Need external antenna for WRT54GL

for antenna info.

Best output is the 100 mW (20 dBm) and run a 16 dBi gain omni antenna. This will meet the 4 watt (36 dBm) maximum ERIP. Also, the Linksys does not deal well running at more power at its max of 250 mW.

Opps...you want a directional antenna. Still keep the output at

100 Mw and use a 36 dBi 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.

Cheers, Steve

DTC hath wroth:

You only need or want one directional antenna. The diversity switch will do weird things if you have two different types of antennas or tow directional antennas with divergent patterns.

As to which is the most appropriate directional antenna, I dunno. You haven't mentioned what you're trying to accomplish. Different antennas do different things.

Some detail. The maximum output power varies with the antenna gain for a directional antenna and point to point system according to this handy table:

Ant Tx Pwr EIRP EIRP dBi dBm dbm watts 6 30 36 4 9 29 38 6.3

12 28 40 10 15 27 42 15.8 18 26 44 25.1 21 25 46 39.8 24 24 48 63.1 27 23 50 100 30 22 52 158.5 33 21 54 251.2 36 20 56 398.1 39 19 58 631 42 18 60 1000

However, for an omnidirectional antenna, you're limited to +36dBm EIRP or 1 watt into a 6dBi omni antenna.

I'll have to look up the link to the pdf as its not obvious on the Andrew's website. Its part of the terrestrial microwave line. They run around $3,400 to start, not counting radome or shipping.