Hi to all!
I will evaluate to make a link of about 80 km, oversea.
Site A elevation: 100 m
Site B elevation: 500 m
I need about 100 MBit real TCP througput… it’s possible with Mikrotik board?
I think your post is a question!
With over 30 years in Radio Comms, my honest answer will be " I doubt that it is possible"
In theory and with many programs to determine link loss, they will say that it is possibele.
For example, and just a guess, I expect 2 x 32 dbi parabolic dishes and Ubiquity XR5 will get you somewhere.
But in practice, the sites are too low and you will suffer considerably with ducting (atmospheric conditions).
It is extremely difficult to model a link across water at these altititudes, on a fine day it could work, on another day no.
My gut feeling is that your sites are far too low, and you will have problems with:
a: Refraction
b:Ducting.
c: Multipath issues.
d: the earths curvature.
There is another post on the forum with someone who is also trying a sea path link at similar altitudes and he has problems. I am following his post with interest.
Regards
Simon
Tnx!
Very exaustive comment.
Yes, my post is a question 
And… I can consider a PDH/SDH link or I will have same problems?
its not possible 100 mb link 
Max reasonable througput?
Using n-stream dual, or any kind of aggregation…
I used to install commercial radio links, you know from studio to transmission site, yes many of these were SDH links.. But those links were just a few kilometres.
Microwaves suffer more from defraction than at any other frequency.
The distance is just to great and the site levels way too low.
Those guys that have done 304km links, which yes I agree have a sea path, have sites that are so high at each end that they can no longer be considered “tru sea paths”.. Those links can more or less be modeled by “free space” design. Taken nothing more into account than pure “free space path loss”
Your proposed link is so different.
Sea temperature, air temperature, dew point etc are factors of huge importance… Not only that, but without refering to a “path calculator”, the distance is too great and you will surely be affected by the earths curvature.
It may be possible to get the link to work, but as someone else experienced similar issues in the forum, it was up more days than it was down.. In fact I believe his link was say 85% uptime, and the poor chap was pulling out his hair looking for reasons why he was loosing 20dB of signal on some days..
Until I said to him, to turn the problem upside down, in so far as, it is quite likely that on the days that the link was working, it is likely that the signal was being enhanced, and that on the days that he lost 20dB.., these were the normal days.. ie days without enhancement.
Hope that helps.
Simon
tnx
Distances are from “path calculator”. 
I will try other solution…
@ magnavox: What happened w/ the project? Any success?
Regards
Ralph