Chuck, WA7RAI wrote:
"I get the impression that what you are doing is placing any number of
elements on a .1 lambda boomlength in order to determine if the close
proximity EM interactions produce more gain than just the standard 2
elements would on that same boom length."

Close element spacing was once used to make a class called supergain
antennas. Kraus notes in his 1950 "Antennas" that: "Until the antenna
power was considered by G.H. Brown (Proc. I.R.E. January, 1937) the
advantages of closely spaced elements were not appreciated." The W8JK
array by Kraus is closely spaced. Kraus notes a downside: "Hence, a
considerable reduction in radiating efficiency may result from the
presence of any loss resistance, (The radiatiation resistance drops as
spacing shrinks.)" See "Antennas" edition 3 for close spaced antennas.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote in message
...
"Hence, a
considerable reduction in radiating efficiency may result from the
presence of any loss resistance, (The radiatiation resistance drops as
spacing shrinks.)" See "Antennas" edition 3 for close spaced antennas.

Best regards, Richard Harrison, KB5WZI


Hi Richard,

Indeed. And Kraus' speculation in this
regard has been the basis for some
debate, if I recall.

It is my opinion that .1 lambda spacing
has been somewhat established as
optimum spacing for a 2 el yagi with a
director - and I get the impression that
this is the basic structure that Art is
using as a benchmark.

Perhaps the next step is to determine
whether the modeled gain Art is getting
is a result of artifacts or not.

73 de Chuck, WA7RAI

wrote in message
newsYeed.289823$MQ5.38322@attbi_s52...
YES

Hi Art,

To be honest, I suspect you will not
find much data IRT to what you are
doing here. However, I suggest
making some effort to determine if the
extra gain you are seeing in the
models are a result of artifacts or not,
would be helpful.

If you haven't already done do, I would
be trying frequency sweeps over a
limited bandwidth, and scaling them to
higher frequencies to see if the results
remain consistent. If not, this could be
an indication of artifacts.

I get the impression you are making
physical models to test as well.

Perhaps scaling to a much higher freq,
say 50 or 145 mHz or so, would make
FS tests more manageable.

The goal, is to simply determine if the
gain of the experimental structure is
greater than that of the benchmark
(the 2 el yagi) - measuring the exact
amount, should be of no real concern
at this point.

73 de Chuck, WA7RAI

"Chuck" wrote in message
newsCyed.11049$6P5.8562@okepread02...

wrote in message
newsYeed.289823$MQ5.38322@attbi_s52...
YES

Hi Art,

snip.

If you haven't already done do, I would
be trying frequency sweeps over a
limited bandwidth, and scaling them to
higher frequencies to see if the results
remain consistent. If not, this could be
an indication of artifacts.

I'l think about that


I get the impression you are making
physical models to test as well.

Perhaps scaling to a much higher freq,
say 50 or 145 mHz or so, would make
FS tests more manageable.

The goal, is to simply determine if the
gain of the experimental structure is
greater than that of the benchmark
(the 2 el yagi) - measuring the exact
amount, should be of no real concern
at this point.

73 de Chuck, WA7RAI

Chuck, I am an experimentor, I am not advocating changing the aproach to
antennas by amateurs
When light weight fishing poles on E Bay became less than a dollar a foot
I was able to get rid of most of my aluminum stock.When I got Beasely's
NEC Pro program all prior constraints regarding antenna experimenting
were removed (ala aluminum or copper foil). Last year I made a 160M dipole
that was rotatable
and frequency controlable with moveable bandwidth, I succeeded, but it still
was a large structure
and winter provided many unwanted occasions to repair the unexpected. This
winter I am being
less ambitious and am confining myself to a 8 foot boom. First I was to
check if more elements
can improve the gain. From prior experiments I knew that feed impedance can
be change upwards
by placing an element close the rear of the feed dipole which is contrary to
the ARRL handbook.
I also was aware from previous experiments that element diameter was very
important if one is
not controlled by mechanical requirements. I also knew from reading that in
stacking when
only the bottom array was being used one obtained protection from static
noise so this would
also be a good opportunity to have one element say 30 inches higher than the
rest on the mast
which would be part of the original array to give room for experimentation.
My present model has a gain of 13 dbi at a ht of 820 inches over perfect
ground and is less than 2:1
across the audio portion of 20 M. The number of elements is six which
suggest things are heavy but with
fishing poles it is extremely light. ( note, fishing poles when ice laden
bend as if it had caught a fish and
the ice then slides off) I have not used the f/b to rest upon as I believe
that the lower lobe at the rear is not
important where the second lobe is when considering direction of
propagation.
So thats it Chuck, I enjoy myself with playing with antennas to find out
things for myself as I have
more options at hand that the ARRL have not considered as yet and thus are
not held hostage
to the knoweledge of the many psuedo experts who thou knoweledgable about
the past which is very
usefull have decided that there is no future since all is known. By the way
with the advent of cheap cameras
$30 it is easy to place a SWR meter or power meter right at the feed point
and eliminate questions regarding
transmission lines.
Regards
Art

