Reg Edwards wrote:
"Can any of you guys tell me which of the waves on the antenna does the
radiating - is it the forward or is it the backward wave?"

I agree with Cecil, "So the answer is both."

Think of a traveling wave antenna, the rhombic. When it is properly
terminated, there is no backward wave and the radiation pattern is
unidirectional. Eliminate the termination resistance and a total
reflection occurs at the antenna`s far end. Now the rhombic is a
bidirectional antenna.

Best regards, Richard Harrison, KB5WZI

Yuri, K3BU wrote:
"I ordered 19th edition of ARRL Antenna Book and followed chain of
references that led to information on page 16-7 and Fig. 9 and 10."

Excellent purchase. A series circuit tends to have the same current
throughout except when its length is significant with respect to
wavelength. A standing wave antenna has a reflected wave which makes
impedance a function of location along the antenna. So, a certain power,
incident and reflected, combine to produce voltage and current
variations on an antenna which are related to those on a transmission
line. Since radiation from an antenna occurs, power in each direction is
not constant as it tends to be on a transmission line because radiation
is taking a toll in each direction, and that`s a good thing. It`s the
purpose of the antenna.

Coil Q is important to efficiency if any part of the XL/R is loss
resistance and not radiation resistance. Radiation resistance is the
purpose of the antenna.

My ON4UN Figures are the same as Yuri`s but appear as Fig 9-22 on page
9-15. These show the current decline across a loading coil including the
obvious case of a solenoid used as an antenna where the entire current
distribution is within the continuous loading coil.

The ARRL Antenna Book has been exposed to scrutiny for many years. By
the 19th edition it`s a safe bet that moat of it is correct (without
consideration of "strings", 5 dimensions, or 11 parallel universes).

From what I`ve seen of ON4UN`s book, he got it right too.

Best regards, Richard Harrison, KB5WZI

On 30 Oct 2003 13:59:54 GMT, oSaddam (Yuri Blanarovich)
wrote:

Richard KB7QHC wrote:

This speaks more of simple Resistive heat loss supported by your own
direct observation of:
I fried the loading coil with 600W into Hustler resonator,
melting heat-shrink tubing and wire at the bottom of the coil.

The point is, if the current was constant or close to it, you would not see the
difference as we see it. Heat rises to the top, if anything the top would be
warmer if the current was constant.

Hi Yuri,

Your testimony contradicts your sentiments. You offer
incontrovertible evidence of heat at the bottom of the coil explicitly
in your statement above, and this below:

Simple way to test it, transmit 100W to 80m Hustler resonator, and feel the
coil. Even insensitive people can feel the significant difference in
temperatures. Put 500W to it for longer period and watch the heatshrink tubing
shrivel from the bottom up. This eliminates all the "errors" with meters to
prove the point.

You are using a thermocouple which is sensitive to heat, the heat of
coil loss will inflate the reading. You have twice offered heat at
the bottom of the coils that correlate strongly with inflated current
values from a caloric sensor. You have no other thermocouple data
supporting the nature of the current distribution, just the isolated
section you find attractive. Put simply, your measurements have no
reference (readings from the entire length of the radiator).

You went to some trouble to offer testimonial from reference sources
on the nature of that distribution, but you did not measure it confirm
your testing. Two readings in isolation do not prove you have 100mA
into the bottom when there is only one reading below the coil.

If you are not interested in obtaining those remaining readings of
that current distribution, then you have a poor case.

73's
Richard Clark, KB7QHC

oSaddam (Yuri Blanarovich) wrote in message ...
NM5K

Dunno, I think it varies. But I sort of agree with Tom, I think it's
fairly constant across the coil.

MEASURE or FEEL it! Or disprove what W5DXP is saying.

Dunno, he seems to be saying about the same thing. It depends where
the coil is mounted.

It appears that current drop is proportional to the current drop in the section
of the antenna that is "missing" - replaced by the coil. You can express it in
electrical degrees and it appears to correspond to cosine distribution.

I could buy that to an extent I guess. But say if you had a top loaded
vertical, with linear current distribution, the current across the
coil should be appx equal no matter where the coil is placed. But if
no top loading, maybe so.. MK

Incorrect. HEAT does not rise at all, however hot gas or hot liquid
will rise in response to gravity. This has nothing to do with a loading
coil made from solid parts.

--
Bill, W7TI

Incorrect, incorrect.
If we suppose the loading coil is heating up equally (the flat earth society
argument), it heats air immediately surrounding it. Air is heating up, rises up
as you say, as it rises it picks up the other air that is heating up and they
rise together. As they progress, they heat up rest of the coil on the way up,
with the result being that the top should be warmer (hotter) than the bottom.

