in modern point to microwave systems, unless the budget is really high, or the path is very long, it's rather unusual to have a vertical spatial diversity setup. much of the problem of losing link due to fade is accommodated by modern radios that have advanced variable modulation and FEC, which can operate anywhere between 4096QAM 5/6 and QPSK 1/2.
Interesting, thanks. My information is dated, but also it was a project with some specific requirements. It's possible that our client opted for the vertical spatial diversity setup because of that.
I'd be interested to know what you think is a very long link ... 10km? 100km? I can't say too much more about where we were.
Beyond 35-40 km is where you would start to see atmospheric ducting, temperature inversions and such really affect a link. In the bands where it pretty much has to be 6 GHz because anything 11 GHz or above (in the FCC licensed bands) would suffer extreme rain fade with the rain rate and amount of rain in the total length of the path.
Generally things where you'd be looking at a pair of 6 ft high performance dual polarity dishes at minimum, and ideally a pair of 8 ft. The budget for just a couple of those and getting them properly mounted and aligned is a lot already before adding a spatial diversity second dish at each end.
We were mostly dealing with 5km to 10km links, and it was some time ago. There were other considerations as well, so I didn't get into it too much ... not my field, the peeps doing the work seemed to know what they were doing (both customer and supplier), and I had other things to worry about. Extreme real-time data compression is interesting when you're on a lossy link.
I don't think budget was a problem for this customer, getting it right was important, but useful to know about the options and constraints ... thank you.
