Hey,
I have been looking into the same issue recently and found the following link from another (more recent) Ask the Experts session with Fred Niehaus:
https://supportforums.cisco.com/message/3371927#3371927
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The antenna array on the AP-1142 is based on an inverted "F" type design and are mounted on a metal plate. It was designed this way so the radation pattern when mounted on a ceiling forces the signal to go downward and outward in a 360 degree fashion. So it works best in that configuration especially for high density deployments. Now when you take the device and mount it on a wall, it is recommended that use a third party mounting structure like the Oberon 1029-00 right angle mount at www.oberonwireless.com
If you choose to simply mount the AP directly on the wall, you can do this and it will work fine for hot spots, but the signal will be leaving the Access Point (in a forward direction) and also radiate UP and DN the issue really comes in with larger installations as there is a possibility of some coverage on the ABOVE and BELOW floors so potentially in a dense area a WI-Fi phone would roam more often (hitting pockets of areas of unintended coverage) which is why we recommend the Oberon mount.
Again, smaller venues, kiosks, bus, train, hot spots in a home etc., there is no reason why you cannot mount it directly on a wall.
- See more at: https://supportforums.cisco.com/message/3371927#3371927
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The 1140 Data Sheet states the antenna is 360 degree horizontal beamwidth but fails to mention the vertical beamwidth:
http://www.cisco.com/en/US/partner/prod/collateral/wireless/ps5678/ps10092/datasheet_c78-502793.html
If you look at the antenna pattern guide as the other forum posts say you'll see the vertical beamwidth is 120 degrees and not 360 degrees so surely that means omnidirectional is only realistic at lower powers?
http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html
I've concluded the following from my research across the various links:
- "F" Type antenna patterns are 360 (horizontal) by 120 (vertical)
- Ceiling mounting your WAPs (1142/3502i/3600i etc) is preferred especially when in a multi-level deployment as it will reduce cross floor interference.
- High density multi-level deployments in particular will benefit from ceiling mounted WAPs
- The higher the power of your WAP equals a 'flatter' donut shape eminating outwards from the WAP on the azimuth plane
- At lower power if you have wall mount versus ceiling mount the differences may not be as acute due to the donut shape becoming more ball like (try and picture it in 3D).
- Using Oberon L shaped wall mount is a cost effective way of angling your APs without having to cable up to the ceiling - http://www.oberonwireless.com/WebDocs/Cisco_Solutions.pdf
I'd appreciate any feedback on those thoughts as this seems a particularly essential thing to understand accurately when designing a Wireless network.
Thanks,
Ric