wrote in message
news:MzAed.448084$Fg5.138935@attbi_s53...

"Chuck" wrote in message
newsCyed.11049$6P5.8562@okepread02...

wrote in message
newsYeed.289823$MQ5.38322@attbi_s52...
YES

Hi Art,

snip.

If you haven't already done do, I would
be trying frequency sweeps over a
limited bandwidth, and scaling them to
higher frequencies to see if the results
remain consistent. If not, this could be
an indication of artifacts.

I'l think about that


I get the impression you are making
physical models to test as well.

Perhaps scaling to a much higher freq,
say 50 or 145 mHz or so, would make
FS tests more manageable.

The goal, is to simply determine if the
gain of the experimental structure is
greater than that of the benchmark
(the 2 el yagi) - measuring the exact
amount, should be of no real concern
at this point.

73 de Chuck, WA7RAI

Chuck, I am an experimentor, I am not advocating changing the aproach to
antennas by amateurs

Hi Art,

I apologize if I gave that impression.


When light weight fishing poles on E Bay became less than a dollar a foot
I was able to get rid of most of my aluminum stock.When I got Beasely's
NEC Pro program all prior constraints regarding antenna experimenting
were removed (ala aluminum or copper foil). Last year I made a 160M
dipole that was rotatable and frequency controlable with moveable bandwidth,
I succeeded, but it still was a large structure and winter provided many
unwanted occasions to repair the unexpected. This winter I am being less
ambitious and am confining myself to a 8 foot boom. First I was to check if
more elements can improve the gain. From prior experiments I knew that
feed impedance can be change upwards by placing an element close the
rear of the feed dipole which is contrary to the ARRL handbook.
I also was aware from previous experiments that element diameter was very
important if one is not controlled by mechanical requirements. I also knew
from reading that in stacking when only the bottom array was being used one
obtained protection from static noise so this would also be a good opportunity
to have one element say 30 inches higher than the rest on the mast which
would be part of the original array to give room for experimentation.
My present model has a gain of 13 dbi at a ht of 820 inches over perfect
ground and is less than 2:1 across the audio portion of 20 M. The number of
elements is six which suggest things are heavy but with fishing poles it is
extremely light. ( note, fishing poles when ice laden bend as if it had caught a
fish and the ice then slides off) I have not used the f/b to rest upon as I believe
that the lower lobe at the rear is not important where the second lobe is when
considering direction of propagation.

A 2:1 VSWR bandwidth over the 20m
phone portion implies a good Q, but
aren't you even a bit curious if the gain is
indeed as high as 13 dBi?

I seem to recall from years ago, a yagi
that had several close spaced directors on
a relatively short boom - I just can't recall if
it was commercial, in an article, or any
other significant details about it.

So thats it Chuck, I enjoy myself with playing with antennas to find out things
for myself as I have more options at hand that the ARRL have not considered
as yet and thus are not held hostage to the knoweledge of the many psuedo
experts who thou knoweledgable about the past which is very usefull have
decided that there is no future since all is known. By the way with the advent
of cheap cameras $30 it is easy to place a SWR meter or power meter right
at the feed point and eliminate questions regarding transmission lines.
Regards
Art


The camera idea is a good one

There are always new things to learn...

