Does anybody knows what might be the problem! Two 532 RBoards with Atheros 5213 cards in low distance scan each other but at 3 km distance not! I have changed cables antennas - the same problem! Only when I changed value in scan list from default to default,5220 that I am scanning in that frequency I could scan my access point 
. Signal quality also was bad -85DB !!!. In 2,4 GHz no problems! I have worked before with routerboards without any problems. Maybe latest versions of MT software or Atheros cards have serious bugs 
? Please somebody help!
In this area I am the only one who uses 5 GHz frequency. There are not other ISP.
What antennas are you using? Hopefully not the same as the 2.4GHz ones.. 
Regards
HP
No, only real 5 GHz parabolic antenas 30DBi!