Topband: Monopole Radiation Patterns, takeoff angles etc

[Richard Fry]

Guy Olinger wrote:
>It IS TECHNICALLY TRUE what you say, no argument, but of little use since 
>you don't get to keep it, UNLESS you can get it over salt water, or off a 
>mountain top. ... I can only spend take-home pay, and I can only make QSO's 
>with the take-home pattern.  I don't see anything wrong with using the 
>take-home takeoff angle as the item of conversation -- it's the one you get 
>to use.

Note in the link below that the value of the surface wave at 1 km at an 
elevation
of 50 meters is about 110 uV/m, which is not much less than the 113 uV/m 
field
shown by the NEC far-field analysis at the peak of the space wave at 1 km.

Also note that the surface wave field at 1 km in the horizontal plane 
exceeds the peak field of the space wave at 1 km in the NEC far-field 
analysis for the alleged "takeoff angle" of this radiator, per my opening 
post in this thread.  These NEC analyses are based on 5 mS/m real earth, not 
a perfect ground plane.

A point elevated 50 meters above a plane surface from another point 1 km
away on that plane surface has an elevation angle of 2.86 degrees.  And 
while
the calculated space wave is not much above zero field at that elevation and
distance, the surface wave has a much higher value there.

Unless that propagation path is obstructed by some physical object, nothing 
prevents such low-angle waves from traveling on to the ionosphere, which 
under the right conditions will result in their reflections returning to the 
earth as skywave.

Monopole radiation at such low angles is part of its take-home pattern that
also can make DX QSOs.

http://i62.photobucket.com/albums/h85/rfry-100/Space_Surface_Wave_Compare.gif