David that is quite an array of antennas. Two questions come to mind.
Why the separation of a half versus 0.6 of a wave length?
and 2 do you ground the top antenna when it is not in use or let it
float?
I have heard that the top array can remove static noise to advantage
and I was wondering how that would compare to an elevated mast that
would provide a cone of protection and thus allow use of the top array
regardless of conditions.
Regards
Art

art wrote:
David, are you saying that your three-some stack is made out of tri
banders of the same design such that a lobe null can be filled? I
believe that is exactly the coverage the poster is looking for, he
wants to be around to hear when the tree falls
Art

Dave wrote:
"Cecil Moore" wrote in message
t...
CW wrote:
I've been wondering for some time now why amateur operators don't build
their Yagi antenna's
so they can be raised and lowered about 10ft in addition to being
rotated.

Many do, using motor driven towers. In addition to lowering
their arrays when a storm hits, some raise and lower their
towers during marginal conditions to maximize signal strength.
--

its really only practical on crank up type towers, for those with guyed
towers its usually not possible.

10' change on 20m would likely not be very useful though. my hf stacks for
10/15/20 are all spaced 30' apart, 40m is spaced about 80'. even with those
height changes (which i can select instantly so i can make direct
comparisons without worrying about fading) there is often little difference
between antennas... though sometims there is a lot of difference. This
highlights the fact that often the signals arrive with a wide range of
angles, though at some times they must be in a relatively narrow range. so
having multiple antennas at different heights that can be selected in
various combinations is a handy thing to do.

Yes there is a difference, A yagi is a planar beam ie on a single plane
so the height of the array is the same for all elements in the array
which creates a major lobe or beam.
If the array is not planar such as a Quad then the elements are at
different heights
so the true or effective height of a quad antenna which is also a beam
style antenna is approximately the center point of the array or
somewhere between the top and bottom of the quad element.
The point to stand by is that the height of the feed point is
immaterial with respect to the effective height of an array. In another
post I pointed out that no matter which element is fed in a array the
effective height of the array is always the same and thus the TOA is
always the same
Regards
Art



Sal M. Onella wrote:
"CW" wrote in message
ups.com...
Fellows,

I've been wondering for some time now why amateur operators don't build
their Yagi antenna's
so they can be raised and lowered about 10ft in addition to being
rotated.
It seems to me that raising and lowering the height of a Yagi affects
the take-off angle by at least several degrees, meaning that the signal
delivery (target area) would be moved by at least many hundreds of
miles.

I don't know if this helps, but advice for TV DX says that you get
progressively improved performance until the yagi's
height-above-average-terrain (HAAT) is equal to about ten wavelengths.
(Above that HAAT, the signal strength varies up and down with further
increases in the elevation )

I never tested the idea, but if correct and it also holds for HF, there
won't ever be anybody _lowering_ a HF yagi. We would want the most height.
At the 2006 Field Day, one team had multi-band beam at 85 feet and everybody
loved it.

Before anybody tells me there is a difference between a yagi and a beam, let
me thank you in advance. I cannot formulate a sensible distinction
between them and I welcome the knowledge. I presume the terms are related
but not interchangeable.

73

On 15 Oct 2006 21:35:43 -0700, "art" wrote:

Yes there is a difference, A yagi is a planar beam ie on a single plane
so the height of the array is the same for all elements in the array
which creates a major lobe or beam.
If the array is not planar such as a Quad then the elements are at
different heights
so the true or effective height of a quad antenna which is also a beam
style antenna is approximately the center point of the array or
somewhere between the top and bottom of the quad element.
The point to stand by is that the height of the feed point is
immaterial with respect to the effective height of an array. In another
post I pointed out that no matter which element is fed in a array the
effective height of the array is always the same and thus the TOA is
always the same
Regards
Art

Hi Art,

One of the most demeaning aspects of this newsgroups concerns misunderstandings
of definitions and terminology that often leasd to unfortunate and unnecessary
arguments.

To wit: Yagi vs beam.

It's been my understanding that any combination of radiating elements intended
to radiate more energy in one direction than omni establishes a major lobe that
is called a beam. In other words, any directional system establishes a beam.
Therefore, 'beam' is generic to all directional radiators.
It then follows that 'Yagi', 'quad', 'W8JK', 'EDZ', are all 'beams' of a
particular type or configuration.

