Wireless Antenna Question

[rx33328]

Hi -- We are using Aironet 4800 AP's thoughout our factory. I have been told that you should not attach different antenna's to the same AP. In other words, do not attach a dipole antenna on one side and a patch antenna on the other side(both should be the same). Has anyone had experience with this.

[fjuch]

The reason for this is the AP is only connected to one antenna at a time. The purpose is to switch antennas when a reflection or echo is detected in the received RF signal. If you have different antennas user A may be in antenna (pattern) 1 when the unit switches antennas to hear user B on antenna (pattern) 2. This could leave user A with no coverage at all. The worst case would be beams pointed in different directions. To use different antennas on a single AP to increas range is not what the unit was designed to do, and will probably cause other problems also. It is possible to disable one antenna port if you do not want to purchase two antennas. I think this is not a place to cut back though.

Good Luck with the project.

[jeff]

Dual antennas are meant to reduce the probability of a condition known as "multipath". Multipath is caused when reflected signals of an RF transmission reach a receiver out of phase and cause distortion of the signal or in phase and cause an unnatural strengthening of the RF signal. Both of these can cause throughput issues on the wireless LAN. You want to use omnidirectional antennas ONLY. Also, an AP only transmits or receives from one antenna at a time, and it transmits out of the antenna on which it last received a transmission. So, if you had an omni on one side, and a directional on the other, and client1 sent a transmission which was picked up on the omni meant for client2 which is only in the range of the directional, client2 would not get the transmission because it would be sent right back out the omni. If you would like some training in this subject, go to www.cwne.com. Hope this helps.