim - pinpoint precision), you can go with a larger, high gain parabolic grid antenna:
If you are going with interior antennas, then your options or more limited, typically panels, which should work fine. Hawking has an interesting corner antenna that is worth looking at. (No links.)
Whatever you choose, use low loss coax cable to connect, specifically LMR400 for anything over 10-12 feet. Don't settle for cable over a foot that does not have a number. Don't buy the cheap department store (or Ebay) antennas that come with six feet of crappy cable attached. This cable eats up most or all of the gain.
If you just need an improved directional signal inside your house, consider putting a reflector on your stock antenna(s):
This can really work.
Finally, you do not need two antennas, you can use one side of your Linksys and disconnect the other, disabling it in the router interface. I used the right side as you face the router, but may be mistaken on that.