I believe it's important that correct terminology be used for the benefit of the
newcomers--would you not agree?

Walt, W2DU

Walt
I said that both antennas are beams. What I was addressing was the
height portion of the question whereas tho they are both beams the
effective height measurements were different.
i.e Planar beam versus other beams where the quad is not a planar beam.
Seems like effective height measurements contribute to most yagi /quad
comparison debates. There is also another side of the coin when
measuring effective ht and that is when a yagi is positioned vertically
where it is still planar when comparing to a quad element moved thru 90
degrees.which is now planar. If you chose to answer the posting what
part of my posting would you leave out, or question its veracity
especially after reading the total thread?
Regards
Art





Walter Maxwell wrote:
On 15 Oct 2006 21:35:43 -0700, "art" wrote:

Yes there is a difference, A yagi is a planar beam ie on a single plane
so the height of the array is the same for all elements in the array
which creates a major lobe or beam.
If the array is not planar such as a Quad then the elements are at
different heights
so the true or effective height of a quad antenna which is also a beam
style antenna is approximately the center point of the array or
somewhere between the top and bottom of the quad element.
The point to stand by is that the height of the feed point is
immaterial with respect to the effective height of an array. In another
post I pointed out that no matter which element is fed in a array the
effective height of the array is always the same and thus the TOA is
always the same
Regards
Art

Hi Art,

One of the most demeaning aspects of this newsgroups concerns misunderstandings
of definitions and terminology that often leasd to unfortunate and unnecessary
arguments.

To wit: Yagi vs beam.

It's been my understanding that any combination of radiating elements intended
to radiate more energy in one direction than omni establishes a major lobe that
is called a beam. In other words, any directional system establishes a beam.
Therefore, 'beam' is generic to all directional radiators.
It then follows that 'Yagi', 'quad', 'W8JK', 'EDZ', are all 'beams' of a
particular type or configuration.
XXXXXXXXXXXXXXXXXXXXXXXXXXX
I agree, where did I say different?
XXXXXXXXXXXXXXXXXXXXXXXXXXX

I believe it's important that correct terminology be used for the benefit of the
newcomers--would you not agree?


Yes I would agree but if one is unsure of the true terminology should
we ban all from ham radio as it has now moved from a hobby to.......
IEEE transactions on antennas ?
I believe everyone has become too picky as to who is a ham and who is
not and thus are becoming adverserial to those not fully versed in the
art. Look at the long posting regarding
antenna efficiency where everybody jumped on the electrical version of
efficiency ie transfer of electrical energy to a time variant field and
totaly ignoring the reference to pattern volume.with respect to the
main lobe portion. How on earth do electrical engineers chose
iapliances for the home when so much device energy is wasted or does
not imprint on the required use?
The majority of people on this newsgroup including newcomers are now
convinced that energy entering an array is nearly equal to the
radiation energy contained in the single main lobe and they contest
other thoughts by the use of " ratios": which is devoid of units and
relavence. Even if they didn't want to read the posting as a whole not
one looked at radiation efficiency change when viewing radiation from a
complex circuitry direction or in other words driven elements in
parallel since elements in parallel alter the resistance DC to
resistance radiation ratio ,admittedly small but there none the less. I
would admit to a review of antenna efficiency or radiator efficiency if
it was normal for radiators to be made of wood As I said earlier to
much nittpicking going on such that hams are becoming adverserial to
each other and that is to bad if we want newcomers to stay around.NUFF
SED
Art



Walt, W2DU

On 16 Oct 2006 13:06:58 -0700, "art" wrote:

Walt
I said that both antennas are beams. What I was addressing was the
height portion of the question whereas tho they are both beams the
effective height measurements were different.
i.e Planar beam versus other beams where the quad is not a planar beam.
Seems like effective height measurements contribute to most yagi /quad
comparison debates. There is also another side of the coin when
measuring effective ht and that is when a yagi is positioned vertically
where it is still planar when comparing to a quad element moved thru 90
degrees.which is now planar. If you chose to answer the posting what
part of my posting would you leave out, or question its veracity
especially after reading the total thread?
Regards
Art

