"Roy Lewallen" wrote in message
...
"Takeoff angle" can have two meanings. The first, and really a misuse of
the term, is the one used by antenna modeling programs such as EZNEC. It
means the elevation angle at which an antenna's radiation is maximum. This
is a property of the antenna and its local environment (particularly the
height above ground for horizontal antennas, and local ground quality for
vertical antennas).

And I thank very much for the above statement to which I fully agree.
But later you turn away from that statement with respect to the
propagation conditions do you not?


The second meaning is the elevation angle at which propagation occurs.
This is dictated mainly by the propagation path -- the distance and the
effective height of the ionosphere. The antenna pattern can play a role
only when more than one path is possible, for example single and double
hop, by modifying the amount which propagates by each path.he environment

Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max radiation
which directly controls the main lobe dimension both in width and height.
I model an antenna array such that it emulates in a way a "stacked"
array where as low as a 9/10 degree TOA. The 3 db gain window is broader in
width and narrower
in height than say the normal array. It is this "TOA" that determines what
window we have and
where it hits the ionesphere which thus determines its point of arrival on
the earths surface
Not propagation which is the "environment" of all antenners in the vicinity
and the same
for all antennas at a particular time.
The ARRL clearly shows that it is the TOA that determines the range as it
were of one antenna
comparered to the others with different TOA.. For the life of me I cannot
concurr with the statement
as stated.
I would also add that a antenna with a lower TOA invarably means a thinner
lobe of radiation
as well as a lower 3dB window and in a few cases the underside contour of
the main lobe can
be lower than one of equivalent gain. I use the term TOA as being the line
of maximum gain
In no way do I infer that we have laser type radiation as compared with a
flashlight style radiation


The "takeoff
angle" of the first meaning (angle at which the radiaion is maximum) isn't
a particularly useful measure of and antenna's performance, and it
certainly doesn't determine the real "takeoff angle" of the second meaning
(angle at which propagation occurs).

Then it is here that that we are entangled. I agree the envionment
can affect or deflect radiation, whether it be a mountain face or the
down slope of a mountain, but I do not see how existing propagation
can mold the direction of such radiation, and possibly it is here
that my learning curve can be bettered . To me, propagation affects
first come into being when the ionesphere is able to" turn" or "deflect"
radiation according to the relative angle of impact of that which it turns
and not before. ( when all is said and done this is the crux of the debate)


Art has used "takeoff angle" of the first meaning liberally in his
writings, often with the added and incorrect implication that all the
radiation from an antenna occurs at its "takeoff angle", with none at
other elevation angles. So his confusion about Richard's statement (which
correctly used "takeoff angle" in the second sense) is understandable.

No,
That is not true. My experimentation is aimed at arriving at a low
TOA for an antenna. The reason is two fold

"1" A lower TOA usually means that the upper half of the main lobe is
reduced
and the lower half of the lobe is not reduced. Thus radiation is
contained
within an angle of radiation that is usefull and not wasted as it is with an
antenna of a higher
TOA.

"2" When the attributes of "1" above are achieved it is then possible to
LOWER the underside
of the main lobe contour where one can communicate at lower angles with a
single feed array
and obtain the advantages of multi stacked arrays with multi feed point.

Is this the error of my ways where any change I make to an antennas pattern
is rendered of no use because I must first find a way to manipulate
propagation
where all the action is really at?

I also want to make it clear that I appreciate your post which I see as an
attempt to clarify matters
that are presently being discussed ie.It is propagation and not the antenna
that determines the
TOA. Or "antenna pattern is determined by propagation" so that we don't
get hung up
on the term TOA
Very best regards
Art


Roy Lewallen, W7EL

wrote:
Richard,
You are at it again, avoiding the supply of corroberation to what you
say is true.
Stick to the basic statement that you made, which from their silence, the
gurus concur
with.
Your statement was that:
propagation is what determines TOA
and I ask for confirmation of the correctness of that
statement from you in the nature of some written text.
The gurus obviously accept your statement as fact, but I do not.
Usually you refer to a text to back up your statement ,but this time you
haven't, winging it
and relying solely on the fact that the gurus agree with you.
Surely you or some guru can come up
with a written text that states that propagation is what determine TOA.!
That is what this group is all about where gurus debunk the untruths
and supply the real truths and not to let old wives tale dominate.
You also stated that you made the ":assumption" presumably
based on the "facts" stated above that the Curtain could be considered as
similar to the dipole
since propagation determines that they are the same. This is total junk
,in its entirety,
unless you or the gurus can come up with a written text that confirmes
their positions.
Art

wrote:
. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max radiation
which directly controls the main lobe dimension both in width and height.

