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 Subject :Side mounted node on Rohn 45.. 2014-04-23- 04:27:12 
KM2O
Member
Joined: 2012-09-22- 11:04:45
Posts: 25
Location: Albany NY

All,

We have the possible opportunity to get our area's first truly wide area node installed. The site is well above average terrain of the metro area with good line of sight.  The node, as envisioned, will be a Chinese made 18dbi (although I rather think that is an optimistic measurement) whip fed from a Ubiquity Bullet M2 HP fed by outdoor rated CAT 5.  All well and good so far. The rub is that we cannot get placed at the top of the Rohn 45 tower now offered.  The owner is fine with a side mount which raises some questions.  

How far out from the tower should we place the whip?

There will be pattern distortion no matter what I fear, but has anyone done a similar install and give guidance?

Anything we might be missing?

Thanks in advance!

Dave KM2O


 

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 Subject :Re:Side mounted node on Rohn 45.. 2014-04-23- 04:53:11 
KG6JEI
Member
Joined: 2013-12-02- 19:52:05
Posts: 516
Location

Well, the wavelength on 2.4ghz is a very short distance (12cm) so going out does not have to be very far to avoid distortion of the RF field.

The bigger item is actually the shielding the tower will add. 

Consider anything that would go through the tower itself as if it is 100% shielded and that you will not be able to make contact. Some signals may get through because of the gap in a room tower but I would advise considering anything in that direction as a NULL for planning purposes.(I tend to plan pessimistically on RF out of habit to increase my margins )

The further out you go the less degrees potentially nulled out by the tower.


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 Subject :Re:Side mounted node on Rohn 45.. 2014-04-23- 06:51:48 
KM2O
Member
Joined: 2012-09-22- 11:04:45
Posts: 25
Location: Albany NY
Thanks for the fast reply Conrad. I had surmised that might be the case although I was hoping that the short wavelength would mitigate it somewhat. Based on that we should mount on the face toward the most population and hope for the best off the sides. 18 inches out is already 4 wavelengths so a longer sidearm might just give us 270 degrees or better. Thanks again.
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 Subject :Re:Side mounted node on Rohn 45.. 2014-04-24- 01:31:46 
KA0IES
Member
Joined: 2014-04-23- 06:06:27
Posts: 1
Location
Here is an idea for helping fill in the holes of the coverage from this site. Put two nodes on the tower. One on one side and the other on another side. To help reduce coupling in the antennas have one placed above the other. Maybe place them such that they can both see the most populated area from opposite sides of the tower.
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