[BC] Directional Antenna Proofs - Ground systems. <SoM0Gk0c0>

[Cowboy]

On Thursday 21 June 2012 03:30:03 pm jpotter at jpotter.com wrote:
> Messrs. Fry & Meuser:
> 
> Roger your opinions, thank you. But my question begs: why use 120 radials when -- as it appears to be argued  only 2 would be satisfactory? 

 As Richard did state, the losses are much higher.
 Whether it affects directivity, or not, ( I'm in the camp that it doesn't, so long as
 they are symetrical about the feed point ) two radials would be severely less efficient.

>  I am also persuaded that this effect is independent of (1) whether the ground plane is mounted on a pole high off the ground or resting on the earth, or (2) operating frequency.  
 
 Then you'd be wron.... er.... mislead ! ( we are in the political election cycle,
 where a lie is merely "misinformed", and folks are always merely "in error" )

 It's been shown that a ground plane mounted a minimum of 7 wavelengths above
 the electrical ground surface approaches free space.
 Below that level, ground reflections are not inconsequential, and can be
 shown to affect the pattern cyclically as a portion of wavelength above that
 electrical ground surface.
 Additionally,
 The depth of the electrical ground surface is almost entirely dependent
 on frequency, ranging from the actual surface of the dirt, to several
 meters below, and as such affecting ground losses directly.

-- 
Cowboy