Noise floor increased after swap to SH-TP-5-30 Horn


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Hi there,

We recently tried our first horn antenna in order to test the product in our typical environment.  We installed the SH-TP-5-30 Horn, with shielded adapter, mated to a UBNT Rocket AC Prism.  This horn replaced a UBNT 90 degree sector antenna.

The AP side of this link is in a very RF rich environment, with approximately 25 other 5 GHz APs.  There are only 2 clients associated, one at 5 km and the other at 10 km.  Both are UBNT Powerbeam AC 500 radios.  

Utilizing the same channel, mounting location and radio, the noise floor went from -96 dBm on the sector, to -84 dBm.  RX signal increased from -64 to -63.  Performance  the same.

We were very surprised and disappointed to see the SNR get worse.  Is this a typical result?  It's only our first in the environment, but it's certainly wasn't a positive start.  The marketing material set our expectations much higher.  


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Darcy - one of the common misconceptions when moving to Horns is to go and swap the old vs the new 1:1, keep original settings and expect dramatic improvement. It may and may not work. When you change the antenna, radio is now able to see different "picture of reality" through the new antenna, so to go with the same settings might not be the best strategy. Especially 90° traditional vs 30° symmetrical, those two antennas are night and day as regards their radiation patterns. So, it all depends. With the limited information we have we can not advise better, but what jober says is related. Change the settings or move the AP.

If you prefer to take the conversation offline, please shoot PM to Tasos and we can analyse in more details

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@Darcy- We will need more information about your set up to help.  As JT mentioned, its not always the best approach to automatically use the same settings. A spectrum scan should be used to identify the best channel to use as things are very different now then before with a traditional sector.

With that said, can you provide a bit more information on your equipment.  You mentioned you are using a 30deg Horn with shielded adapter for RocketAC PRISM.  We don't offer a shielded adapter for the PRISM radio so I want to verify what you have.  Do you have the box the adapter came in so I can verify the part number.  If you are using a RocketAC-LITE or RocketAC-PTP radio then it may be possible you are running and older V1 TP adapter.  That could be an issue.  Also what channel are you using?  Any screen shots of link data GPS coords, or install pics would be great.

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Thanks for the replies.  I will be firing off a PM with more details to you (coords, channel, etc).  I would appreciate your assistance, as we do like the platform and are hoping it can provide us some benefits.  To confirm, these are the two product part numbers that we ordered.  

  • SH-TP-5-30 
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Ok, So not a Rocket5AC-Prism? It's the Rock5AC-Lite, -ptp or -ptmp. (ubnt blundered the Prism name in reguards to the tech and what it's it and how. They should have said Half Prism and Full Prism.)

If you really plan to replace 90's with three 30's you need to be looking at the v2 or v1 R5AC-Prism with GPS sync.

I'm in a very noisy area and I have had the same issue with the horns. So like I said, aim it up higher or down a lot more. Remember that the 90 deg. sectors have higher gain and a 6 deg. vertical beamwidth. 

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