Interesting... so electrical length is affecting gain and EZNEC supports
it--that will probably silence those who claim the physical length is all
important... ya suppose?

Regards

--
Hay, if'n ya'll cun't konstructivly partecipete in this disscusion, haw
aboot speel-checkin it fer me?


"Cecil Moore" wrote in message
...
Buck wrote:
The SlimJim resembles the J-Pole.

And the Zepp.

I am not sure what the folded section does for it.

Folding a 1/4WL vertical raises the feedpoint impedance.
Folding a 1/2WL vertical lowers the feedpoint impedance.

A folded 1/2WL monopole has about half the end-fed feed-
point impedance of an end-fed single-wire 1/2WL monopole.
About 1250 ohms Vs 2500 ohms for 20m with mininec ground.

EZNEC sez the folded 1/2WL monopole has a slightly lower
resonant frequency and slightly higher gain. (+0.07 dB)
--
73, Cecil http://www.qsl.net/w5dxp

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On Mon, 28 Mar 2005 18:21:52 -0800, "John Smith"
wrote:

Interesting... so electrical length is affecting gain and EZNEC supports
it--that will probably silence those who claim the physical length is all
important... ya suppose?

Hi "Fred,"

It will take more than supposition and superstition.

So back to rote:
The physical size in relation to wavelength dominates launch
characteristics, NOT electrical length.

73's
Richard Clark, KB7QHC

"Richard Clark"
So back to rote:
The physical size in relation to wavelength dominates launch
characteristics, NOT electrical length.
__________________

I don't know who wrote your rote, but here is part of what Terman says on
this topic in his Radio Engineer's Handbook, p 795, referring to vertical
radiators driven against ground:

"Top loading has the same effect on the field distribution in a vertical
plane as a greater height. Thus an antenna for which H = 0.45 lambda can by
suitable top loading be made to have a field distribution in the vertical
plane that is substantially the same as for a vertical wire of H = 0.6
lambda."

Or is that what you meant?

RF

"Richard Fry" wrote So back to rote:
The physical size in relation to wavelength dominates launch
characteristics, NOT electrical length.
__________________

I don't know who wrote your rote, but here is part of what Terman
says on
this topic in his Radio Engineer's Handbook, p 795, referring to
vertical
radiators driven against ground:

"Top loading has the same effect on the field distribution in a
vertical
plane as a greater height. Thus an antenna for which H = 0.45
lambda can by
suitable top loading be made to have a field distribution in the
vertical
plane that is substantially the same as for a vertical wire of H =
0.6
lambda."

=============================

No, it doesn't !

But you could stretch "substantial" (a non-engineering term) a bit
more.

You have been warned once before about quoting Terman as the Bible.
(smiley)
----
Reg.

"Reg Edwards" wrote about the elevation pattern of a loaded vertical against
ground as being ~ the same as that of a longer, unloaded vertical, per
Terman:

No, it doesn't ! You have been warned once before
about quoting Terman as the Bible.
______________

I wonder, then, what your basis is for saying so.
At least I give a source.

Terman also publishes a formula to calculate the elevation pattern of a
shortened vertical with a top-mounted capacity ring, driven against
ground -- but it's too much to post here without mathematical notation. The
formula was credited by Terman to George H. Brown from his "A Critical Study
of Broadcast Antennas as Affected by Antenna Current Distribution" published
in the Proceedings of the I.R.E.

Terman also says that inserting a coil a bit down from the top of a
shortened vertical gives results equivalent to using a top mounted capacity
ring.

RF

On Tue, 29 Mar 2005 10:38:49 -0600, "Richard Fry"
wrote:

Terman also says
nothing about a Helical wound slim jim. Of course, this begs the
question "Why would he?"

The results are predictable, boringly so, and several have already
been down that road to no net gain. However, common sense in these
matters can be discarded if only someone offers validation, however
slim that may be from any jim. Such inventors stand on the shoulders
of dwarfs. Sorry for the allusion, as it again reprises the obvious
that physical height in relation to a standard (wavelength) dominates
the principle. However as principles and seeking validation go, no
doubt the topic will drift towards top loading dwarfs....

73's
Richard Clark, KB7QHC

"Richard Clark" wrote:
Sorry for the allusion, as it again reprises the obvious
that physical height in relation to a standard (wavelength) dominates
the principle. However as principles and seeking validation go, no
doubt the topic will drift towards top loading dwarfs...
_____________

So far you have not provided support for your statements on this subject
from any recognized antenna authority. Do you really believe that your
understanding of this, and your statements about it are better/more accurate
than those of Frederick Terman and George Brown?

RF

I must point out that although my exchange with you has been short and
seemingly pointless; you feel a necessity to place yourself in prominence,
of both your "knowledge", opinions and your person.

I hardly wish you to keep up with such tiring and pointless expenditure of
energy on your part--I have found you to only be self-serving in your
devotion to your ego, yourself and your personal endeavors to make a fool of
yourself and destroy any sense of dignity one might have been able to afford
you.

I can only speak for myself of course, but you have completely destroyed any
credibility I could have granted you and, would only accept any offerings
from you after having checked them through other sources--since this is the
case, little is to be had from giving you any further considerations at all.



Regards


--
Hay, if'n ya'll cun't konstructivly partecipete in this disscusion, haw
aboot speel-checkin it fer me?


"Richard Clark" wrote in message
...
On Tue, 29 Mar 2005 10:38:49 -0600, "Richard Fry"
wrote:

Terman also says
nothing about a Helical wound slim jim. Of course, this begs the
question "Why would he?"

The results are predictable, boringly so, and several have already
been down that road to no net gain. However, common sense in these
matters can be discarded if only someone offers validation, however
slim that may be from any jim. Such inventors stand on the shoulders
of dwarfs. Sorry for the allusion, as it again reprises the obvious
that physical height in relation to a standard (wavelength) dominates
the principle. However as principles and seeking validation go, no
doubt the topic will drift towards top loading dwarfs....

73's
Richard Clark, KB7QHC

I wonder, then, what your basis is for saying so.
At least I give a source.

===========================

Sorry Richard. I never refer to sources. Except perhaps Ohm.
There's no way of guaranteeing reliability. I work things out for
myself so you'll just have to take my word for it.

I have a remarkably small book library. Although I did buy a
second-hand copy of Terman in 1947 which I still occasionally browse
through when I'm running short of ideas. He's most comprehensive.
Which accounts for his continued popularity. But he's not God. Anyone
who has actually tried to use him will know that.

I do have volumes from A to S of notes accumulated over the last 45
years. But some papers are about telescope making which was a hobby of
mine before our night skies became polluted with vapour trails and
other fumes. And some wicked kids stole my camera.
----
Reg.

"Reg Edwards" wrote..
Sorry Richard. I never refer to sources. Except perhaps Ohm.
There's no way of guaranteeing reliability. I work things out for
myself so you'll just have to take my word for it.

I have a remarkably small book library. Although I did buy a
second-hand copy of Terman in 1947 which I still occasionally browse
through when I'm running short of ideas. He's most comprehensive.
Which accounts for his continued popularity. But he's not God.
______________

I suspect that your statement above that you never refer to sources doesn't
mean that all of your considerable knowledge is the result of your original
investigations. Even your countryman Stephen Hawking credits his sources
when he writes of scientific topics.

Terman's (Brown's) statements about the elevation patterns of loaded
verticals have been proven empirically by MW radiators for 70 years or more.
There is nothing to argue about, and certainly no reason to take the word of
anyone not willing to show conclusively how this concept is invalid. One's
word is insufficient -- even if it comes from you and/or Richard Clark.

RF