Topband: Ground mounted 1/2 wave

[Tom W8JI]

----- Original Message ----- 
From: "ZR" <zr at jeremy.mv.com>

This is where I think the problem is. You say:

> ** Since the TOA is established at almost ground zero, radials can 
> increase the energy at angles that would
> otherwise be attenuated.

That is incorrect.

Radials, unless they radiate through some flaw such as a single radial 
system that allows far field radiation, do not meaningfully affect TOA. This 
is all over the place in all sorts of books, and a knowlege of reflections 
and angles would tell us the idea radials close to the antenna affect TOA 
makes no sense with any vertical, unless the feedline or radials are acting 
like antennas in the far field.

The elevation pattern is established some distance out from the antenna.

Radials almost exclusively (if reasonably balanced or in large enough 
numbers to have minimal currents) alter efficiency, nothing else.

>It is the explanation that confuses many since the facts about radials is 
>real. A few
> on here seem to be unable to seperate the feedpoint measurements and 
> calculations from radiated losses at
> the lowest angles. An improved ground away from the base doesnt even have 
> to be connected to it to be effective.

The elevation pattern is formed by the distribution of current in the 
vertical element and the ground out several wavelengths. The lower the 
angle, and more elevated the high current area, the further out the area 
responsible for pattern formation moves.

If you don't trust multiple people on this reflector, you might read 20-17 
in the Antenna Engineering Handbook by Jasik, and dozens of other 
engineering sources listed in the references at the end of that chapter. 
Quoting Jasik, "ground system losses dissipate a portion of the input power 
and reduce the field radiated from the antenna. These losses are equivalent 
to the power dissipated in a resistor is series with the antenna impedance"

There are many good references out there. Even the ARRL Handbooks have 
addressed this issue.