And, as I've said quite a few times in one way or another, it's largely
a waste of time.

I model an antenna array such that it emulates in a way a "stacked"
array where as low as a 9/10 degree TOA. The 3 db gain window is broader in
width and narrower
in height than say the normal array. It is this "TOA" that determines what
window we have and
where it hits the ionesphere which thus determines its point of arrival on
the earths surface

That's absolutely incorrect. All antennas radiate at all angles. The
ionosphere doesn't know or care at what angle your antenna is radiating
the most -- propagation will occur at the angle favored by the
ionosphere at the time. Your antenna's pattern doesn't dictate the
geometry of the path.

Not propagation which is the "environment" of all antenners in the vicinity
and the same
for all antennas at a particular time.
The ARRL clearly shows that it is the TOA that determines the range as it
were of one antenna
comparered to the others with different TOA.. For the life of me I cannot
concurr with the statement
as stated.

By speaking of "environment" I was not including propagation, and in
conforming to traditional usage, I also don't include propagation when
speaking of antenna patterns. An antenna pattern is a polar plot of the
field intensity of the antenna at a distant point, but with the
assumption that the propagation to all points is lossless. The actual
signal received at a distant point requires the inclusion of propagation
effects. The pattern is one element in the equation, but only one.

. . .


Is this the error of my ways where any change I make to an antennas pattern
is rendered of no use because I must first find a way to manipulate
propagation
where all the action is really at?
. . .

Close. Sometimes two or more propagation modes are possible, such as
single and double hop. From here to say, New York, I might have single
hop at 3 degrees and double hop at 12. (Please forgive me if those
particular propagation angles can't really occur at the same time, but
they're in the ballpark.) It doesn't matter one iota what the angle of
maximum radiation from my antenna is. All that matters is the gain or
field strength at elevation angles of 3 and 12 degrees. All the rest of
the radiation will go some place besides New York. As a general rule, I
can get a stronger signal to New York with X dBi at 3 degrees than the
same gain at 12, because the single hop path loss is usually less. So it
might pay me to maximize my gain at that angle at the expense of 12
degrees. On the other hand, the other station's antenna pattern is just
as important -- if it has a lot more gain at 12 degrees than 3, he might
not hear me if I put out most of my energy at 3 rather than 12. But in
any case, it doesn't matter how much I'm radiating at 1, 5, 7, or 15
degrees, or what my antenna's maximum angle is. All that counts is how
much I'm radiating at 3 or 12 degrees. Other than manipulating your
antenna to radiate more or less at those two angles, you don't get to
"manipulate propagation" to support other angles at a given time,
frequency, and path. You're stuck with those until the ionosphere
changes. Knowledgeable DXers (which I'm not) spend a lot of time working
out what the angles will be for propagation to various target locations,
and how to design, build, and switch antennas to maximize the amount of
radiation at those angles.


I also want to make it clear that I appreciate your post which I see as an
attempt to clarify matters
that are presently being discussed ie.It is propagation and not the antenna
that determines the
TOA. Or "antenna pattern is determined by propagation" so that we don't
get hung up
on the term TOA

No, antenna pattern isn't determined by propagation. The signal strength
at the other end of the path is determined by the gains of both the
transmit and receive antennas at the elevation angle of propagation, and
the loss along the path. Period. Notice that "takeoff angle" and
"pattern" didn't appear in that sentence. And you don't get to choose
the angle of propagation (unless more than one are supported at a given
time, which is only sometimes true, and then you can only choose between
the supported angles).