If we have quarter wave whip with loading coil, and the bottom contrary to the
above mechanism is warmer, thet ergo ipso there must be more current flowing in
the bottom part of the coil, confirming what we say.

Yuri, K3BU/m

You are using a thermocouple which is sensitive to heat, the heat of
coil loss will inflate the reading. You have twice offered heat at
the bottom of the coils that correlate strongly with inflated current
values from a caloric sensor. You have no other thermocouple data
supporting the nature of the current distribution, just the isolated
section you find attractive. Put simply, your measurements have no
reference (readings from the entire length of the radiator).


The bottom meter is below the coil, so there is no heat heating up the
thermocoupled meter. If you insert the meters some distance away from the coil,
you would see the corresponding readings showing the difference between the top
and bottom. Arguments that heat or magnetic field affect the thermocouple RF
ammeters are just not realistic.

You went to some trouble to offer testimonial from reference sources
on the nature of that distribution, but you did not measure it confirm
your testing. Two readings in isolation do not prove you have 100mA
into the bottom when there is only one reading below the coil.


I did just rough test with one of my meters (has 8 A), flipping the coil and I
can see some deflection at the bottom and none at the top with 100 W into the
antenna. W9UCW et al did hundreds of measurements and showed just some
examples.

If you are not interested in obtaining those remaining readings of
that current distribution, then you have a poor case.


My "case" is to bring this to attention of those who are still "knowing" that
the current in loading coils is the same at both ends. If they doubt, they can
do their own measurements and see what it is, or show us where we are wrong.
Again, ON4UN in his Low Band DXing book has it right, ARRL Antenna Book has it
wrong and is perpetuating 50 year old misconception.

Just MEASURE or FEEL it!

73's
Richard Clark, KB7QHC

Yuri, K3BU/m

I could buy that to an extent I guess. But say if you had a top loaded
vertical, with linear current distribution, the current across the
coil should be appx equal no matter where the coil is placed. But if
no top loading, maybe so.. MK


Top loaded vertical does not have LINEAR current distribution, that is another
simplification, fallacy. Current in the radiator has cosine distribution. At
the base, there is not much difference, just like in cosine of the angle
corresponding to the electrical length of radiator at that point.

Again, this subject of current distribution is important in optimizing the
antenna design by fine tuning the position of the loading coil in the antenna,
combination with top loading etc. Morew current flowing in the radiating part
of the antenna - the stronger the field and louder signal.

The "linear" current distribution mentioned in ARRL Compendium and Antenna Book
is the simplification propagated from Belrose's 1955 QST article. It is close,
but not exact and introduces confusion as it is demonstrated by the flat earth
society.

Yuri, K3BU/m

Yuri wrote,

Again, this subject of current distribution is important in optimizing the
antenna design by fine tuning the position of the loading coil in the
antenna,
combination with top loading etc. Morew current flowing in the radiating part
of the antenna - the stronger the field and louder signal.

What is "the radiating part of the antenna," Yuri?
73,
Tom Donaly, KA6RUH

On 30 Oct 2003 23:19:00 GMT, oSaddam (Yuri Blanarovich)
wrote:


You are using a thermocouple which is sensitive to heat, the heat of
coil loss will inflate the reading. You have twice offered heat at
the bottom of the coils that correlate strongly with inflated current
values from a caloric sensor. You have no other thermocouple data
supporting the nature of the current distribution, just the isolated
section you find attractive. Put simply, your measurements have no
reference (readings from the entire length of the radiator).


The bottom meter is below the coil, so there is no heat heating up the
thermocoupled meter
....
Just MEASURE or FEEL it!


Hi Yuri,

As I said, your testimony contradicts your sentiments (for the third
time now). As you offer no inclination to provide more data (a
complete survey along the entire length of the radiator using the
thermocouple devices), this is not much in the way of proof.

73's
Richard Clark, KB7QHC

On 30 Oct 2003 22:59:26 GMT, oSaddam (Yuri Blanarovich)
wrote:

If we suppose the loading coil is heating up equally

Hi Yuri,

You have already testified twice that it does not - so why IF it
around?
1.)
If you trasmit for short period of time (not
enough for heat to equalize) and feel it, or use thermal strips to check
temperature, you would see the taper in the current from bottom to top. It is
in order of 50%, not negligible.
2.)
Put 500W to it for longer period and watch the heatshrink tubing
shrivel from the bottom up.

73's
Richard Clark, KB7QHC