Topband: Best angle of radiation ?

[Richard Fry]

Lloyd Berg N9LB wrote:
>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.

Note that the above effects are not present for AM BCB stations operating 
with fairly low power (say 5 kW and less), and/or on higher BC frequencies 
and/or where earth conductivity is poor.

In those cases the groundwave has already fallen below the ambient r-f noise 
level within the radius where those high-angle skywaves start returning to 
the earth -- so no self-interference occurs.

R. Fry