Outdoor Coverage

Unanswered Question
Aug 4th, 2010

Hi,

I have a requirement of Wi-Fi coverage outside of the building, currently i am planning to deply 1250 series AP (2.4 & 5Ghz)

how to achieve outside coverage keeping the Access Point inside the building,

will the External Antenna solve my problem if yes, what model of antenna is preferred for the same.

Thanks in Advance.

I have this problem too.
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dennischolmes Wed, 08/04/2010 - 04:37

You can use the 1252 as an outdoor AP for 11n but Cisco suggests the use of the 1500 series MESH APs. An 11n version is due for release pretty soon. If you opt for the 1252 I would suggest mounting the AP outside as well with a weatherized NEMA enclosure. Remember that any use of cables to the antenna does result in some signal loss. Compensate with antenna gain. I have a specialty antenna that I use.

kiran@wipro Wed, 08/04/2010 - 04:52

Thanks for suggestion.

but my requirement is stright that I need to place Access point Internally and extend the antennas outside, so I am looking for External Antenna which suits 1252 Access Points also maximum outside coverage.

I had a research on the cisco site, but i could not find much...

http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008022b11b.html

let me know if you guys have some other alternate to these antennas

Leo Laohoo Wed, 08/04/2010 - 05:16

You have a number of choices:

2.4Ghz
AIR-ANT2430V-R (ceiling mounted) or
AIR-ANT2460NP-R (wall mounted patch)

5.0Ghz
AIR-ANT5140V-R (ceiling mounted) or
AIR-ANT5160NP-R (wall mounted patch)

Please don't forget to rate useful posts.  Thanks.

dennischolmes Wed, 08/04/2010 - 05:55

Leo makes some good suggestions from the Cisco portfolio but I would call Tessco and some third party vendors who specialize in atennae. My experience is that you need a more specialized antenna for outdoor uses.I use the Tessco 354980 2.4/5ghz omni 6dbi outdoor omni. Easy to mount.

kiran@wipro Wed, 08/04/2010 - 23:26

I don't know will I be able to use External vendor antennas apart from Cisco,

anyway i went thru that model its good to go, but I would like to know what is the distence it covers?

Leo Laohoo Wed, 08/04/2010 - 15:49

I am looking for External Antenna which suits 1252 Access Points also maximum outside coverage.

What is the dimensions of this "outside coverage"?
kiran@wipro Wed, 08/04/2010 - 23:20

Thanks for your reply,

I am looking to cover 15 to 20 meters outside coverage,

Keeping the normal Antennas attached to 1252 AP inside the building wall will help me to achieve outside coverage distance ?

let me know any alternate solution if you find

Leo Laohoo Thu, 08/05/2010 - 15:23
I am looking to cover 15 to 20 meters outside coverage,

This is not enough.  This is just either the distance or the width.

Keeping the normal Antennas attached to 1252 AP inside the building wall will help me to achieve outside coverage distance ?

Again, more information please.  Your first post said that you want external antennaes now you want "normal" antennaes.  Can you elaborate further.  What type of wall do you have that separates the inside and outside?  How thick are the walls?  How do you expect to install the AP?

Please elaborate further because we are techno guys/gals.  I just want to let you know that I (and some of us) flunked "Mind Reading" classes several times. 

kiran@wipro Thu, 08/05/2010 - 22:51

I am placing my Access Point 3.5 mtrs above from the ground lvl,

20 meters which I am talking abt is the distance from the outside of the building.

I just wanted to know will I achieve this outside coverage with normal antennas or not ?

I am planning to place my AP near the wall and thickness of the concreate wall is around 40 cms, we have such kind 2 walls

AP normal antennas should pass those 2 thick concreate wall (40cms) with some metal disturbance(AC duct), after these 2 walls I am looking for 20 mtrs coverage around the building.

depicted a diagram for better understanding :)

Leo Laohoo Thu, 08/05/2010 - 23:06

Antennas transmit and receive radio signals which are susceptible to RF obstructions and common sources of interference that can reduce the throughput and range of the device to which they are connected. Follow these guidelines to ensure the best possible performance:

•Install the antenna vertically and mount it with the cables pointing towards the ground.


•Keep the antenna away from metal obstructions such as heating and air-conditioning ducts, large ceiling trusses, building superstructures, and major power cabling runs. If necessary, use a rigid conduit to lower the antenna away from these obstructions.


•The density of the materials used in a building’s construction determines the number of walls the signal can pass through and still maintain adequate signal strength. Consider the following before choosing the location for your antenna:
–Signals penetrate paper and vinyl walls with little change to signal strength.
–Signals penetrate only one or two solid and pre-cast concrete walls without degrading signal strength.
–Signals penetrate three or four concrete and wood block walls without degrading signal strength.
–Signals penetrate five or six walls constructed of drywall or wood without degrading signal strength.
–Signals will likely reflect off a thick metal wall and may not penetrate it at all.
–Signals will likely reflect off a chain link fence or wire mesh spaced between 1 and 1 1/2 in. (2.5 and 3.8 cm). The fence acts as a harmonic reflector that blocks the signal.


•Install the antenna away from microwave ovens and 2-GHz cordless phones. These products can cause signal interference because they operate in the same frequency range as the device to which your antenna is connected.

dennischolmes Fri, 08/13/2010 - 05:24

So, what Leo is basically saying here is that when going through a wall you lose signal. How much exactly depends on the wall. What I am saying is that I would not count on gaining dependable and reliable coverage when going through an external wall and expecting to get 20 meters of reliable coverage. The math doesn't make sense. Every 3db of loss is equal to half of your transmitted power. So, let's say the wall is 6 db loss and you started out with 100mw (which you shouldn't) but for example. The effective power on the other side of the wall if the antenna is only 5 feet away from the wall would be roughly 25mw. The AP will probably be able to punch through the wall but the client device likely won't be able to get back to the AP due to poor antenna design and a lower powered radio. Mount your antenna outside or the AP in a NEMA weatherized enclosure along with antenna for outdoor coverage is what I am saying. It's the only way to guarantee coverage. Site survey it with an actual AP and see what you get. You will be surprised. Don't just look at signal strength. Look for reliability and fade. Stable SNR is what is required for a good link.

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