Diversity Antennas

[agent007]

I'm using a Cisco PC 11b card with no provided antennas. If I mount two small omni's, one vertical and one horizontal within about 8 inches of each other, will it improve rx/tx? And what is meant by separating diversity antennas by a wavelength???

Also, my 11b WLAN's sole purpose is to connect a remote client to the Internet via a T1. Since the T1 is only 1.5Mbps, will matter if the client is set to 11, 5.5, or 2.2Mbps? I can probably increase the performance of the WLAN by keeping the rate lower.

I'm sooooo confused!!!

[N1XRR]

I don't know too much about wireless networking technology, since I've just started playing with it, but I have been into radio communication for 5 years or so.

What type of antenna do you have?(brand/model) or is it home-made? Diversity, dunno much about that type...but what I can tell you is gain and height are what really matters. A higher gain antenna(more db) has a better effective radiating power than a lower gain antenna. Also, the higher you go, typically the better(to get out of the way of potential sources of interfearence)

How did you come up with "seperating diversity antenna's by a wavelength"? I don't remember exactly what the equation is, but I can tell you its along the lines of 10cm or less, I'll do some calculations later. Does it have to be exactly a wavelength? Or just more than a wavelength?

Also, the WAP and NIC's should auto-adjust for the fastest supported speed. And 2.2mbps will be plenty fast enough for T1.

Michael

[agent007]

Thanks for the reply. As for the wavelength issue, I asked some folks at Maxrad, mfr of the 4dbi antennaes that I have. My home 802.11 has two antennas for diversity, and I wanted to mount two on my mobile setup as well. I think I'm just gonna have to play with it (the antennas that is) to see what works best.

[mupdike]

The purpose of diversity antennas is to eliminate multi-path interference from the network. The question is, does your NIC have an input for an external antenna to allow for one, let alone two. As for the orientation (vert/horiz) you would want to keep that the same as your access point. Usually, there is not really any need for a client to have diversity antennas, but if you have the ability to add it (i.e. multiple inpuits on your nic) you should notice a small improvement in areas where there is much interference.

The other part of your question is about the speed of the WLAN, remember that your throughput will only be approx half of your connected spped due to the overhead of 802.11b. This means that if you connect at 2.2 Mbps you will get only 1.1 MBPS throughput. The question on this is why do you think that keeping your connected rate lower will improve your performance? " can probably increase the performance of the WLAN by keeping the rate lower. "

Good luck,
Mike

[NewBWiFiGuy]

I plan to lower the data rate in my APs until I can find bandwidth control options (http://forums.80211-planet.com/showthread.php?s=&threadid=1071) to restrict my customers to what they pay for.

In the Linksys Wap54G I know there is support for different transmission rates. 1, 2, 5.5, 6, 9 , 11, 12, 18, 24, 26, 48, 54. I may limit people to 2mbit for a while.

I am not aware of any downfalls to setting your transmission rate lower. Anyone?