RadioBanter - Max F/b and max gain at same freq.

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Yes I have those reference books but I do not have access to IRE procedings.
My quest was not an easy one and I reflected long as to why the NEC model
did not reflect an absolute zero Front to back. On reflection I realised
that a straight
element in an array is not necessarily the most efficient radiator. Then you
have the position
that a deformed radiator must have a definite coupling on other elements as
shown by Moxon
to have a resistive impedance, he used the bending of elements to pursue
this.
And there are other things to be concerned about such as element diameter
change as we move
away from the center as well as the element structure that is tubular and
not solid which would portray
a different aproach with respect to skin resistance. One thing I did look at
was the difference in F/B
when I went for maximum gain and the change that occured when I went for
maximum F/B and I was
surprised to see the F/R increase at a large rate and reach its maximum of
more than
50 percent improvement ( actually 100 % improvement for the low TOA )at the
loss of less than
one half db loss in gain because the range of maximum gain was reduced. In
retrospect this is not
surprising as the frontal lobe became larger in diameter at a lesser
percentage rate of what was
taken from the rear

Hopefully the weather will change soon so I can see exactly what is
happening with a full scale
array
Regards
Art

"Jerry Martes" wrote in message
news:Mf0Yd.43497$uc.34067@trnddc01...

Art

If your question is "is there any written work that pertains to how gain
and sidelobes are related", the answer is Yes. I dont know where back
issues of the IRE Proceedings can be found. But, the Proceedings of the
Professional Group on Antennas will have so much information on current
distribution on a planer array that you may not have enough time left to
read it all.
The current distribution across an antenna aperature has been studdied
very seriously.

I am not qualified to discuss phased arrays. I am convinced that max
gain will not be acheived with the same current distribution as for
minimum side lobes. I realize that you write only "back lobes". But,
thats a side lobe at that special angle
I am rather simple minded when it comes to phased arrays. I use
Referance Data For Radio Engineers as a referance book. It has alot of
information on phased arrays. I suspect all the information I have has
already been concidered by you.

Jerry

" wrote in
message news:2w_Xd.52445$Ze3.8223@attbi_s51...
O.K..O..K Seems like everybody has forgotton the basics of the polygon of
forces
and other uses of vector so I will go over the basics.
At the age of 14 yearsI entered the School of Engineering and Navigation
where they hashed things from first principles, Since I had little
schooling
during those war years it gave me an accelerated course on what I had
missed
during those schoolless years which meant a lot of homework and I had to
work like hell.
From the name of the school it was evident that I would get a quick
introduction
on vectors for forces and navigation
. This went as follows:
When you swim across a swimming pool then you can swim point to point.
If you swim across a river and tried to swim point to point you finish up
on the
other side but down, stream thus to get to the original point of the
endeavor you
must swim upstream. If you are a ship or a plane it is obvious that you
must have enought fuel
to get from point to point so this becomes very important.
Thus going back to the river swim you can draw a vector or line
that follows the path you took first to cross the river. Since you have
units such as time and distance
you can draw that line in scalar form. Then you add on to the tail end of
the line the journey upstream
again in scalar form which will be something less than a 90 degree angle.
If you then look back at the point that you started from it becomes
obvious that when you swim across stream
the angle you must follow is the angle which is shown from the beginning
of the triangle to
the point that you finished up. Next time you are on a plane look
downwards and pick up the flight pattern
of small private planes and you will see that their flight path is
different from the angle projected by the fuselage
All this is in accordance with Newton's law that 'every action has an
equal and opposite reaction.'
Now look below at my original post to what I said and you will see that I
applied a scalar drawing that consisted
of many scalae directions in the same way a sailing ship would do if it
had to keep changing
direction to get to shore. The first vector drawn for an element with
known phase and current was drawn
which happened to be a vertical line of known length. The next line was
then added at the end
to reflect the current and phase of the next element chosen and then onto
the next element chosen.
But this element presented a phase and current that was equal and
opposite to the one previously drawn
which meant that I was back to the tail end of my first vector chosen !
Thes two elements are termed destructive
In fact this happened several times
where vectors cancelled each other so we are just left with a singe
vector in our scalar drawing .This
meant to get back to the point of origin and remembering Newton's law
previously alluded to the scalar
drawing it represents a vector that is equal to the starting vector
drawn, THE SAME PHASE and same
CURRENT. Thus the polygon reflects an array where the phase is constant
but the currents are ADDITIVE
This represents the radiation pattern of a figure eight EXCEPT all the
radiation is now to one
side of the feed point and comprising of a single and larger circle.
All of this reflects exactly what I stated below except I assumed that
the pologon phase drawing was
already known to all, for which I apologise.
With NEC I constructed a model that closely followed this format though
the real world did not
make elements exactly equal but when I rehashed in my mind the basic
priciples the polygon aproach verified
that this aproach does give extraordinary front to back/rear figures that
gave rise to mistrust of the
softwear being used where you may remember that I commented on a model
that I made and where
the response was that the f/b was to high a point that had troubled me
for many a month.
Sorry for the long winded response which reflects what I have gone thru
with my postings which
apparently projected me as a total fool that gave rise to dirisive
comments.
Now I ask again, is there any written work that pertains to max gain and
f to b/rear being on the same frequency?
Best regards to all, no hard feelings
Art KB9MZ................XG