My latest experiments have produced
some unusual antennas:

A unique dipole that does not inductively
couple with surrounding conductors (the
perfect attic dipole), that can be 'tuned'
at ground level, which, at first glance,
appears to have a somewhat omni-
directional pattern.

A reduced-noise (E-field loaded) vertical
for 40m with a VSWR bandwidth of 1.3:1
from 7.0 to 7.3 mHz, (it's not a dummy
load as one would generally deduce from
the above description), and has proven to
be as good a performer on DX and local
as my conventional top loaded vertical.

The conventional vertical sees a noise
level here of around S-7 or greater, and
the E-field loaded vertical, around S-3 to
S-5 (on IC-756, normal BW, no NB, no
DSP).

Neither of these were developed using
computer modeling, though.

Keep up the fun...

73 de Chuck, WA7RAI

"Chuck" wrote in message

A reduced-noise (E-field loaded) vertical
for 40m with a VSWR bandwidth of 1.3:1
from 7.0 to 7.3 mHz, (it's not a dummy
load as one would generally deduce from
the above description), and has proven to
be as good a performer on DX and local
as my conventional top loaded vertical.

What is E-field loaded? Not sure what you mean with that...

The conventional vertical sees a noise
level here of around S-7 or greater, and
the E-field loaded vertical, around S-3 to
S-5 (on IC-756, normal BW, no NB, no
DSP).

I'd be very leary...Also would depend on the polarization of the
noise, and any possible changes in the pattern...But in general, if a
certain vertical picks up more far field noise than another, it's the
superior vertical. Noise is rf like any other signal. So unless I'm
missing something here, the conventional antenna should also receive
the *desired* signal better than the low noise version. And being
things are generally reciprical, it should probably transmit a better
signal also...How careful have your on the air tests been? Are you
quickly A/B'ing using a switch?
Needless to say, I'm kind of dubious of the claims of equal
performance. Unless the noise was common mode or polarity related,
I've never seen an antenna that received lower noise, outdo one that
picked up more noise. If the change is not efficiency related, that
would leave me to think that your vertical pattern is being skewed
somewhat, and is more horizontally polarized than the other, and thus
, picks up less vertically polarized noise. If thats not the case, I
would think the low noise version is less efficient. Just my opinion
tho...

Neither of these were developed using
computer modeling, though.

Neither were my comments...:/ MK

"Chuck" wrote in message
news:B3Ted.11167$6P5.7719@okepread02...

wrote in message
news:MzAed.448084$Fg5.138935@attbi_s53...

"Chuck" wrote in message
newsCyed.11049$6P5.8562@okepread02...

wrote in
message
newsYeed.289823$MQ5.38322@attbi_s52...
YES

Hi Art,

snip.

If you haven't already done do, I would
be trying frequency sweeps over a
limited bandwidth, and scaling them to
higher frequencies to see if the results
remain consistent. If not, this could be
an indication of artifacts.

I'l think about that


I get the impression you are making
physical models to test as well.

Perhaps scaling to a much higher freq,
say 50 or 145 mHz or so, would make
FS tests more manageable.

The goal, is to simply determine if the
gain of the experimental structure is
greater than that of the benchmark
(the 2 el yagi) - measuring the exact
amount, should be of no real concern
at this point.

73 de Chuck, WA7RAI

Chuck, I am an experimentor, I am not advocating changing the aproach to
antennas by amateurs

Hi Art,

I apologize if I gave that impression.


When light weight fishing poles on E Bay became less than a dollar a
foot
snip

A 2:1 VSWR bandwidth over the 20m
phone portion implies a good Q, but
aren't you even a bit curious if the gain is
indeed as high as 13 dBi?

Funnily today I changed the model slightly
and the gain exceeded 14 dbi with an increase in Q
So this is the model that I am going to make but
with the anticipation that by curving the elements
I will narrow the beam width. It shows 66 degrees
at the moment and a take off angle of 12 degrees.
It should be up in a few weeks. When I test I will look for
feed impedance and lobe width using a laptop program
with a distant signal.




