There were numerous technical write ups about stations who wanted the
maximum theoretical ground wave signal and spent big bucks to put up 5/8
wave verticals. They were always disappointed in the unexpectedly reduced
coverage area that resulted.
Most of the reasoning for this unexpected negative result was attributed
to the minor high-angle lobe produced by the 5/8 wave coming back down and
interfering with the main lower angle signal. As a result, those station
who had experimented with 5/8 wave towers usually reduced them to 1/2 wave
or less.
Somewhere in my textbooks or papers, I have a few places where verticals
around .55 wavelength are called "non-fading verticals" for that reason.
This shows how low the effective ionosphere height is and how long the
groundwave is, where the high angle lobe arrives within range of the
groundwave.
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Topband reflector - topband@contesting.com
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