Walter Maxwell wrote:
On 15 Oct 2006 21:35:43 -0700, "art" wrote:

Yes there is a difference, A yagi is a planar beam ie on a single plane
so the height of the array is the same for all elements in the array
which creates a major lobe or beam.
If the array is not planar such as a Quad then the elements are at
different heights
so the true or effective height of a quad antenna which is also a beam
style antenna is approximately the center point of the array or
somewhere between the top and bottom of the quad element.
The point to stand by is that the height of the feed point is
immaterial with respect to the effective height of an array. In another
post I pointed out that no matter which element is fed in a array the
effective height of the array is always the same and thus the TOA is
always the same
Regards
Art

Hi Art,

One of the most demeaning aspects of this newsgroups concerns misunderstandings
of definitions and terminology that often leasd to unfortunate and unnecessary
arguments.

To wit: Yagi vs beam.

It's been my understanding that any combination of radiating elements intended
to radiate more energy in one direction than omni establishes a major lobe that
is called a beam. In other words, any directional system establishes a beam.
Therefore, 'beam' is generic to all directional radiators.
It then follows that 'Yagi', 'quad', 'W8JK', 'EDZ', are all 'beams' of a
particular type or configuration.
XXXXXXXXXXXXXXXXXXXXXXXXXXX
I agree, where did I say different?
XXXXXXXXXXXXXXXXXXXXXXXXXXX

Ok Art, here's the way I saw it:

Sal Manela sez: "Before anybody tells me there is a difference between a yagi
and a beam, let me thank you in advance."

Then you replied, "Yes there is a difference,"

So Art, my response was only to refute your statement above. I don't dispute
your other statements.

Walt, W2DU

Understood
Best regards
Art



Walter Maxwell wrote:
On 16 Oct 2006 13:06:58 -0700, "art" wrote:

Walt
I said that both antennas are beams. What I was addressing was the
height portion of the question whereas tho they are both beams the
effective height measurements were different.
i.e Planar beam versus other beams where the quad is not a planar beam.
Seems like effective height measurements contribute to most yagi /quad
comparison debates. There is also another side of the coin when
measuring effective ht and that is when a yagi is positioned vertically
where it is still planar when comparing to a quad element moved thru 90
degrees.which is now planar. If you chose to answer the posting what
part of my posting would you leave out, or question its veracity
especially after reading the total thread?
Regards
Art

Walter Maxwell wrote:
On 15 Oct 2006 21:35:43 -0700, "art" wrote:

Yes there is a difference, A yagi is a planar beam ie on a single plane
so the height of the array is the same for all elements in the array
which creates a major lobe or beam.
If the array is not planar such as a Quad then the elements are at
different heights
so the true or effective height of a quad antenna which is also a beam
style antenna is approximately the center point of the array or
somewhere between the top and bottom of the quad element.
The point to stand by is that the height of the feed point is
immaterial with respect to the effective height of an array. In another
post I pointed out that no matter which element is fed in a array the
effective height of the array is always the same and thus the TOA is
always the same
Regards
Art

Hi Art,

One of the most demeaning aspects of this newsgroups concerns misunderstandings
of definitions and terminology that often leasd to unfortunate and unnecessary
arguments.

To wit: Yagi vs beam.

It's been my understanding that any combination of radiating elements intended
to radiate more energy in one direction than omni establishes a major lobe that
is called a beam. In other words, any directional system establishes a beam.
Therefore, 'beam' is generic to all directional radiators.
It then follows that 'Yagi', 'quad', 'W8JK', 'EDZ', are all 'beams' of a
particular type or configuration.
XXXXXXXXXXXXXXXXXXXXXXXXXXX
I agree, where did I say different?
XXXXXXXXXXXXXXXXXXXXXXXXXXX

Ok Art, here's the way I saw it:

Sal Manela sez: "Before anybody tells me there is a difference between a yagi
and a beam, let me thank you in advance."

Then you replied, "Yes there is a difference,"

So Art, my response was only to refute your statement above. I don't dispute
your other statements.

