Hi all,
I need to establish a 90 km link from baghdad GPS: 33 19’57 N 44 24’15 E- karbela GPS: 32 37’00 N 44 01’50 E ( Used Google Earth to get GPS Locations ) the area is flat no mountins and no hills, but the Earth is round, want to use the 5Ghz band.
I want to hear your suggestions on how to the link, how to calculate the tower lengths, from where to get the 1.2 - 3 meter dishes, all things that you can help me with i would appreciate it
Thanx
For LOS and FRESNEL, you need 160 Mts in both sides (Towers)…
This is the earth curvature between the points… A simulation with 160 mts of tower in both sides…
Regards 
This is link is very much acheivable provided you meet the fresnel info. typed above.
You can use two 32.5dbi dishes on both ends (1Metre) backed by xr5’s.
expected rssi: ~-56-57
Fade margin: 30db
Fresnel Radius: 115.8ft - for 5.8
Curvature imposed by the earth: 450ft
Required Antenna Height: 565.8ft
With the above you can easily achieve a 54 meg connection, possibly turbo. But its best to use Nstreme.
Regards
hi again
i would like to mention that baghdad and karbala are almost on the same hieght above water surface baghdad 34 m and karbala 30 m
the distance between them 90 km
dont u think that this is very high tower 160 m ???
is these measures perfect no way to make it smaller ??? 
One could be really believe that the earth is flat 
No, you need to get up to compensate for earth curve…
/Henrik
In the graffic, you can see the REAL curvature and imperfections between the points that you want to link…
This graffic is not a prediction… , it´s real…
The Pink LINE is Fresnel for 5.7 Ghz…
Regards
chipi, what did you use to model that?
or is there an easy earth curvature calcuation so i can figure out how high towers need to be, given a distance
Well… can you let me know which wireless calculator you used. because i tried a few online calculator and every one had different result than those posted by you
Trango has a pretty decent and simple link budget calculator.
Should suffice for what you need, if not you can try radio mobile for a more advanced approach.
http://www.trangobroadband.com/infobase/downloads/TrangoLinkBudgetCalc.zip
Regards
very nice tool.
thanks,
one question, for say a 16 mile link, it shows a required antenna height of 93.92ft. I"m assuming this means both antennas need to be at 93 feet or greater.
how does it work if you have one antenna at 250ft, can the other be lower since you will be pointing up, thus less earth curvature effect?
thanks
Well you answered your first question… (both ends must be at the indicated height) – This is so because the program takes into account the fresnel zone of the “inputted” freq. Secondly, yes you can essentially “less” the earths bulge effect with height of course. As in the case of the 250ft mark, the lowest you will be able to place the rx antenna is at 10m (~33ft) in order to have a clear rf zone.
If you double the tx antenna’s height you can overcome the fresnel zone by keeping the rx antenna’s height at least 39% of the initial “leveled” height required assuming both points are at sea level.
Regards.
Hi Chipi
Plz what software did you use to get this schema??
is it free???
There is any free softwares that can i use to get simulation of the link like this schema??
Thx
My company is an Authorized Canopy Solution Provider (ACSP), so we have Motorola Link Estimator Soft… I don´t know if it´s free or not…
Suggest : Google : Motorola Link Estimator 
The graphics are EXACTS, give me to Points with rivers, or mountains in the middle.. and you can see …
Regards
I can say that the software is free . I have downloaded it and made some sampe layouts.
Thanks Chipi for thr Goodie
Radio Mobile Deluxe Is excellent software for modeling long range links like this. I highly suggest using it, though the learning curve is a little sharp, once you figure it out it is quite useful.