Antenna Installtion

Unanswered Question
Mar 7th, 2008

I was asked to attend a site to find out why their wireless runs at various speeds and signal strengths, if you take a look the image below you will see that the antenna has been strapped to a pillar (steel), now I believe that this will have an effect on the signal and quality but I need to find some official document from Cisco stating where antennas can and can not be located and what affect it would have being strapped to a pillar

Hope you can advise here please

Many thanks

Martyn

http://i254.photobucket.com/albums/hh91/chetty_2008/IMG_3306.jpg

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rob.huffman Fri, 03/07/2008 - 05:37

Hi Martyn,

You are most correct! This is probably the worst type of mounting location. The picture you sent looks like the Antenna is a Cisco 1728 Omnidirectional (360 Degree Radiation pattern). The whole backside will be almost completely blocked in this effort :(

Here is a clip from the 1728 docs;

Choosing a Mounting Location

The location of the antenna is important. Objects such as metal columns, walls, etc. will reduce efficiency. Best performance is achieved when transmit and receive antennas are mounted at the same height and in a direct line of sight with no obstructions. If this is not possible and reception is poor, you should try different mounting positions to optimize reception.

The antenna is designed to attach to and hang from a standard suspended ceiling track.

Cisco Aironet High Gain Omnidirectional Ceiling Mount Antenna (AIR-ANT1728)

http://www.cisco.com/en/US/docs/wireless/antenna/installation/guide/ant1728.html

Swing the Antenna out into the open and perhaps even add a second 1728 in Diversity mode and things will really pick up!

Hope this helps!

Rob

mcheatle Fri, 03/07/2008 - 05:45

Thanks for your reply and link, the Antenna is a 2506 which is wrong anyway as its a mast mount, was think if changing it out for a 4941 to see if this helps us out

ken.schindler Fri, 03/07/2008 - 11:38

From what I can tell by the picture, it looks like a warehouse or manufacturing facility. That being the case, I would strongly urge against the use of the 4941 antenna. That would be fine for a small office environment. The 2506 would work better if you were able to get it off of the column. Hanging a piece of unistrut off of the column and moving the antenna out a couple of feet would greatly help. An antenna that I have had great success with in manufacturing and warehouses is the AIR-ANT3213 (with a little mounting modification). You would want to move this one out from the column also.

One more thing to check. If you are only using one antenna port on the radio, make sure the other one is turned off. You will see fluctuations in signal if it is not.

Good luck

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