I seem to recall from years ago, a yagi
that had several close spaced directors on
a relatively short boom - I just can't recall if
it was commercial, in an article, or any
other significant details about it.

It may have been the 13 element I made for 20 M
on I think a 80 foot boom and that was the first time I used
two reflectors to get a 50 ohm feed.
I seem to remember that Roy modelled that also on EZNEC
or is it ELNEC and he confirmed the 50 ohm feed as did
my modelling and the actual antenna.This was about 10 years ago.




So thats it Chuck, I enjoy myself with playing with antennas to find out
things
for myself as I have more options at hand that the ARRL have not
considered
as yet and thus are not held hostage to the knoweledge of the many
psuedo
experts who thou knoweledgable about the past which is very usefull have
decided that there is no future since all is known. By the way with the
advent
of cheap cameras $30 it is easy to place a SWR meter or power meter
right
at the feed point and eliminate questions regarding transmission lines.
Regards
Art


The camera idea is a good one
Yes I first used a micro video camera for direction of my prop pitch rotor
and then to observe stepping motor angles on capacitors


There are always new things to learn...

My latest experiments have produced
some unusual antennas:

A unique dipole that does not inductively
couple with surrounding conductors (the
perfect attic dipole), that can be 'tuned'
at ground level, which, at first glance,
appears to have a somewhat omni-
directional pattern.

A reduced-noise (E-field loaded) vertical
for 40m with a VSWR bandwidth of 1.3:1
from 7.0 to 7.3 mHz, (it's not a dummy
load as one would generally deduce from
the above description), and has proven to
be as good a performer on DX and local
as my conventional top loaded vertical.

The conventional vertical sees a noise
level here of around S-7 or greater, and
the E-field loaded vertical, around S-3 to
S-5 (on IC-756, normal BW, no NB, no
DSP).

Neither of these were developed using
computer modeling, though.

Keep up the fun...

Well that seems all very interesting but you are very
much out of my league which is just as well because
mention of E and H waves agitates the experts more than
my talk of coupling does

Art

73 de Chuck, WA7RAI

Chuck, WA7RAI wrote:
"Indeed. And Kraus` speculation in this regard has been the basis for
some debate if I recall."

Kraus gets support from Terman`s 1955 edition on page 906:
"A characteristic of all close-spaced arrays is that as size to antenna
gain is reduced, the radiation resistance also goes down; this is
illustrated by Fig. 23-36."

Best regards, Richard Harrisopn, KB5WZI

Richard Harrison wrote in message
...
Chuck, WA7RAI wrote:
"Indeed. And Kraus` speculation in this regard has been the basis for
some debate if I recall."

Kraus gets support from Terman`s 1955 edition on page 906:
"A characteristic of all close-spaced arrays is that as size to antenna
gain is reduced, the radiation resistance also goes down; this is
illustrated by Fig. 23-36."

Best regards, Richard Harrisopn, KB5WZI


Hi Richard,

No one can argue with Kraus and Terman
or anyone else on this. What is "debatable"
is: at what point does radiation resistance
become too low - where high current losses
cancels any gain achieved by the tight
coupling. This is JMO, of course.

73 de Chuck, WA7RAI

wrote in message
news:08_ed.243129$wV.18192@attbi_s54...

"Chuck" wrote in message
news:B3Ted.11167$6P5.7719@okepread02...

...
A 2:1 VSWR bandwidth over the 20m
phone portion implies a good Q, but
aren't you even a bit curious if the gain is
indeed as high as 13 dBi?

Funnily today I changed the model slightly
and the gain exceeded 14 dbi with an increase in Q
So this is the model that I am going to make but
with the anticipation that by curving the elements
I will narrow the beam width. It shows 66 degrees
at the moment and a take off angle of 12 degrees.
It should be up in a few weeks. When I test I will look for
feed impedance and lobe width using a laptop program
with a distant signal.

I am curious: how are you handling the
driven element's low input impedance?

...
Keep up the fun...

Well that seems all very interesting but you are very
much out of my league

Hardly

73 de Chuck, WA7RAI