Topband: arriving wave angle

[Bob Kupps]

Hi although I can visualize a transmitted 'wave angle' as the elevation of peak field strength, and its relative strength at other angles forming a "lobe" - what is the situation for sky wave signals as they are received at a far point after being refracted by the ionosphere? When we speak of an arrival angle - is that the discreet angle perpendicular to the arriving plane wave or is that the angle at which a theoretical elevation sampling antenna would receive the highest strength signal? Maybe they are one and the same. What I am trying to visualize though is the angular "width" of the arriving signal. When HFTA says a path will open at a 9 degree wave angle does anyone have any idea how the propagated signal strength falls off at other angles? I imagine both the peak angle and range of angles being propagated varies from moment to moment for a given frequency and path as the ionosphere shimmers but wonder if anyone has seen data about this question.