"Denny" wrote in message
oups.com...
You are right... You are so far ahead of this group that we can not
even comprehend the question...


Denny,

This is all apparently intended as a guessing game, as art has given us just one
single parameter of the exercise --- he wants to communicate with the UK in the
winter.

From where?

At what time(s) of day?

On what QRG(s)?

What construction constraints? (budget, zoning, etc.)

73, de Hans, K0HB
--
Homepage:
http://www.home.earthlink.net/~k0hb
Member:
ARRL http://www.arrl.org
SOC http://www.qsl.net/soc
VWOA http://www.vwoa.org
A-1 Operator Club http://www.arrl.org/awards/a1-op/
TCDXA http://www.tcdxa.org
MWA http://www.w0aa.org
TCFMC http://www.tcfmc.org
FISTS http://www.fists.org
LVDXA http://www.upstel.net/borken/lvdxa.htm
NCI http://www.nocode.org

Hans, you are so full of it, like Andy Capp waving his hands around in
the air to
vent his fraustration. Go back to the initial posting and what it says.
All of your comments refer to side issues brought up that are not
relavent to the initial question
wthich also is not a guessing game to those skilled in the art
Ar





KØHB wrote:
"Denny" wrote in message
oups.com...
You are right... You are so far ahead of this group that we can not
even comprehend the question...


Denny,

This is all apparently intended as a guessing game, as art has given us just one
single parameter of the exercise --- he wants to communicate with the UK in the
winter.

From where?

At what time(s) of day?

On what QRG(s)?

What construction constraints? (budget, zoning, etc.)

73, de Hans, K0HB
--
Homepage:
http://www.home.earthlink.net/~k0hb
Member:
ARRL http://www.arrl.org
SOC http://www.qsl.net/soc
VWOA http://www.vwoa.org
A-1 Operator Club http://www.arrl.org/awards/a1-op/
TCDXA http://www.tcdxa.org
MWA http://www.w0aa.org
TCFMC http://www.tcfmc.org
FISTS http://www.fists.org
LVDXA http://www.upstel.net/borken/lvdxa.htm
NCI http://www.nocode.org

On Fri, 22 Sep 2006 03:32:13 -0700, Roy Lewallen
wrote:

"efficiency" of the best HF antenna is better than
0.001% by this criterion.

Hi Roy,

Not far off.

If absolutely EVERYONE (presuming 6 billion of us) on the planet got
art's signal at S9 from a 100W transmission, that would only be 300 mW
captured (0.3% efficient).

I suppose the 99.7W lost would contribute to Intergalactic Warming
(which would be 99.7% efficient). However, HF temperature is for all
practicable purposes indistinguishable from absolute Zero.

73's
Richard Clark, KB7QHC

Neat
Art
Richard Clark wrote:
On Fri, 22 Sep 2006 03:32:13 -0700, Roy Lewallen
wrote:

"efficiency" of the best HF antenna is better than
0.001% by this criterion.

Hi Roy,

Not far off.

If absolutely EVERYONE (presuming 6 billion of us) on the planet got
art's signal at S9 from a 100W transmission, that would only be 300 mW
captured (0.3% efficient).

I suppose the 99.7W lost would contribute to Intergalactic Warming
(which would be 99.7% efficient). However, HF temperature is for all
practicable purposes indistinguishable from absolute Zero.

73's
Richard Clark, KB7QHC

Dave wrote:
"art" wrote in message
ups.com...

Richard Clark wrote:
On 21 Sep 2006 19:09:38 -0700, "art" wrote:

Notwithstanding that the
upper half of the major lobe serves no usefull purpose to what the
antenna is required for there is a mass of radiation in many directions
and levels that have no connection to the required purpose of the
antenna, thus we have a lot of wasted radiation that if we harness it
so that it is used for the antennas primary use the efficiency of the
antenna would increase immensly.

Hi Art,

The classic solution is to stack yagis vertically. This draws down
the higher radiation lobes and puts their gain in the forward
direction.

Well you are getting closer to the question at hand. You have now
doubled the
power input but only slightly gained directionality(2db) efficiency I
would also suspect that you have flattened the lower lobe only into a
pancake shape. But again I go back to the desirable radiation which can
be said in this case to be the lower half of the major lobes half power
envelope which for a directional radiated array is very small compared
to the total radiated field.True propagation can play games but the
ARRL
give the average arrival angles over a 11 year period so it is not a
hopeless task to get a ball park figure regarding usefull radiation
knowing where the target is
I suppose I could make a model and slice out the half power lobe
portion and compare the two volumes for myself, I just thought that it
had already been looked at
Oh well back to the drawing board
Art

what you are missing is the variability in that arrival angle. if you are
interested in a specific path you must be able to receive all the possible
arrival angles, which with yagi's requires mounting several of them at
different heights. for instance consider a path from w1 to western europe
at the sunspot peak on 10m... it is not uncommon for the band to open at a
very low angle, say where a single yagi at 120' is the best antenna, then as
the day progresses the angle increases so much that the 120' antenna is
almost worthless but one at only 30' is working great. if you put
everything into getting that 10-12 degree angle you lose out by mid morning
when the arrival angle is up to 30 degrees or more...


