Topband: Modeling "Ground" and losses

[Tom W8JI]

>>>The source of the r-f current flowing on buried radials is the r-f 
>>>current flowing in the earth as a result of radiation from the vertical 
>>>monopole. (etc)
>
>>It seems to me that answer ignores other effects.
>
>>1.) If we remove the earth, the radials still have current.
>
> Yes, but then the origin of that current is via a direct, metallic path 
> back to the 2nd terminal of the source (transmitter), using either 
> balanced or coaxial transmission line.

I doubt any system is 100% pure with a boundary condition like a hard 
switch.

Dirt is not the same everywhere, even at one location. It probably is almost 
never the same at the surface as it is a few inches down.

Arbitrarily declaring the method current gets into the wire is a single 
method determined entirely by contact or no contact is completely illogical.

The feedpoint connection, in all cases of vertical antennas, whether the 
system is shunt fed or series fed, or even if it is an end-fed half wave, 
ties one feed terminal to the ground or counterpoise system. It has to be 
that way, and the current out  into that counterpoise (whatever the 
counterpoise is) has to be equal to the common mode current at the junction 
flowing up into the radiator.

It can't be any other way.

Contact with the earth isn't like suddenly flipping a light switch, where 
all of a sudden all of the current is magically "collected" from the dirt 
all around the antenna, and then moving the wire .000001 wavelengths up 
suddenly flips the switch the other way.

The only true case I can think of where virtually all of the current is 
returned from the soil would be where the radial wire is buried several soil 
skin depths below the surface.  We can certainly have creative license to 
**say** it is collected from the soil for any buried radial, but it pretty 
clearly isn't factual unless the wire is infinitely deep in the soil so far 
as skin depth goes.

73 Tom