Walt, W2DU

that separation comes about from the spacing of guy wires on the rohn towers
they are on. it also happens to work out reasonably well with the elevation
pattern software since that many antennas fairly well covers the whole range
of take off angles from new england to most of the world.

all my yagis are completely grounded designs anyway, so there is no need to
further ground them when not in use. when there is rain or snow static the
top one often becomes too noisy to use while lower ones are just fine...
another good reason to rotate the bottom antennas (except on 40m where it
won't turn under the guy wires).



"art" wrote in message
ps.com...
David that is quite an array of antennas. Two questions come to mind.
Why the separation of a half versus 0.6 of a wave length?
and 2 do you ground the top antenna when it is not in use or let it
float?
I have heard that the top array can remove static noise to advantage
and I was wondering how that would compare to an elevated mast that
would provide a cone of protection and thus allow use of the top array
regardless of conditions.
Regards
Art

art wrote:
David, are you saying that your three-some stack is made out of tri
banders of the same design such that a lobe null can be filled? I
believe that is exactly the coverage the poster is looking for, he
wants to be around to hear when the tree falls
Art

Dave wrote:
"Cecil Moore" wrote in message
t...
CW wrote:
I've been wondering for some time now why amateur operators don't
build
their Yagi antenna's
so they can be raised and lowered about 10ft in addition to being
rotated.

Many do, using motor driven towers. In addition to lowering
their arrays when a storm hits, some raise and lower their
towers during marginal conditions to maximize signal strength.
--

its really only practical on crank up type towers, for those with guyed
towers its usually not possible.

10' change on 20m would likely not be very useful though. my hf stacks
for
10/15/20 are all spaced 30' apart, 40m is spaced about 80'. even with
those
height changes (which i can select instantly so i can make direct
comparisons without worrying about fading) there is often little
difference
between antennas... though sometims there is a lot of difference. This
highlights the fact that often the signals arrive with a wide range of
angles, though at some times they must be in a relatively narrow range.
so
having multiple antennas at different heights that can be selected in
various combinations is a handy thing to do.

"Sal M. Onella" wrote in message
news:w3DYg.5744$gM1.5721@fed1read12...

"CW" wrote in message
ups.com...
Fellows,

I've been wondering for some time now why amateur operators don't build
their Yagi antenna's
so they can be raised and lowered about 10ft in addition to being
rotated.
It seems to me that raising and lowering the height of a Yagi affects
the take-off angle by at least several degrees, meaning that the signal
delivery (target area) would be moved by at least many hundreds of
miles.

I don't know if this helps, but advice for TV DX says that you get
progressively improved performance until the yagi's
height-above-average-terrain (HAAT) is equal to about ten wavelengths.
(Above that HAAT, the signal strength varies up and down with further
increases in the elevation )

I never tested the idea, but if correct and it also holds for HF, there
won't ever be anybody _lowering_ a HF yagi. We would want the most
height.
At the 2006 Field Day, one team had multi-band beam at 85 feet and
everybody
loved it.

no, it doesn't hold for hf. tv dx is basically a line of sight vhf/uhf type
of propagation where height is everything. the higher you can go the
better, i don't know where 10 wavelengths came from since that is actually
pretty low on the higher uhf channels! on hf you can't get high enough to
get away from the ground reflection effects so you might as well put them to
good use. And yes, when bands like 10/15/20m are wide open from new england
to europe the best antennas are often the lowest ones here... i.e. my yagi
at 30' on 10m will have much stronger signals than the ones at 60, 90, or
120'. and yet at other times, like now, on 10m my yagi at 180' is often the
only one to hear any dx.

so the answer is: yes, you can be too high, but no, you can't get too high.

"Dave" wrote in message
. ..

tv dx is basically a line of sight vhf/uhf type
of propagation where height is everything. the higher you can go the
better

Yes, this has been my experience -- I need to get higher than my neighbor's
roof, for example.

i don't know where 10 wavelengths came from since that is actually
pretty low on the higher uhf channels!

Another Yes. At 600 MHz (near mid-band for UHF TV) 10 wavelengths is a mere
5 meters. Not much of a skyhook required to get up there!

Doubtful this applies to HF skywaves. Thanks to all..

73