Aironet 1252AG Weak Signal

Answered Question
Aug 25th, 2010

I've an AIR-AP1252AG-A-K9 and three AIR-ANT5160V-R 5 ghz omnidirectional antennas.  It's mounted on the roof of a 1,800 sq ft footprint, 3-story, wood-frame construction building.  It's powered by a POE injector and reports Normal (Full Power). 

It's a new installation, my first time working with this equipment, and I'm baffled.  The 1252's  broadcast range appears to be miniscule.  Cisco assured me it would blast the building, suggesting I'd probably want to tone it down.  I've worked my way through every configuration I could imagine might be relevant, and can't get a signal unless I'm standing on the roof within 20 feet of it.  The slightest obstruction degrades the signal and it takes almost nothing to block it entirely.  It's unusable outside of short-range line-of-sight.

To give an idea of what penetration is normally like here, there are already a dozen wifi routers of assorted small-beans ilk in the building.  I get a strong signal anywhere from nearly all of them.  Ironically, the point of the 1252 is to eliminate this ridiculous redundant mess, but it's being outperformed by the garbage it's intended to replace .  I've a little NetGear in the approximate center of the structure which gives a decent signal in the basement parking garage, on the roof, at either end of the building, and across the street, but I can only connect to the Aironet if I stand on the roof and look at it.

What am I doing wrong?  Have I bought the wrong equipment, or (preferably) am I just an idjit who's missing the obvious?

Thanks much,

Bryan

I have this problem too.
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Correct Answer by Leo Laohoo about 6 years 3 months ago

Somewhat confusingly, it doesn't appear in the "Aironet Antennas and Accessories Reference Guide."  I found it by accident, which makes me wonder what else I might be missing.

There have been numerous requests to get the documentations updated but so far, we've been un-successful, however, I do recommend you send a Feedback (located on the lower left-hand corner of the website).  I'll try to escalate the matter on Monday.  They also have a separate topic on this forum too so you can also help get this improved.

It's 3-in-1, so the AP1252AG-A-K9 with its three 5 ghz connections will support but one ANT5160NP-R.

That's correct.  There are two "NP-R" series and the other is for the 2.4 Ghz.  Each has three pig-tails and will work with the 1250/1260 and 3500i.

I've been unable to extract a bit of information from Cisco - their "local partner" won't return calls - the $ potential of this project is zilch, from their perspective.  I've exhausted my usual list of Übergeeks without having a more productive interaction than I've had here with you.  And finally, I note my own research has ceased churning out much in the way of new insights.

Some partners have been giving Cisco a very bad name.  Particularly if your budget does not have the letters "m" or "b" in it (if you catch my drift).  I hope that your area is served by more than one authorized Cisco reseller because that's what happened to us.  Our old supplier slaps a hefty mark-up and were very rigid because we had a contract with them.  When the contract expired, we had a "panel" and this helped us tremendously because other members of the panel were willing to bend-over-backwards to get us to purchase from them.  The difference between the old supplier and the new "panel" was approximately AU$500 or more PER UNIT.

It's area of coverage is a more-or-less ellipsoid brain blob, with the antenna displaced ≈11% from center?  (The azimuth and elevation patterns being very similar means a fairly consistent 3D shape, right?  For example, if the patterns were all circular, the coverage area would be a sphere?)  This sounds promising in terms of being able to point it downwards from the center of a roof.

I'd still install it in the ground-level.  Only the "Yagi" and/or "dish" antennae are ideal for roof-mounted.  The "NP-R" is good if you bolt it on the outside-walls and facing outwards.  Don't expect to get this right the first time around.  You'll need to test this before finally bolting it to the wall.  You can test this by "hanging" the patch antennae and with a laptop move in and around the coverage area of your requirement.  Depending on your environment this could take minutes to hours but it's the most sure-fire way of getting an accurate reading.

In that I'm unlikely to get hands-on, actual expert advice beyond what little I've gotten,  I'm feeling like I'm at the "pick your best guess and try it" stage.

