Hi,

Quite, a uhm... Unique situation I think... I had a look at some calculators on the net, and yeah... I can't believe their answers in saying I need more than 130dBi....

The situation, is that I need to cover a 41.2km (Let's work with 42km) point-to-point link (with full LOS - over the ocean ). Obviously, I will be using directional antennaes, and the biggest I found so far are from YDI Wireless, operating at 23.5dBi with a 10 degree beam width at 2.4GHz (which may be a issue as well based on the distance).

So I guess, my question would be as follows....
Will 5.8GHz operate better than 2.4GHz on this link, and well yeah, what exactly is required antennae, amp, AP, etc wise to get this link to operate. Obviously, I require as much bandwidth as possible. I'm tempted to actually try and operate on at least a 43Mbps pipe... The alternative I presume would be just to simply go and install a full on Microwave link?

Look forward to your interesting ideas and suggestions

PS - I can get 39.8dBi Directionals (operating at about 1.6 degrees beamwidth) for 5GHz from YDI as well... I presume the extra 10+ dBi would make a significant change to the equasion.....

Ok, I have link between to cities and the distance is 27km, my signal is perfect and ping between them is 3ms. It is on 5.2GHz atheros 2511 and satellite dish is 1.3m with 5ghz feed, other side is the same. We have a big traffic like 1mbit/s average and people are playing games online etc. If you want to do serious don't us B/G use 802.11a.
Cheers...

Some people here have reported links up to 50 km in .11a.

I was using a 5ghz link (Tranzeo) over a semi-salt water river about 1/2 mile wide and had polarization problems due to reflections. We had to use horizontal to make it work correctly. You may want to check on polarization over water issues if your link will be that far over water.

I believe the biggest issue is the salt water area. A while ago, I was unsucessful to get a 15km link, where all other conditions seemed perfect. Maybe indeed horizontal polarization is the answer (but then, wouldn't that exibit more reflections form the surface?)

Daniel

I would like to set up 3 links between 2 big buildings in a city, complete LOS (a lot higher then other buildings), distance is about 3 km and need at least 40 Mb/s.

I am pretty used with MK (traffic shaping and firewalling but not wireless)

I suppose the solution goes through having a PCI card installed on the routerboards, using 11a and a big antenna, but I would like to have some more detailed info:

- which card to mount on the routerboard ? where to buy it or which supplier ?
- is routerboard enough to have a link like this?
- which antenna is reccomended ?

- which card to mount on the routerboard ? where to buy it or which supplier ?
miniPCI 802.11a/g suits fine

Have a look at:
http://www.mikrotik.com/interfaces.php#linx1
http://www.mikrotik.com/antennas.php

Contact sales@mikrotik.com for more information.

- is routerboard enough to have a link like this?
yes

- which antenna is reccomended ?
High gain directional