" wrote in
message news:dySVd.30807$r55.174@attbi_s52...
I have just come to realise that if one drew a polygon of element phases
in a array
and all elements were 180 degrees to its companion element and excluding
the
driven element, the max gain and max front to back will occur at the
SAME frequency!
Until now I was of the understanding that these two max figures could
not occur at
the same frequency. Is there anything written about this possibility?
Regards
Art

On Mon, 07 Mar 2005 01:02:18 GMT, "
wrote:
It would appear that I have come across something new.

"Kraus forgive them,
For they know not where they've polygon wrong"

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Mon, 07 Mar 2005 01:02:18 GMT, "
wrote:
It would appear that I have come across something new.

"Kraus forgive them,
For they know not where they've polygon wrong"

You said it...This is hilarious...Better than the comedy
channel.. Poor ole Art just doesn't get it...At all...
It wouldn't matter what we said, if it does not align with
his thinking, we are all ignorant, or we are trying to
crucify him to a rohn 45 tower...It doesn't matter that
the problem has nothing to do with polygons, phased arrays,
or anything else under the sun. The problem is he wants to
keep his "device" a secret, so he can claim it a new
invention. So he's afraid to give any details at all.
In doing this, he fails to realize no one has a clue to what
he is trying to describe 92% of the time...Myself, I think
this is just another round the world attempt to justify the
validity of that Rube Goldburg looking antenna he has been
trying to plug since whenever....Years it would seem...
MK

O.K. Jim you have my respect so I will go over things again.
I commented that I always thought that it was impossible to have
max gain at the same frequency that one obtained max F/B F/R.
Presumably you read that.

I then stated a theoretical situation where elements worked in pairs but
equal and opposite except
the driven element
You read that I assume
So to draw a "polygon" of the array element phases and current we start with
the driven element,
a vertical line of scalar length and then move on to add a scaler length and
phase to the end of the
director "length.
Hopefully you are still with me

But remember I stated that all other elements were equal and opposite in a
twosome form
to another element, thus even tho we we have gone thru the normal routine we
still arrive at the end
of the driven element scalar line.
Hopefully you are still with me

So to close the scalar diagram we have a line that represents an element
that is in phase
with the director i.e additive. This diagram does not show that the element
pairs are doing
nothing and therefore of no use, those elements still radiate but they
oppose each other
with the final result that to close the diagram an element is required that
has the same
phase and magnitude as the fed element
Still with me I hope

With a single dipole over ground we get a figure 8 radiation pattern
but we have just shown how an array can be theoreticaly formed that
results in a unidirectional form where one part of the figure 8 pattern
has been cancelled and at the same time we have two radiation patterns
on the same side of the feed point in additive fashion in the form of a
perfect circle which is larger than either of the circles formed in the
figure 8
pattern.

Yes a lot of steps in this thought process but stick with me

Looking at the final large circle we can say that the demise of the rear
pattern
equates with maximum gain and where the lobe width has become larger
instead of the normal narrowing effect that we get with a Yagi
Still with me?

We can also see that using such an array can avoid the manufacture of side
lobes
whether they are frontal or otherwise as our "Polygon" is symetrical where
one
made for a yagi is not such that errant reflective rays are created.

To wrap things up: the thread was created because I had created such an
array
using NEC with 300 segments per half wave which produced awesome front to
rear figures which some readers questioned the feasability. I also
questioned the results
of the model for many months ,UNTIL I came up with the cited analogy
The model matched the analogy tho the pairs of elements were not exactly
equal
but very close and the resulting pattern matched the analogy in that it
became
LARGER. With two strikes in agreement I then sort for a final crunch mode
and that was
to make what is a mechanical difficult array to build as well as expensive
for something
that still had lingering questions. The winter has been harsh but with a
little time spent
each day during the last six months I now need one half day of good weather
without wind
to place this new fangled array at the tower top and without the need of the
heavy rotor
( prop pitch) which was needed for its equivalent long boom yagi.( I do this
without help
and I am not as strong as I used to be now that I am past 70)
I don't understand the derisve comments regarding my beliefs and the
ensueing
experimentation and building except there is a prevailing thought in the
U.S.
that it is impossible to discover anything new as every thing possible was
already
known, but else where in the world the average ham still experiments to
pursue
new knoweledge.
The world is really seen as out of step with the U.S. in more that one way
and this
thread portrays just one more thing to add to the list.
Regards
Art...... KB9MZ,,,,,, XG

