"Wes Stewart" wrote in message
...
On Sat, 19 Mar 2005 19:36:35 GMT, "
wrote:
"Wes Stewart" wrote in message
. ..
On Thu, 17 Mar 2005 10:54:50 -0800, Roy Lewallen
wrote:
Actually, it is possible to lower the takeoff angle (the elevation angle
at which the pattern is maximum) without changing the antenna height.
The method is to narrow the free-space elevation radiation pattern. For
example, modify the EZNEC example file W8JK.ez by changing the height (Z
coordinates) to 0.5 wavelength. The takeoff angle is 25 degrees. Delete
one of the elements to make a dipole and note that the dipole's takeoff
angle is 28 degrees. The lowering is due to the substantially greater
elevation directivity of the W8JK. There aren't too many modestly sized
horizontal arrays that have enough elevation directivity to make much of
a difference in takeoff angle, however, so the difference is generally
small at best. It's also interesting to note that the takeoff angle of
this dipole over real ground is 2 degrees lower than the takeoff angle
of the dipole over perfect ground.
All true. I see my response was too encompassing. What I was trying
to refer to was Art's "magic" design.
To wit: "Would hams have an interest in a two element 20 M antenna
that have (sic) lower TOA than the norm, say 9 degrees instead of the
normal 14 degrees?"
I can't imagine anything that will make a 2 (or any other number)top hat
element horizontal antenna of any configuration have a TOA of 9
degrees other than placing the array center at a height of ~105' above
real ground at 14 MHz.
Note this is not a *direct quote*. I did not say "top hat" in the
original post.
I don't remember the two element bit and I also stated it was NOT a yagi
design.
Let me refresh your memory:
On Wed, 16 Mar 2005 02:57:31 GMT, "
wrote:
snipots !
Would hams have an interest in a two element 20 M antenna that have
lower TOA than the norm, say 9 degrees instead of the normal 14
degrees?
I think I can quickly put one together for the week end while putting
the present assembly aside.
Regards
Art"
End quote
Yes I remember it now and yes I think I could put one together
...........so what, nothing special in that!
Doesn't the foregoing *exact* quote say, "...two element 20 M
antenna....?"
You mentioned horiuzontal (sic) antenna which suggests a yagi (sic) design
unless you
intended
horizontal "polarisation".
Okay polarize it any way you want, and I don't see where I mentioned
Yagi at all.
No, I am making the point regarding the "horizontal antenna" comment
I would not say my antenna was "horizontal" per se ,if it were then
reference
to a yagi design could be used at a stretch for any "horizontal antenna'
that
consists of a boom
Roy, same as I, is pointing out the number of
incorrect statements that you have made and you are now adding to them.
Roy made a valid point. You on the other hand are full of it.
Roy just reiterated what I said previously where the bottom contour of the
main lobe
can remain the same for many antennas which have different TOA and it is
this
contour that is importantThus TOA can be designed for the frequency of
choice. Period!
And try as you might you just can't change this fact.
To help you out I will stop posting on this thread to save you any further
embarrasment (sic), that way you will not need to admit to anymore (sic)
errors.
When you can show me an error, I will admit to it. So far there's
nothing to admit to. But I can understand your desire to drop out.
Pity you didn't define what you meant with respect to antenna height i.e.
feed point height, top hat height, a higher unfed antenna height and so
on.
I said, "array center." If you want to vertically polarize it you
might make it at ~70 to 80' with a pair of collinear dipoles if you
can figure out a practical way to feed it. That would give a whopping
4 - 5 dBi at 9 degrees, where my Yagi design at 70' has 12 dBi at 9
degrees even though the max gain is at 13 degrees. (One of the points
Roy was making)
Array center means what? The center of a loop, the center of an inverted
vee,
the center of.. well no point in carrying on with the "Array center"
You're claiming some magic design that will lower the "TOA"
significantly, from the "norm" (from whatever hat that came from) of
14 to 9 degrees, without increasing the antenna height. I'm
suggesting that you can't do it. Prove me wrong - wait a minute; you
already confessed that you couldn't.
Lets get back to facts as stated in this thread and not innuendo.
My tower is a fold over, the antenna
is such that the method of coupling is unique and is the foundation of the
design
(I know groans regarding my fascination with CLOSE coupling.) The single
feed point of the antenna
assembly is at approx 65 feet. It is capable of placing best F/B at the SAME
frequency as
best gain.The impedance level is not controlled ( low impedance) as with a
high gain yagi design.
and its performance can be compared to a 1WL boom Yagi design antenna . Yes,
I can use a
commercial rotor instead of my heavy prop pitch rotor.
I also have said that it could not compete with the simplicity of the YAGI
mechanical
design aproach.
All the above I have mentioned one way or another together with the fact
that the main lobe
has a larger beam width than the yagi design which can be important when the
gain of the antenna
narrows the beam. And lastly, I pointed out the basic theory using the
vector diagram approach
when idealistically where radiation at the rear is removed the main lobe is
a pure circle and not elongated
as a YAGI design would provide and where one can surmise that forward side
lobes would not be
generated. Oooops forgot.it can be used as a multi bander!
Now those are the facts that I have presented. Others have twisted the above
to suggest something else
or additions. For me what I have presented is just a pushing out of the
envelope antenna knoweledge
and to show that no matter what, all is not known about antennas or R.F.
radiation And as with all new things
that come forward all will say that they knew that all the time but just
didn't get around to it,
just like many say when they see the winning lotto number.
I will not offer any more facts since the intent of many is to just promote
arguments, play games
and certainly not to discuss technicalities that suggest all is false and
point out why with logic.
Think about the initial thread heading and then note to yourself how
individuals responded
in answer to the heading. Yup all were different but all with the diversion
aproach.
And you of all people scolded me for presenting a "precis" regarding vector
analysis because many
stated they had no understanding of its use and where the experts stayed
silent because they failed to
remember 101 and where you miraculously remembered it after my post. Even
then you failed to point
out any points that made it a bogus aproach.
I would say that the average antenna at a height of 1 WL has a elevation
angle
(TOA ) of around 14 degrees . Read the Antenna book of the ARRL!
Adding ambiguety (sic) just leads to confusion for everybody.
This coming from an expert at bafflegab.
And speaking of bagglegab...
Frankly you are looking more like Richard every day with your leaning on
emotions instead instead of technical matters pertaining to the thread
with
the
assumption that all must be placed before you for judgement as you are the
leading analysts in antenna design.
Actually with respect to this thread both of you are showing that you are
wearing no clothes tho Richard could well be wearing Shakespeare hose
of a see thru nature that he wears around his abode.
See you on another thread perhaps.
Regards
Art KB9MZ....XG
You got me to come back Wes to this thread but no more.
Have at it You are now free to wave your arms around like
Andy Capp knowing that all you say will not be refuted
regardles of the clothing that you wear
Regards
Art KB9MZ...XG
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