[amsat-bb] Re: 2 ghz antenna question

[k0vty@juno.com]

Hi Chris

I have had a 15 mile one way , 2 gHz, 3 foot, 100 mw, RF link for 
my ISP for 7 years now, and it has never given me a problem.
A 50 foot run of LMR 400 is used here.
My grid dish has 23 dbi gain.
A Cisco model 350 is in my computer.
I will assume for the moment my experiences somehow fit your situation
and might be useful to you.
I use a telescoping Radio Shack mast to mount a vertically polarized 
Grid dish.
The mast is mounted on a lower roof level , using an upper roof peak
bracket to stabilize the mast.
It is a good solid mounting.
The antenna is looking down a water shed that falls away at 3 foot per
mile.
That clear all the trees.
Trees are a real bad attn on 2.4 gHz
The grid  dish is mounted vertically ( dish rods in the vertical plane)
because the ISP uses that polarization.
If I were to consider using two dishes I would test two dishes side by
side.
Diversity reception ( using two receivers ) of two stacked vertically
might cancel some signal when mama nature does her tricks.
Where as what ever trick mama nature has in store should remain the same
for two antennas side by side.
The effective aperture of a dish is the physical size of the dish so
the distance between is not as critical.
Where as the above and below mounting has to do with how mama moves the
signal vertically over time.

I hope this has provided some food for thought

Joe  K0VTY
==================
On Wed, 08 Aug 2007 16:56:02 -0700 Chris Huber <cahuber at ucdavis.edu>
writes:
> Hello,
> 
> I know this is off subject, I am looking for ideas on stacking 2 
> antennas.
> I am doing a 25 mile WiFi link on 2 GHz using 1  3 foot grid dish 
> with 
> horizontal polarity. I have a power divider and a second dish that I 
> 
> want to mount directly above the first antenna.
> 
> Is the vertical spacing critical?  Is there any advantage over close 
> 
> spacing,  ie. increase gain or wide spacing to give better path fade 
> 
> protection.
> 
> Thanks for your time.
> 
> Chris N6ICW
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