I suggest downloading the excellent, free, and easy to use propagation
software by Shel Shallon, W6EL, http://www.qsl.net/w6elprop/. In a few
minutes, you'll be able to see what angles are supported at a given time
and frequency for a given path.

Roy Lewallen, W7EL

"Roy Lewallen" wrote in message
...
wrote:
. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max
radiation
which directly controls the main lobe dimension both in width and height.

And, as I've said quite a few times in one way or another, it's largely a
waste of time.

Why? A single word question
On what authority do you base that statement on?



I model an antenna array such that it emulates in a way a "stacked"
array where as low as a 9/10 degree TOA. The 3 db gain window is broader
in width and narrower
in height than say the normal array. It is this "TOA" that determines
what window we have and
where it hits the ionesphere which thus determines its point of arrival
on the earths surface

That's absolutely incorrect. All antennas radiate at all angles. The
ionosphere doesn't know or care at what angle your antenna is radiating
the most -- propagation will occur at the angle favored by the ionosphere
at the time. Your antenna's pattern doesn't dictate the geometry of the
path.

Not propagation which is the "environment" of all antenners in the
vicinity and the same
for all antennas at a particular time.
The ARRL clearly shows that it is the TOA that determines the range as it
were of one antenna
comparered to the others with different TOA.. For the life of me I cannot
concurr with the statement
as stated.

By speaking of "environment" I was not including propagation, and in
conforming to traditional usage, I also don't include propagation when
speaking of antenna patterns. An antenna pattern is a polar plot of the
field intensity of the antenna at a distant point, but with the assumption
that the propagation to all points is lossless. The actual signal received
at a distant point requires the inclusion of propagation effects. The
pattern is one element in the equation, but only one.

. . .


Is this the error of my ways where any change I make to an antennas
pattern
is rendered of no use because I must first find a way to manipulate
propagation
where all the action is really at?
. . .

Close. Sometimes two or more propagation modes are possible, such as
single and double hop. From here to say, New York, I might have single hop
at 3 degrees and double hop at 12. (Please forgive me if those particular
propagation angles can't really occur at the same time, but they're in the
ballpark.) It doesn't matter one iota what the angle of maximum radiation
from my antenna is. All that matters is the gain or field strength at
elevation angles of 3 and 12 degrees. All the rest of the radiation will
go some place besides New York. As a general rule, I can get a stronger
signal to New York with X dBi at 3 degrees than the same gain at 12,
because the single hop path loss is usually less. So it might pay me to
maximize my gain at that angle at the expense of 12 degrees. On the other
hand, the other station's antenna pattern is just as important -- if it
has a lot more gain at 12 degrees than 3, he might not hear me if I put
out most of my energy at 3 rather than 12. But in any case, it doesn't
matter how much I'm radiating at 1, 5, 7, or 15 degrees, or what my
antenna's maximum angle is. All that counts is how much I'm radiating at 3
or 12 degrees. Other than manipulating your antenna to radiate more or
less at those two angles, you don't get to "manipulate propagation" to
support other angles at a given time, frequency, and path. You're stuck
with those until the ionosphere changes. Knowledgeable DXers (which I'm
not) spend a lot of time working out what the angles will be for
propagation to various target locations, and how to design, build, and
switch antennas to maximize the amount of radiation at those angles.


I also want to make it clear that I appreciate your post which I see as
an attempt to clarify matters
that are presently being discussed ie.It is propagation and not the
antenna that determines the
TOA. Or "antenna pattern is determined by propagation" so that we
don't get hung up
on the term TOA

No, antenna pattern isn't determined by propagation.

Whoopee

The signal strength
at the other end of the path is determined by the gains of both the
transmit and receive antennas at the elevation angle of propagation, and
the loss along the path. Period. Notice that "takeoff angle" and "pattern"
didn't appear in that sentence. And you don't get to choose the angle of
propagation (unless more than one are supported at a given time, which is
only sometimes true, and then you can only choose between the supported
angles).

