[NLRS] 24 ghz EN04RB 2nd Attempt

[Dr. Gerald N. Johnson, electrical engineer]

RH is Relative Humidity, the percentage of moisture compared to air
saturated at the dry bulb temperature. RH wanders all over, generally
from high in the morning, to lowest at mid afternoon, while unless there
is a large air mass in motion or a crop with very wet feet is trying to
dry the soil with evapotranspiration, the dew point (temperature at
which the air is saturated) stays relatively constant over the day. Some
automated weather stations, especially the AWOS supported by the FAA,
not NOAA, have bad dew point sensors that often show a 20 degree F
diurnal change when the manned stations show only 1 degree F diurnal
change. This happened last summer at Carrol and Denisson Iowa showing
large diurnal changes in dew point with virtually zero wind speed while
Omaha and Des Moines ASOS stations showed virtually zero changes in dew
point. So the AWOS stations show record high heat indices while the good
stations were perfectly normal and not far away.

Give any two of the three values, RH, dry bulb temperature, and dewpoint
temperature, it is possible to compute the other. Takes a couple dozen
lines of code in C or Java. Good formulae may be found in various
editions of the ASHRAE fundamentals handbooks.

For the multiband microwave station, a fly swatter flat reflector on top
of the rotating tower with a shelf for feeds near the bottom may be a
handy scheme to get to clear houses. There's room for a bit of
adjustable tile on the fly swatter to try to find the optimum departure
elevation angle, which for the very directive antenna typical of
microwave long range hamming may not always be at the horizon.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.