David that is not absolutely correct, we are talking about a single
point to point communication where the arrival angle is below 10
degrees. If the angle of arrival is above that then it is created by
unusual propagation or deflection of radiation path. For a given
distance one can say that the communication energy level is comensurate
with the number of skips taken where a point is reached when the number
of skips controls the amount of energy left at the communication
distance. Thus the east may hear the west coast talking to Europe where
they cannot hear the transmitting station because of the excessive
number of hops. Remember, I am talking about point to point
communication
which largely defined by the number of skips taken which is why dipole
to dipole transmissions are pushed aside for those desiring DX contacts
tho I am sure you are not advocating dipoles for DX.



but at the same time
that top antenna may be working great into siberia!

what you are looking for is not normally called 'efficiency', but
'directivity'. unfortunately horizontally polarized yagi's vertical
radiation pattern is very dependent on height

do you really mean "vertical: radiation pattern?

and the terrain so increasing
the directivity is seen mostly in the width of the pattern. and as noted
above, controlling the vertical pattern is normally done by changing the
antenna height, usually by stacking multiple antennas on the tower and
selecting them one at a time or in combinations to give the desired vertical
coverage.

No... stacking is used purely to provide a vector to combat the earths
magnetic field
which affects all radiation directional patterns not only a vertical
pattern

There have been some experiments with variable phasing of stacked
yagis, but it is not a common capability in amateur installations.

Exactly since these methods provide a vectoir to counteract the
terrains magnetic field
unfortunately this requires extra power supply points where the desire
is for just one.
Art

Roy Lewallen wrote:
I'm not sure I understand the question, but a large fraction of the
total power is typically in the main lobe of a Yagi. You won't increase
the power in the main lobe significantly by reducing or eliminating
other lobes, because there just isn't much power there.

Roy you know better than that ! gain is a binomial function with
respect
to the forward radiation at the point of initiation. It does nothing to
salvalge energy
expended in the reaward direction, to do that another vector is
required that cannot be produced by a planar array. As far as traps
being lossy as if they get hot or something that is also untrue, what
you are seeing is a radiation field created by the trap that is in
opposition to that created on the element i.e. a field that is 180
degrees out of phase



If you want more
power in a narrower range of directions, you need more directionality,
which means a longer Yagi, stacked Yagis, or some other type of antenna
which will probably be larger. The methodology for and tradeoffs
involved in increasing directionality are well known.

And because Yagis
(ones not having lossy traps or loading components) are very efficient,
directionality and gain are inextricably linked. Again I do not agree that Yagis are efficient

Art

Roy Lewallen, W7EL

art wrote:
Roy Lewallen wrote:
I'm not sure I understand the question, but a large fraction of the
total power is typically in the main lobe of a Yagi. You won't increase
the power in the main lobe significantly by reducing or eliminating
other lobes, because there just isn't much power there.

Roy you know better than that ! gain is a binomial function with
respect
to the forward radiation at the point of initiation. It does nothing to
salvalge energy
expended in the reaward direction, to do that another vector is
required that cannot be produced by a planar array.

Sorry, I can't make the slightest amount of sense out of this.

As far as traps
being lossy as if they get hot or something that is also untrue, what
you are seeing is a radiation field created by the trap that is in
opposition to that created on the element i.e. a field that is 180
degrees out of phase

Egad. There's no point in my wasting time by attempting to contribute
further to this. I'll leave you to your alternate reality.

Roy Lewallen, W7EL

Roy Lewallen wrote:
Egad. There's no point in my wasting time by attempting to contribute
further to this. I'll leave you to your alternate reality.

Now you know how I felt after your posting questioning
(denying?) the existence of reflected energy.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Roy Lewallen wrote:
Egad. There's no point in my wasting time by attempting to contribute
further to this. I'll leave you to your alternate reality.

Now you know how I felt after your posting questioning
(denying?) the existence of reflected energy.
--
73, Cecil http://www.w5dxp.com
Cecil as I said in another posting it takes a generation for change
to be accepted. Until then the common response is I don't understand
because their education followed a well trodden path where memory was
the accepted
path to success. Unfortunately this allowed things outside the trodden
path to be bypassed as the great unknown. Note that Roy did not give a
sensible response only theatrics to either of the things I pointed out
because conflict often prevents reasonable thought with an open mind.
If theire was no conflict in his mind he would have trotted out how the
radiation to the front is enhanced by radiation to the rear that is if
he had the answer.......but he does not . As far as reflections go that
was not part of his education itiniary so he will go with the flow. Roy
is an expert in his particular field because he has a good memory take
him outside that boundary and he becomes a different person and pouts
Fortunately he said he is not going to bother me any more so that it is
my hand
hand ithat is lifted .Shame that Reg is not around to witness his feux
par
Art

On 21 Sep 2006 17:05:44 -0700, "art" wrote:

Hi Art,

To close this out, we have discovered through the various
correspondents that:

When one looks at a.radiating array pattern one can see that the yagi
is very inefficient.

Is false. That much is clear through evidence, no theory necessary.

Does anybody know of the relative volume
contained in the main radiation lobe versus the total volume of the
entire pattern?

Yes, someone does. It was pointed out quite clearly that ALL the gain
from sidelobe or back lobe could not be assembled into very much
constructive gain. Economists call this the law of diminishing
return.

A casual look at a yagi radiation pattern would suggest
that it is less than 50% efficient at best

Is false. One can certainly contrive for abysmal efficiency (you use
mylar and bamboo in place of tubing don't you?); but that does not
make the range of yagis fall into disrepute through aberrations of one
designer.

especially when considering

Is false - there are no externalities, except local ground loss, to an
antenna (and that exception is because ground is part of the radiating
system).

DX work
where even the main lobe is less than 50% efficient when looking at
available
signal paths beyond 4000 miles which are somewhat below 12 degrees and
where the main lobe itself is centered between 13 and 14 degrees with
an
average amateur antennah

You don't have any choice in the matter. No element pair is ever
going to offer better. No single yagi is going to draw the peak
launch angle down to the elevations I've already identified. A stack
of yagis is hardly likely either.

The long and short of it is that you are facing 0.001% "efficiency"
without any probable method to even budge it up to 0.0015%.

Creationist scienze might help tho'.

73's
Richard Clark, KB7QHC