image showing is client device connected with mikrotik ap (R52Hn)
when i place this device in above 500 Meter distance its not connecting
i place this in 50Meter distance it connecting.i found the problem is HT chain .

RB 711-2Hn is a single chain board it have ch0 connecter only.
but in the status ch0 as RX,ch1 as TX
so the RX value is high compare to TX
so its not connecting in long distance

please tell me how to solve this problem

A couple of thoughts -

The higher you go...the more interference you're going to get.

Use the Frequency Usage and Scan tools at both heights and notice what you see - I'd imagine many more SSID's show up at 500 M than 50 Meters.

The Freq Usage and Scan tools can also help you find a "clean" channel....look at the scan list and find a channel that isn't being used. If they're all used use the Freq. Usage to find the "quietest"...it's usually a good idea to do this at peak times (evenings)....Otherwise you might find it works during the day and dies a night

Regarding the 0 values...from my experience, unless you have mikrotik on both sides you're not always going to get accurate readings from the other end of the link.

Also - Why do you have the board in "B" Mode? Is the AP only B?

this is not height problem its a HT chain problem

Your RB711 is evidently damaged. Read this topics:
http://forum.mikrotik.com/viewtopic.php?f=3&t=59203
http://forum.mikrotik.com/viewtopic.php?f=3&t=56747

this is not height problem its a HT chain problem

More specifically, you should have chain0 enabled for both Tx and Rx, and chain1 disabled for both.