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miahac
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sextant poor antenna 0 for 2

Fri May 18, 2012 5:20 pm

I have tried 2x to install Sextants ad different locations with no success.

This is on a working network: The ap's (4 RB RB711GA-5HnD with ubiquty 90 degree 5g sectors) on a 20 floor office building. I can connect fine with -50 to -55 on all chains(130mb, 20mhz, n only nv2) with SXT from pretty much any of the office buildings 1-5 blocks a way (1km max).

First. I go 3km west visual LOS but some possible obstructions in the Fresnel to the NW antenna, to a 2 story roof top and put a Sextant, chain 0 -65T/-85R, chain 1 -71T/-72R. Not good but I have had this type of connection work before, some speed tests look ok, then I see quality is 13%. This was 2 weeks ago, we had plans to add another AP that is on the corner of the building that would have no obstructions in Fresnel so I put it off (and have not been back yet).

Second. I go to a second location, 3km north PERFECT visual LOS, I can see the top 15 floors of the building. I can see the AP's with binoculars. Another sextant, almost the exact same results. We were almost done with the new AP, so I wait 1 day, point the center of the sector right at this site, try 3-4 different channels in the 5.1-5.3 and 5.7-5.8. In no case could I get all 4 signals better than -80, and no signals better than -70.

I then decided to look up the antenna pattern of the sextant and discovered it 5.3-5.6ghz bias which we have no use for in the USA, and it is as low as 12.5db in useful frequencies.

It should be noted that I do have a -65 11km straight north using a 411/r5n and 24dbi dual pole arc wireless ism antenna connected to the same NW antenna. I guess I will order a couple of these antennas, that cost more than the whole sextant.

I have decided that I will only use sextant for p2p under 2km due to these problems.

Please come out with an octant or some other funny name that has a good 24db dual pole antenna.
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CyB3RMX
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Re: sextant poor antenna 0 for 2

Fri May 18, 2012 9:39 pm

I just bought 38 of them...

i'm going to install the first Sextant P2P on monday.. 6 Km. i let you know my results.

Greetings.
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normis
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Re: sextant poor antenna 0 for 2

Mon May 21, 2012 9:11 am

What are "useful" frequencies for you? http://routerboard.com/pdf/364/sextant.pdf

Below 5GHz? as within that range, I don't see 12.5dBi like you say
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miahac
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Re: sextant poor antenna 0 for 2

Tue May 22, 2012 4:52 pm

Checking the chart again, I see its not at 12.5db at those frequencies but the sweet spot for this antenna is in 5.4-5.6 which is not useful to US. But in practice, I cannot explain why a 3km clear link will not work to my needs.

Cant get my hands on an arc I will try again on Wednesday with an Poynting antenna and 711.
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saintofinternet
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Re: sextant poor antenna 0 for 2

Tue Oct 16, 2012 8:25 am

I just bought 38 of them...

i'm going to install the first Sextant P2P on monday.. 6 Km. i let you know my results.

Greetings.

what were your results with the 6km link using sextant??
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saintofinternet
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Re: sextant poor antenna 0 for 2

Sat Jul 13, 2013 8:33 am

any update on the results??
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WirelessRudy
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Re: sextant poor antenna 0 for 2

Mon Jul 22, 2013 12:15 pm

any update on the results??
He probably found the issue was in the ubnt antenna's. Not in the SXT's.

I use SXT's up 7km distances. They are surprisingly good for such low gain antenna's.
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saintofinternet
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Re: sextant poor antenna 0 for 2

Mon Jul 22, 2013 5:56 pm

are you having a clean line of sight??

and please mention the exact SXT model... with so many launched now :)
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Re: sextant poor antenna 0 for 2

Mon Jul 22, 2013 6:06 pm

I use all kind of SXT models. Mostly the new 5Ghz lite versions thow but before the normal ones.
At short distances, up to 1km NLOS is supricingly good. Got one with at least one story of a building inbetween blocking direct line of sight and client is still connected.

Be aware thow, in this case the AP works with 40Mhz bandwidth and NV2 and the client is only allowed to have 3Mb of traffic. So this gives plenty of marging for the CPE to work with. Signals are in the -70 range and CCQ is 60-80 range and fluctuates. A LOS would be much better but ok, this client is served.....

I have one AP that actually uses 30dBi duo chain dome and it is serving SXT's at a distance of 10 to 15km's. Signals are in the -70 to -55 range and good CCQ's.
To reach corners of your working area this is a good solution.
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Re: sextant poor antenna 0 for 2

Mon Jul 22, 2013 6:08 pm

By the way, tread was about Sextant. We talk SXT now.
Sextant is only doing slightly better, but cost twice as much.....

Main disadvantage of both series: Lack of shielding against unwanted signals on other bands or from other than the desired directions. (Creates 'noise' or interferences)
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Re: sextant poor antenna 0 for 2

Tue Jul 23, 2013 2:09 am

That's why I use aluminium tape...
 
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Re: sextant poor antenna 0 for 2

Tue Jul 23, 2013 2:37 am

Or use a paintspray that contains metal particles. A zink containing spray like workshops use to protect welded parts in galvanised contructions works good for me.
I spray the back and sides of the housing with 2 to 3 layers and once made a test that signals were indeed dropped by 3 to even 6dBs!
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saintofinternet
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Re: sextant poor antenna 0 for 2

Tue Jul 23, 2013 4:13 am

Or use a paintspray that contains metal particles. A zink containing spray like workshops use to protect welded parts in galvanised contructions works good for me.
I spray the back and sides of the housing with 2 to 3 layers and once made a test that signals were indeed dropped by 3 to even 6dBs!
can you post some photos for guidance... please...
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