View Single Post
  #270   Report Post  
Old November 5th 04, 11:07 PM
Richard Clark
 
Posts: n/a
Default

On Fri, 05 Nov 2004 13:37:27 -0800, Jim Kelley
wrote:

Point being that antenna gain has spatial implications which Rr by
itself could not provide in the solutions.


Hi Jim,

Not sure where this is going, so I will stand with my own statements.

One should conclude from your results (very nice work, by the way) that
the modeler apparently doesn't figure Xl as contributing to the
radiation resistance.


Again, words. I would offer that Xl does not adjust Rr (insofar as it
does adjust drivepoint Z). Let me add - much (there are miniscule
differences).

But isn't that basically the crux of the argument
here - whether or not that is in fact the case? If not, then we would
have to conclude that loading coil has zero physical and electrical
length, and that the impedance is constant from one end to the other.


As I say above, it is not a difference of ZERO it is a miniscule
difference (with a negative correlation). I will leave it to others
to recapture (or diminish) gain through helix building. I am
satisfied those returns will be equally diminutive.

Obviously I could be wrong, but I think those are the assumptions made
in your modeling software.


We both could be wrong. No one has yet to step up to the bar and
offer work in kind.

On the other hand, if the impedance of the
coil is not constant from one end to the other, and it in fact does have
some real physical and/or electrical length, then I think the radiation
resistance of the antenna would have to be effected by its presence in
the circuit. That is, if indeed Ro is the integral of disributed r
along the entire physical and/or electrical length of the antenna
(credit for that formula going to an esteemed contributor to this
newsgroup earlier today). Or perhaps more concisely put, if the loading
coil itself contributes to the field radiating from the antenna, then it
should likewise have a Rr associated with it. The converse would of
course still be true.


This returns us to matters of degree. By simple observation comparing
the standard full sized radiator to ANY of the iterations, it is
obvious that nothing significant can be said of the physicality of the
load, much less its contribution. In other words, is there some
magical coil or magical placement that would create a short
super-radiator that exceeds the performance of the standard
quarterwave? [no here can recognize a eh/cfa claim?]

Let's put a handicap on this. Is there some magic combination of
coil/position that would even EQUAL the performance of the standard
quarterwave?

73's
Richard Clark, KB7QHC