On 05/05/2012 03:51 PM, Richard Fry wrote:
> It is universally common for the highest radiated fields launched by
> vertical monopoles to occur in the elevation sector between the horizontal
> plane and 5 degrees above the horizontal plane. This is a natural
> consequence of the summation of individual fields generated along the height
> of the monopole by the r-f current flow there.
>
> The graphic linked below is taken from Radio Engineers' Handbook by F. E.
> Terman (1st Ed), showing that the skywave from the monopole of a typical AM
> broadcast station that serves the greatest single-hop range leaves the
> radiator at elevation angles of 5 degrees and less.
>
> This will be true for HF monopoles, also, but the range would depend on the
> height of the layer of the ionosphere where the reflection takes place.
This really depends on how good the ground system below
the vertical is.
If you have an exceptionally good ground system, you can
get those 5 degree takeoff angles.
More typical for ham radio setups are takeoff angles
between 15 and 30 degrees.
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