[TZ] Elevated radials vs buried ones

[Cowboy]

On Wednesday 18 May 2016 11:00:45 pm Harold Hallikainen wrote:
> Interesting subject! The elevated "ground radials" seem like we're driving
> the center of a dipole turned vertical with one side "flared out." 

 That's not a bad way to think of any vertical whether using an
 elevated radial counterpoise, building roof, or a conventional
 ground mounted broadcast vertical.

> The 
> relationship to "ground" is interesting. I always think of a horizontal
> dipole or inverted V or similar as having a drivepoint that is balanced
> with respect to ground. 

 Technically, with respect to the universe.
 The "ground plane" is unbalanced by definition, which lends itself
 well to an unbalanced feed.
 
> suspect the voltage on the radials at the base are perhaps 1/4 the voltage
> at the base of the tower with respect to ground. The radials probably
> reach ground potential part way down the radial, then start going up
> again. Just guessing here.

 The voltage and current distribution is theoretically the same as the
 other half. Minimal voltage and maximum current at the feed point,
 with minimal current and maximum voltage at the far end.
 Actually, maximum voltage and minimum current always occurs
 at the far end, though the converse depends on the electrical length.

> On losses, it seems that having fewer radials would not necessarily
> increase loss but would perhaps just change the driving point impedance.
> We might think of a tower with one radial as an inverted V turned on its
> side. If one side is particularly close to ground, we may get losses due
> to that (current through a resistive material).

 That's the extreme case, yes.
 The current is distributed about the vertical, so in the case you present,
 the majority of the return currents are through lossy earth.

> Anyway, interesting stuff to think about.

 There is far less understanding of these things than one might expect
 among supposedly educated and experienced engineers.
 Some, it's understandable. That's why we have consultants.
 Others, not so much.
 I'd expect a Ron Rackley to understand these things, but not so much
 about audio processing.
 I would not expect Frank Foti, or Bob Orban to understand much about
 antenna theory, ( though they might ) but I would expect them to know
 considerable about audio paths and processing.
 None the less, the brain exercise is good for us all. ( IMHO )
 Beware dragons, for thou art crunchy, and good with catsup !

-- 
Cowboy