It is up to the user to design the antenna with the pattern of choice
and that is what I did. And you can do it to since you are familiar
with antenna programs. You just have to point the initial program so it
is able to spot what dimensions are required to produce the required
pattern.
Roy please go back to the top and answer that simple one word question
and let it all hang out
Best regards
Art


I suggest downloading the excellent, free, and easy to use propagation
software by Shel Shallon, W6EL, http://www.qsl.net/w6elprop/. In a few
minutes, you'll be able to see what angles are supported at a given time
and frequency for a given path.

Roy Lewallen, W7EL

wrote:
"Roy Lewallen" wrote in message
...

wrote:

. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max
radiation
which directly controls the main lobe dimension both in width and height.

And, as I've said quite a few times in one way or another, it's largely a
waste of time.


Why? A single word question
On what authority do you base that statement on?

Because "takeoff angle" as you use the term does not bear a direct
relationship to the ability to communicate.

Roy Lewallen, W7EL

On Tue, 26 Apr 2005 19:15:44 -0700, Roy Lewallen
wrote:

wrote:
"Roy Lewallen" wrote in message
...

wrote:

. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max
radiation
which directly controls the main lobe dimension both in width and height.

And, as I've said quite a few times in one way or another, it's largely a
waste of time.


Why? A single word question
On what authority do you base that statement on?

Because "takeoff angle" as you use the term does not bear a direct
relationship to the ability to communicate.

Right on.

Let's look at it this way. If I have an antenna with a "pencil beam"
and it's pointing at 90 degree azimuth and the station I want to
communicate with is at 0 degrees, I don't know of anyone who would say
that this is an optimum situation.

Yet, many (okay, one) would say that an antenna with (pardon me) a
"take off angle" of 3 degrees is *always* superior to one with a TOA
of 20 degrees, notwithstanding the fact that the desired station's
signal is maximum at 20 degrees.

This is like saying that I have room for a rhombic pointed at Asia so
I'm going to work my ass off optimizing it when all of the stations I
want to work are in Europe.

Why is this so? I'm completely baffled.

"Roy Lewallen" wrote in message
...
wrote:
"Roy Lewallen" wrote in message
...

wrote:

. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max
radiation
which directly controls the main lobe dimension both in width and
height.

And, as I've said quite a few times in one way or another, it's largely a
waste of time.


Why? A single word question
On what authority do you base that statement on?

Because "takeoff angle" as you use the term does not bear a direct
relationship to the ability to communicate.

O.K. Roy if you are going to let this discussion revolve solely around the
term
of TOA which is a datum line around which the main lobe evolves,, A term you
have voiced
opposition to over the years and which you personally use in your own
antenna program design
then you will be succesfull in any debate regarding antennas. I have stated
many times that the
elevation angle denotes the line of maximum gain and the lobe that surrounds
this angle denotes
the area of communication ability represented by the oft used term of the 3
dB window.
You are refusing to accept the use of this term because of personal
emotional reasons,
that you only use the term under protest because of commercial reasons and
now as a basis for rejecting.
new knoweledge supplied by computor programs.,. presumably by clinging to
"all is known" mantra
I will never persuade you to view this thread with an open mind.
You have stated that TOA as I describe the term does not bear a direct
"relationship "
to the ability to communicate which obviously must relate to a part of a
post where you
envision that you have accomplished a "gottcha".
One person stated that everybody knows that I am right which I question,
especially
since you have now come forward with contrary thoughts.
Roy, there can be no debate if one must always accept
all your statements in Pope like fashion that excludes discussion.
Best regards
Art
Roy Lewallen, W7EL

wrote:
. . .
You are refusing to accept the use of this term because of personal
emotional reasons,
that you only use the term under protest because of commercial reasons and
now as a basis for rejecting.
new knoweledge supplied by computor programs.,. presumably by clinging to
"all is known" mantra
I will never persuade you to view this thread with an open mind.

. . .

Roy, there can be no debate if one must always accept
all your statements in Pope like fashion that excludes discussion.
Best regards

This sort of response doesn't constitute a debate, and it's nothing I
see any need or desire to respond to.

Roy Lewallen, W7EL

On Wed, 27 Apr 2005 03:11:34 GMT, "
wrote:

a basis for rejecting.
new knoweledge supplied by computor programs

Hi Art,

More baloney cut thick. You have NOWHERE offered any discussion of
ANY new knoweledge (sic); but you hug such manufactured sentiments
like an emotional life preserver.

