I tried a CPE with an antenna of 22dbi and a RB711 or RB411+R52. I have good signal with the RB411+R52 (-70db RX, -72 TX) while with the RB711 I have a signal of -70db RX and -81 TX, same BTS, same position. The BTS is a RB433ah with an ubiquity XR5. The problem seems to be in the power of the RB711 (23dbm) when it works in 802.11a.