working on an STM-1 link at 155 mbps. Distance is sub 3 kms however the radios are oprating at 38 ghz. 0.6m antennae with gain of aprox 45 dBi max power out of 16.5 dBm. and BER 10-6 at -63 dBm on RX. Link budget looks good with RSL of about -29 dBm, however we are having trouble predicting rain fade. Its in the ptropics. Anyone got a simple rain fade calculator which gives atenuation in dB given path lenger operating frequency and rain density in mm/hr?