Paul, W9AC said: <As I recall, HFTA software has an ionospheric module that
calculates the
predictability of arrival angle as a function of frequency, time of day,
season, etc. Learning that program has been on my "to do" list for a long
time. Perhaps others here can comment on whether the arrival angle
information goes down to 160m in that program.
N6BV's HFTA software does include arrival angle statistics for 160M, but I am
not sure of how useful this data is for Topband in the real world. The
propagation statistics are cumulative over all conditions, times of day and
seasons and do not allow one to specify a time, season, or solar flux. Also,
HFTA only analyzes horizontally polarized antennas and does not do vertical
polarization, which also limits the usefulness on 160M. My terrain is
extremely rugged, with steep ground slopes on all sides of my towers. I used
HFTA extensively before building my first tower. It caused me to alter my
plans for stacking two C31XR yagis, with the top one planned for 100', because
the software predicted the top antenna would destroy the pattern. I ended up
going with one C31XR at 56', and even then HFTA predicted 15 and 10M
performance would be compromised because the antenna was too high for some
directions on my hilltop. I went ahead with the altered plan and sold the
unused C
31XR but spent the next two years proving to myself the HFTA prediction about
15 and 10M was accurate. The proof involved erecting two other towers and
installing lower 10 and 15 meter antennas with equivalent gain to the C31XR and
doing extensive A versus B testing. Without exception, if HFTA predicted that
30' a high antenna in a given direction would outperform an equivalent antenna
at 56', the prediction proved true. This usually manifested as absolute higher
signal strength in A versus B tests. Sometimes in a given direction HFTA
predicted the higher antenna would be best, and this was always true as
predicted. After two years of testing, I moved the C31XR to 35' on a crankup
tower and installed a 5 element 20M monobander on a 45' boom in the vacated
position @56'. The major improvement to DX performance from this switch was
not on 20M as most would expect, it was on 15 and 10M because of putting the
tribander at an optimized height for my terrain. I am a b
eliever in HFTA for helping analyze antenna performance on rugged terrain. I
just wish we could make it do verticals! 73 Charlie N8RR
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