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13 mile backbone, questions

Posted: Tue Feb 12, 2008 7:05 am
by 0ldman
I'm starting up soon, within the next couple of weeks. I've got a 6.6 mile shot to my tower, planning on a 29dBi 5.8GHz grid on each end and R52s. From there, I'll have a 29dBi 5.8 going 3 miles to a tower with 2 ft size limitations, so I can only use a 26dBi. This is the part I question.

From there, the plan is a 26dBi/R52 5.8GHz shot 13 miles, open space, perfect line of site and fresnel is clean, with a 29dBi/R52 on the other end. Is the 26dBi antenna going to be enough for this distance?

Online calculators show it works fine, however they have been overly optimistic with my other p2p shots. I don' t see any reason it wouldn't work, but the longest shot I have experience with is 5 miles. I just wanted to ask those that have done it before I get money tied up.

Re: 13 mile backbone, questions

Posted: Wed Feb 13, 2008 5:21 am
by Aug
I'd say it would be unreliable at that distance.
You can get a 29dbi solid dish that is 2 foot and a 32dbi is 3 foot.
If you're running 3' of lmr400 you should have a good link with about a 11 db fade margin.
Aug

Re: 13 mile backbone, questions

Posted: Wed Feb 13, 2008 6:03 am
by kthameen
You should hit the 25 mile with a clear channel and an exact alignment and I emphasize on alignment

Re: 13 mile backbone, questions

Posted: Wed Feb 13, 2008 11:41 am
by Tanker
We run several 50 mile ptp links using R52H and 27 dBi Grid Antennas
These work very well and have been up since day 1 (278 days now)....

Yes alignment is critical - but you'll soon get the hang of it...

These are the grids we use: -

Freq. Range-MHz 5725~5850
Gain -dBi 27
Horizontal Beamwidth 6
Vertical Beamwidth 9

F/B Ratio dB ≥25
VSWR ≤1.5
Input Impedance-Ω 50
Polarization Vertical or Horizontal
Max Power -W 100
Connector N-Type Female
Dimension-m 0.4x0.6
Weight kg 2.4


Hope this helps

T

Re: 13 mile backbone, questions

Posted: Wed Feb 13, 2008 9:55 pm
by nexus010
Yes I'll add to this that your link budget is more that adaquate.
I have shot a 5.8Ghz 28km link with 2 27dbi dish's and 2 100mw cards.
There was more than enough signal , 48 mb connection rate, although throughput was poor.
I have since divided the link in 2 and more than doubled the throughput.
On one end of each link I have an original 27dbi grid on the other end only a 17 dbi flat panel ant.
Each of these links is +16 km ! (the divided original shot takes a differnt path)

Throughput and reliability have been rock solid over 2 years now.
They connect at 108 mb "turbo" without fail
In storm conditions it slows down to 96 mb never lower.
The larger dish not only improves transmissin strength but reception sensitivity.
I have been able to connect and surf off a 24 dbi ant on a 24m tower in 2.4ghz with a 18mw laptop card with no external ant at over 6km ! again the the dishes sensitvity is the key.


I have found this calculater indespensible http://www.terabeam.com/support/calculations/som.php
Have fun with your link !

Re: 13 mile backbone, questions

Posted: Wed Feb 13, 2008 10:11 pm
by nexus010
Yes I'll add to this that your link budget is more that adaquate.
I have shot a 5.8Ghz 18mile link with 2 27dbi dish's and 2 100mw cards.
There was more than enough signal , 48 mb connection rate, although throughput was poor because of long ack.
I have since divided the link in 2 and more than doubled the throughput.
On one end of each link I have an original 27dbi grid on the other end only a 17 dbi flat panel ant.
Each of these links is +10 mile ! (the divided original shot takes a differnt path)

Throughput and reliability have been rock solid over 2 years now.
They connect at 108 mb "turbo" without fail
In storm conditions it slows down to 96 mb never lower.
The larger dish not only improves transmissin strength but reception sensitivity.
I have been able to connect and surf off a 24 dbi ant on a 60foot tower in 2.4ghz with a 18mw laptop card with no external ant at over 4 miles ! Again the the dishes sensitvity is the key.


I have found this calculater indespensible http://www.terabeam.com/support/calculations/som.php
Have fun with your link !

Re: 13 mile backbone, questions

Posted: Thu Feb 14, 2008 12:14 am
by chvdr
go ahead, it will be okay

Re: 13 mile backbone, questions

Posted: Thu Feb 14, 2008 1:36 am
by 0ldman
Thanks for the input guys, the yays and the nays. I think I'll probably swap the R52 for XR5 for the long shot just for headroom. The extra power might make it easier when we start alignment.

http://www.zytrax.com/tech/wireless/calc.htm

This is the calculator I've been using, it doesn't require a page reload for an answer.

Re: 13 mile backbone, questions

Posted: Thu Feb 28, 2008 10:49 pm
by nickb
You can get much more precise information by using some link modeling software, that will actually take topography in to account - I use Radio Mobile, which is free, flexable, and highly useful.

Re: 13 mile backbone, questions

Posted: Fri Feb 29, 2008 5:14 pm
by jordantrx
You can get much more precise information by using some link modeling software, that will actually take topography in to account - I use Radio Mobile, which is free, flexable, and highly useful.
I use radio mobile aswell works very nicely i may add! thanks Sid for setting it up for me! -Jordan

Re: 13 mile backbone, questions

Posted: Fri Feb 29, 2008 6:50 pm
by 0ldman
I'm going to try it soon, if the phone will ever quit ringing...