Sergio;
Here are some things to consider;
1. You have a path loss of 110 dB at 2.4 GHZ.
2. Your system gain is 94 dB (+14 dBm Tx PO, -80 dBm RX sens)
3. You need at least 16 dB antena gain to make up that difference, you
would be very lucky to have that kind of gain with two 7 element
antennas. Two tens might just make it. You should consider a dish
antenna.
Other considerations:
4. Is the path unobstructed? Any obstacle near the path could cause a
reflection.
5. Does the link work properly when all the equipment is within a
reasonable distance, say 100 feet? To preclude problems unrelated to the
path.
6. What type of transmission line and what is the length of thea cables?
I assume you are using proper RF connectors?
7. Power lines should not be a problem especially with vertical
polarization.
8. Antennas should be boresighted to each other. A small laser can be
helpful to orient the antenna's, do this at night. Be careful not to
blind your helper.
Sergio Depres wrote:
>
> Hello, everybody, I'm glad of finding this list. Here it is my problem:
>
> We are installing an outdoor wireless datalink (2 miles), we have
> confirmation that our 2 antennas have different heights.
>
> Building1: Height of the building - 48 feet. Mast -> 18 feet Total -> 66
> feet
> Building2: Height of the building - 39 feet. Mast -> 27 feet Total -> 66
> feet
>
> The thing is that the First building's roof is almost at the same level
> that the roof in the building two, so in fact our antennas have a
> vertical disalignment of about
> 9 feet.
>
> We are using right now vertical polarization, and our performance is
> very poor.
>
> Question1: For the 2.4GHz band, using vertical polarization, 7-10
> elements Yagi antenna, what could be the allowed disaligment on the
> vertical axis?
>
> Question2: We have seen a couple of high voltage cables that are inside
> the propagation path, what could be the best polarization for avoiding
> them.
>
> Question3. Does anybody know if there is any site license required for
> outdoor applications of 2.4GHz wireless datalinks?
>
> Here is more data if somebody needs them to understand better what I'm
> saying.
>
> Distance between linked offices: 2 miles.
>
> Antenna: 2.4GHz Yagi Antenna manufactured by TTI Wireless.
> As far as I remember there are about 7 to 10 elements.
>
> RF specs:
> Modulation: Spread Spectrum- DQPSK
> Output Power:14dBm
> Receiver sensitivity:-80dBm
>
> --
> Sergio G. Depres, IS Responsible
> Atlas Paper Mills
> 3725 East 10th Court Hialeah, FL 33013 USA
> Phone: 305-835-8046 Fax 305-691-6018
>
> --
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--
Joe Leikhim K4SAT (EX KE4TZH)
Jleikhim@nettally.com
"tv dinner by the pool,
i'm so glad i finished school" -F.Zappa 1967
"The Revolution will NOT be televised" -Gil Scott Heron
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