15KM LINK PTP which antena+radio do you recommend

hello I Want to create a link to transmit 80/80 Mbps of data. but i dont know which antenna to choose.

the problem is that in the first tower i have problems with 5Ghz band becouse there are 100 other antennas there and i have a lot of interfernce.

i tried with RF elements antenna 32dbi grid with pair of Metal 5SHPn in bridge mode

maximal throughtput is about 50/40 mbps

any idea ?

You get 40/50Mbps MAX in UDP testing or in TCP testing method?
At what Mbps are you locked at and what is your signal, Tx/Rx CCQ?

You can try MIMO http://en.jirous.com/antenna-5ghz/jrc-29ex_mimo
and rb711GA or rb911G

I second honzam, pretty impressed until now with Jirous antennas.