Topband: Ground Radials Yet Again

[Tom Rauch]

> I'm sorry, I don't follow this!   The idea is to return 
> the current and if the impedance is high it'll be all 
> volts!'
> Even laying on the ground the Q will be in the 10's.... so 
> max current return will be at resonance.

The only job of the radials is to keep fields and current 
out of the lossy earth. It isn't to "return" the maximum 
possible amount of current. The total current returned at 
the base of the antenna will always exactly equal the net 
current going up into the vertical at that same point. 
Always.

It's pretty well documented that the terminal impedance of a 
radial system at the antenna does not go hand-in-hand with 
losses. I can have a lossy ground system that presents a 
very low impedance at the antenna feedpoint, and I can 
likewise have one with a fairly high impedance that has low 
loss. This was all covered here just a few weeks ago. 
Briefly repeated we measured field strength on a 40 meter 
vertical here. With no change in the vertical at all, a 
radial system that  produced about 60 ohms of base impedance 
had slightly better efficiency than one producing under 40 
ohms.

Several others have verified this with independent 
measurements of their own.

The only way to tell if a change improved efficiency is to 
somehow measure the efficiency.

73 Tom