Y'know how I got myself with wireless?  I am no techno-babble geek.  I'm suppose to be a pencil pusher but raised my hand to know more about wireless (because I was ignorant about it).  If you want to learn about something you need to take a first step.  And this is exactly what you've done.  You'll learn alot with this:  Mistakes and right choices/decisions.  But most importantly you know how easily to make mistakes but you'll also learn quickly from the mistakes you've made.  I am unsure if anyone shares the same feeling but "mistakes" pushes my knowledge and understanding.  And learning is an on-going process.

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Leo Laohoo Wed, 08/25/2010 - 22:49

I don't know if you've seen this document before (but it should be part of the documentation of your purchase) but if you look for your antennae, look at Elevation Plane Radiation Pattern and the Azimuth Plane Radiation Pattern.

http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html

The Azimuth Plane Radiation Pattern shows that if you hold the antennae on it's side or lie it down on your palm, the signal goes around (that's good).  However, if you hold it standing up, you'll notice the Elevation Plane Radiation Pattern shows that the signal is like a clover-leaf like.  Do you see those "pockets"?  Those are called "lobes" and it means that you won't get signal.  This type of antennae is good if you mount it nice and low or mast/post mounted.  It is not suited to be on a roof like a VHF/UHF radio.  This is not the way.

So if you are on the roof of a 3-story building, don't expect the signal to propagate all the way down to the first floor because it may not reach it.

1111eastjohn Thu, 08/26/2010 - 00:15

Thanks much - sounds like the "I just an idjit who's missing the obvious" option was right on.

That said, what do I do?  Turn the antennae on their sides?  Mount it all in the basement (the wiring closet is down there anyhow)?  Acquire other antennas?  Which ones?  The AIR-ANT5160V-R appeared to be the only antenna rated for outdoor use with the 1252AG.

No longer baffled - now merely frustrated.  This is progress.

Thanks again,

Bryan

Leo Laohoo Thu, 08/26/2010 - 15:16

sounds like the "I just an idjit who's missing the obvious" option was right on

I'm not being sympathetic or something but an id10t is a person who wrongly implements something, gets paid, moves to a different state (or change identity) and refuse to provide any support.  You are an "explorer" and a person who's willing to answer riddles.

Take the antennae down from the roof and put it, temporarily, say above the 1st floor ceiling.  Check that out first.

1111eastjohn Thu, 08/26/2010 - 23:48

Thanks for the encouragement.  If I (finally) understand the specs, the AIR-ANT5160V-R's coverage looks like this:

Assuming the 17° means what I think it means, it's a 360° swept wedge so shallow that you have to be about 33' feet from the antenna before the height of the coverage reaches 10'.  Given that the volume I'm trying to cover is a rectangular solid approximately 65' x 20' x 20' within which the antennas have to be positioned, it seems I couldn't have made a worse choice. 

Any idea what the right choice might be? 

Thanks again,

Bryan

1111eastjohn Fri, 08/27/2010 - 11:18

Interesting - I was looking at the AIR-ANT5160NP-R also.  Somewhat confusingly, it doesn't appear in the "Aironet Antennas and Accessories Reference Guide."  I found it by accident, which makes me wonder what else I might be missing.

So...

  • It's area of coverage is a more-or-less ellipsoid brain blob, with the antenna displaced ≈11% from center?  (The azimuth and elevation patterns being very similar means a fairly consistent 3D shape, right?  For example, if the patterns were all circular, the coverage area would be a sphere?)  This sounds promising in terms of being able to point it downwards from the center of a roof.

  • I'm unclear how the box is oriented within the blob, but that's no big deal until it's time to mount it.   

  • It's happy in the great outdoors - this is good.

  • It's 3-in-1, so the AP1252AG-A-K9 with its three 5 ghz connections will support but one ANT5160NP-R.

  • I'm unclear how its gain and other specs relate to its range and ability to penetrate a three-story wood frame building with a more-than-average number of interior walls.  I understand this is subject to many variables, but if you've a "more than likely" or "no way" reaction, I'd appreciate hearing it.

  • 5 ghz means 802.11n, correct?  If I want to support 802.11g, I need something to plug into the AP1252AG's three 2.4 ghz sockets, no?  The (AIR-ANT2460NP-R appears to be the 2.4 ghz equivalent.

