Thread: WiFi Roof-rack

If you mount an omni horizontally, you will have very limited range, as omni antennas are vertically polarized with a horizontal beam eminating 360 degrees with a virtical beam width of approximately 25-30 degrees.

Without getting too technical, you will basically have great range directly to the left and right of the vehicle, but not forward and in back of the car. If you mount it running across the car, you will have coverage to the front and read, but not the sides. I would recommend instead you buy one of the low profile ceiling mount style antenna (usually about 3.5dbi gain) and mount it in the center of you rack on the roof of the vehicle so you will have 360 degree coverage, and about a 35-45 degree verticle beam width as well.


Hope this helps

You could, but a 2.4ghz duplexer is not cheap. You can expect to spend about $150 for a quality one. If you are willing to spend the money, I would get a 1 watt amplifier, some quality connectors, a nice weather resistant ceiling mount omni (you can airbrush it to match your paint) and use the shortest cables possible. This will usually put your EIRP at the legal limits, and greatly increase your effective range.

As far as the omni, you pulled up a direcctional patch antenna, try this link http://www.hyperlinktech.com/web/hg2403cu.php

As far as a duplexer, it is also refered to as a splitter or signal combiner. Here is a link http://www.hyperlinktech.com/web/sig..._2400_2way.php but remember you will loose about 2-3.5 dbi every time you split the signal, not to mention with those antennas you linked to, you need to have at least 6 feet of separation for diversity, or you will have high data error rates. Also, at those prices, you could definately afford an amp. http://www.hyperlinktech.com/web/ha2401dx_agc.php is a good example of a quality 1 watt amp, which can be often had for about 260 from other vendors.


Let me know if you need any technical details or additional information

for every 3dbi you increas your power, you double the range of your equipment. (Logarithmic scale) Take the output power of your device in mw, calculate your line and connector loss, add in any amplifiers you may have, then add your antenna in. Take the final falue and convert it to db, which you can then get an approximate range from.

Examples (Depends on your surroundings)

30mw ~150-200 ft
100mw ~ 300-350 ft
500mw ~ 850-1000+ ft
1 watt ~ 1500+ ft

What kind of PC are you putting this into, do you have an open PCI slot, if so I would reccomend this http://www.netgate.com/NL2511.html and add a PCMCIA to PCI adapter. It has a higher trasmit power which will give you much better range.