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Advice and suggestions

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k3la
Advice and suggestions
We are planning to replace two nodes on a local tower that have been up for maybe 4 years. They are Ubiquiti bullets with omnidirectional antennas. One on 2.4 and one on 5ghz. We would like to replace with something and the question is what. We have not built up a AREDN network in the area but have been trying to get activity in the area. Cost per say is not an issue but reliability is since they are not readily accessible. We are planning on tower work this summer so it will be easy to replace what is there now.


Any thoughts or suggestions would be welcome.
Barney K3LA
 
k1ky
k1ky's picture
Advice and suggestions

Highly suggest that you go with something dual polarity.  Are you getting any activity with your current setup?  Maybe something with sector antennas, either UBNT Rocket of Mikrotik Basebox and Sector antenna(s).  Do you have any particular areas that you wish to have coverage?  Unless you are mounted on "top" of a tower, the Omni isn't probably going to do much for you due to tower shading off the back side.  Concentrate on 5GHz, 2.4GHz around here is almost totally useless anymore due to overload and congestion issues.

k3la
Advice and suggestion
Actually limited activity. We had a push last summer to start some ue but it dropped but may start back up. They will be an the top of the tower. At this point no particular direction. Locally people have purchased  2.4 equipment so I want to include that. I have gathered that dual polarity is better. Do you have any specific suggestions? We may add sector antennas as we start to built up usage. Thanks Barney K3LA
k1ky
k1ky's picture
Advice and suggestion
Well, depending on how many "users" have 2.4 GHz gear out there, I would start over with Rocket/Basebox 5GHz Sectors Miktotik also makes some other integrated units with antennas what we are evaluating.  Another problem with Omni antennas especially high up on towers is that you don't have any control over downtilt,  Rather repurpose those units for local deployment say at a staging area or Field Day site.  
k3la
Advice and suggestion
Several stupid questions What is the minimal number of sector units to cover 360? Should or must you run separate lines to each sector unit? Barney
k1ky
k1ky's picture
Advice and suggestion
Minimally you would need three (3) nodes with 120 degree sector antennas.  Separate ethernet lines to each, which gives you redundancy in case of single line failure.  There are some switch/POE tower mounted distribution devices available, but then you introduce another single point of failure.  Good quality Ethernet cable for tower outdoor use is relatively inexpensive as compared to what we spend on heliax for repeaters!  We have been using Ubiquity Tough Cable Carrier.  You can spend more for the higher grade "gel filled" cables.
nc8q
nc8q's picture
What is the minimal number of sector units to cover 360?
Hi, Barney:

Do you really need 360 degree coverage?
Would 1 or 2 or 3 'panel' devices do as well (each 60 degree coverage and << $)?

73, Chuck
 
k1ky
k1ky's picture
UBNT Omni
Then probably a UBNT Rocket and their biggest 2.4 GHz Dual Polarity Omni antenna may be the way to go if you can't get everyone focused within a 120 degree sector. 
w6bi
w6bi's picture
Sectors

Ubiquiti and Mikrotik report their beamwidths at -6 dB (1/4 power) rather than the traditional -3 dB point.  So users on the fringes of the coverage may not get as good of a link as they might expect.  Our rule of thumb here is to overlap sector antennas by at least 20 degrees to avoid that zone of reduce coverage.  While that means if you need 360 degree coverage, four sectors would be needed (that would be 30 degrees overlap).   For many high level installations, users are usually bunched together (in communities, etc), meaning 360 degree coverage isn't really needed.   As they say, your mileage may vary!
Orv W6BI
 

KV3T
KV3T's picture
Barney,
Barney,
I just wrote a proposal for a similar site.  Send me an email and I'll email you back the proposal.  It will show you what I propose for a 120deg sector.  Very similar to what was suggested above, but like 40 pages of detail in my proposal to the site owner (a municipality) and the sponsor agency (a ham radio club).  It includes extensive RF modeling and details on the backhaul link and expected connection quality.  That proposal is for a point to point back haul link and a single 120deg sector.  You could add additional sectors to make it a 360deg coverage site.  We are hoping to build out this water tower site this summer, pending approval at a board meeting in two weeks.  Feel free to steal anything from that proposal.

My email address is good on qrz.

I'm happy to share with anyone else that would like it, but there are some details on it that I'd prefer to not post publicly.  I write construction specifications for a living, so it is an area I have some experience in.

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