As for "go and buy 'em" (shoppingRus)...  The somewhat-loose deadline for this project is 9/1.  I've been unable to extract a bit of information from Cisco - their "local partner" won't return calls - the $ potential of this project is zilch, from their perspective.  I've exhausted my usual list of Übergeeks without having a more productive interaction than I've had here with you.  And finally, I note my own research has ceased churning out much in the way of new insights.

In that I'm unlikely to get hands-on, actual expert advice beyond what little I've gotten,  I'm feeling like I'm at the "pick your best guess and try it" stage. 

Whaddaya think?

Thanks much, by the way, for taking an interest in my migraine-du-jour.

-Bryan

Correct Answer
Leo Laohoo Fri, 08/27/2010 - 17:21

Somewhat confusingly, it doesn't appear in the "Aironet Antennas and Accessories Reference Guide."  I found it by accident, which makes me wonder what else I might be missing.

There have been numerous requests to get the documentations updated but so far, we've been un-successful, however, I do recommend you send a Feedback (located on the lower left-hand corner of the website).  I'll try to escalate the matter on Monday.  They also have a separate topic on this forum too so you can also help get this improved.

It's 3-in-1, so the AP1252AG-A-K9 with its three 5 ghz connections will support but one ANT5160NP-R.

That's correct.  There are two "NP-R" series and the other is for the 2.4 Ghz.  Each has three pig-tails and will work with the 1250/1260 and 3500i.

I've been unable to extract a bit of information from Cisco - their "local partner" won't return calls - the $ potential of this project is zilch, from their perspective.  I've exhausted my usual list of Übergeeks without having a more productive interaction than I've had here with you.  And finally, I note my own research has ceased churning out much in the way of new insights.

Some partners have been giving Cisco a very bad name.  Particularly if your budget does not have the letters "m" or "b" in it (if you catch my drift).  I hope that your area is served by more than one authorized Cisco reseller because that's what happened to us.  Our old supplier slaps a hefty mark-up and were very rigid because we had a contract with them.  When the contract expired, we had a "panel" and this helped us tremendously because other members of the panel were willing to bend-over-backwards to get us to purchase from them.  The difference between the old supplier and the new "panel" was approximately AU$500 or more PER UNIT.

It's area of coverage is a more-or-less ellipsoid brain blob, with the antenna displaced ≈11% from center?  (The azimuth and elevation patterns being very similar means a fairly consistent 3D shape, right?  For example, if the patterns were all circular, the coverage area would be a sphere?)  This sounds promising in terms of being able to point it downwards from the center of a roof.

I'd still install it in the ground-level.  Only the "Yagi" and/or "dish" antennae are ideal for roof-mounted.  The "NP-R" is good if you bolt it on the outside-walls and facing outwards.  Don't expect to get this right the first time around.  You'll need to test this before finally bolting it to the wall.  You can test this by "hanging" the patch antennae and with a laptop move in and around the coverage area of your requirement.  Depending on your environment this could take minutes to hours but it's the most sure-fire way of getting an accurate reading.

In that I'm unlikely to get hands-on, actual expert advice beyond what little I've gotten,  I'm feeling like I'm at the "pick your best guess and try it" stage.

Y'know how I got myself with wireless?  I am no techno-babble geek.  I'm suppose to be a pencil pusher but raised my hand to know more about wireless (because I was ignorant about it).  If you want to learn about something you need to take a first step.  And this is exactly what you've done.  You'll learn alot with this:  Mistakes and right choices/decisions.  But most importantly you know how easily to make mistakes but you'll also learn quickly from the mistakes you've made.  I am unsure if anyone shares the same feeling but "mistakes" pushes my knowledge and understanding.  And learning is an on-going process.

1111eastjohn Sat, 08/28/2010 - 13:24

I appreciate your help and advice.  I'm going to spend the weekend assimilating everything I can, then order new antennas and accept that I'm going to be crawling around the roof playing.  The weather here is gorgeous, and the view of Mount Rainier, Puget Sound, and the Space Needle quite fine.

Thanks,

Bryan

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