\
I then illustrated where such an array could be drawn polygon fashion
You read that I assume
"Jim Kelley" wrote in message
...

wrote:

Yes I am aware of that and I expressed amazement at your lack of
knoweledge
as expressed in this thread. At the same time I see you are referring to
stuff
that you wrote when you were younger and things change as you get older.
A case in point is the ELZEC program which frankly does not match up with
todays technology or competitive programs yet maintains a high price
presumably based on your past achievements.
But when you express your knoweledge as you did this week
and showed complete lack of knoweledge regarding the subject at hand then
it may well be a sign of the times as it were and you resorted to attack,
not the
underpinnings of what I stated but me as an individual. If you were a
profesional
you would have attacked the polygon example given at the onset of this
thread
but then you expressed lack of knoweledge of the subject and I commended
you for that but the passing of time places no mercy on any of us
mortals as
we age despite our personally perceived station in life.

What you described would be at best be described in contemporary venacular
as a polyline. As has been explained, a polygon is a closed shape. A
polyline could form a polygon in the special case where the phase angles
sum to 360 and the line segments are of proper length and in a particular
order. I think most of us here know that Roy of all people has no trouble
at all with such a concept. I also have been following the thread, and
what you didn't describe is how any of that relates to the antenna
question you asked. Hence the mix-up.

73, ac6xg

On Thu, 10 Mar 2005 22:56:37 GMT, "
wrote:

Oh come on Wes look at your last posting where you poked fun at the idea of
a polygon phasor array. And look at the other postings where it was obvious
that many were not familiar with the same and needed more direction. Look at
Roy,
he admitted he knows nothing about the subject

He did no such thing. Not only are you having difficulty expressing
yourself, you have similar difficulty understanding what others are
trying to tell you. I'm not trying to be cruel or harsh, but that's
just the way it is.

which when he next argues with the like of Cecil and others I will now have
to think twice instead of accepting his typical
riposte that he supplies. But I give Roy credit for being honest in the face
of personal embarassment regarding his lack of knoweledge
You say it was not necesary to provide a long convoluted pseudo treatise on
vectors but many asked for it and you made a joke of the idea,
Regarding front to rear occuring at the same frequency. An operator wants as
much gain as possible when communicating
so he does not need to resort to more power than needed. For best
communication it is nice to block of interference to the rear and thus he
needs best front to rear at the frequency of communication even tho it is of
interest that he had better rejection at a lower frequency. The fact of the
matter is that it is not the frequency being used, he has to live with a
lesser value of rejection, your opinion may well be different.

So if I understand you correctly ( a *really* dubious proposition) I
would have much better success with my 20 meter antenna if I embraced
your philosophy. My current antenna is of my design, a three-element
monoband Yagi-Uda parasitic array. You can see it in the picture on
qrz.com. It is an honest to goodness actual antenna. I have 310
countries confirmed on 20 meters most of them (The hard ones) worked
with this antenna. All at the "too-low" height (according to you) of
45' above ground. I would be delighted to send you an EZNEC,
Multinec, or NEC file that describes the antenna. The model accounts
for boom to mast connection, element taper, etc. (per Leeson,
"Physical Design of Yagi Antennas."), includes the stub matching feed
system and appears to accurately describe the antenna to the best of
my limited capability to measure it.

Over the band of interest, 14.0 to 14.25 MHz., the modeled free-space
FB exceeds 20 dB and the gain varies from ~ 7.9 to 8.15 dBi. The FB
peaks at ~ 14.12 MHz and the gain is maximum at 8.15 dBi at 14.25 MHz.
Pray tell, what operational advantage am I giving up because the gain
at 14.12 MHz (the FB peak) is *only* about 8.0 dBi instead of 8.15
dBi?

Now you also remarked that you do not want explanations, just the meat. I
gave what you call a "treatise" that explained the theoretical
underpinnings of what I have stated. It would be unwise at this point to
declare success without not only having a NEC model to confirm it but also a
20 meter antenna and not say a 144 meg equivalent. Today we had snow, wind
and rain so I could not complete the job.If by chance the antenna gives a
third aproval i.e.Nec model then polygon discussion plus the antenna then I
will forward it to RADCOM for peer review. It is at that time you can vent
your displeasure that you rejected my offer to share the actual mathematical
and physical findings. If you were looking for a way to undermine what I had
stated then my " treatise" now arms you with the knoweledge to disprove what
I have stated as it is one factor that convinces me of my origonal findings.
If you need more information regarding vectors I will be happy to aid you in
your quest

No, I don't needed any more of your help with vectors. I wish you
every success with your RADCOM paper.