You rctleeny challngeed Roy for his athortuy. You wloud do well to
leran spllenig bfoere ripeteang that aigan.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Wed, 27 Apr 2005 03:11:34 GMT, "
wrote:


a basis for rejecting.
new knoweledge supplied by computor programs


Hi Art,

More baloney cut thick. You have NOWHERE offered any discussion of
ANY new knoweledge (sic); but you hug such manufactured sentiments
like an emotional life preserver.

You rctleeny challngeed Roy for his athortuy. You wloud do well to
leran spllenig bfoere ripeteang that aigan.

What I want to know is how we are going to alter reality when the
computer program shows it is wrong!




- Mike KB3EIA -

"Roy Lewallen" wrote in message
...
wrote:
. . .
Now Roy I have a problem with what you are saying here
I spend hours modelling an array to lower the TOA or angle of max
radiation
which directly controls the main lobe dimension both in width and height.

And, as I've said quite a few times in one way or another, it's largely a
waste of time.

O.K. Roy let's get down to the nitty gritty and look at this question.
Your background in antenna programs makes you a person of choice
to declare if what I do is a waste of time and where I must default to an
experts judgement.
A month or so ago I gave a description of the antenna that I modelled
and for your interest I used the AOP program by Beasely a person
that you have collaborated with in the past.
One can design a yagi antenna with 8 elements say on a 60 foot boom
and then note the gain and the elevation angle of maximum gain.
This can be done using the most basic antenna program available.

The next step is to apply this same antenna to a program that is capable
of changing dimensions to obtain a desired function ,which in this case can
be
"Gain". There is reference to a NEC program on this group during the past
week
or so that I believe is capable of doing this, that is on the web and also
free to all.
With the use of variable dimensions which includes best x,y and Z positions
for various pulses or physical positions the program will procede to do as
asked.

This test is about as simple as it gets to show how the angle of max
radiation can be changed
as well as the envelope of the new angle range to achieve a 3 dB window of
radiation

You will see that the computor program will immediately remove itself
from a Yagi design to obtain a better gain and form an array that consists
of one driven element and where the rest are all reflectors!
Though the final shape appears to represent a dish it is not, it is simply a
design with multiple dimentional reflectors in the best coupling mode.
The result is a gain figure that will exceed the original design,
which is what we requested of the program i.e.allow it to make changes of
choice
to achieve a higher gain than the initial yagi design
With the above. one can change the elevation angle for maximum gain which
has now
dropped to a 11 to 10 degrees or even 9 degrees if one is willing to
sacrifice some gain.
This can be also be achieved by allowing the driven element to deviate from
a straight dipole
to a vee shape tipped in such away to helps control reactance swings of the
total array.
The above is quite simple to duplicate, where anybody can place a 8 element
yagi with a long boom
of 60 ft placed over real ground and challenge the program to devise a way
of increasing gain.
In my case the program changes to a non director mode without any prodding,
other programs
may well need some prodding. Changes to elevation for maximum gain will
change automatically
and one can expect to easily devise an array with a 10 degree angle where a
gain of 16 dbi is attained
as well as a broader lobe than can not be accomplished with a Yagi design.
If you find that you cannot repeat the above results in a short space of
time then it surely reflects
a misuse of programs on my part.
Please note that propagation has no part in forming the shape of the main
lobe to the
best of my understanding but you would know better than most as to what the
program parameters actually are
I look forward to your response or any other program users response that
shows my findings
are a waste of time so I can direct my experimentation in a more fruitfull
direction.
Best regards
Art




I model an antenna array such that it emulates in a way a "stacked"
array where as low as a 9/10 degree TOA. The 3 db gain window is broader
in width and narrower
in height than say the normal array. It is this "TOA" that determines
what window we have and
where it hits the ionesphere which thus determines its point of arrival
on the earths surface
snip


Is this the error of my ways where any change I make to an antennas
pattern
is rendered of no use because I must first find a way to manipulate
propagation
where all the action is really at?
. . .

Close. Sometimes two or more propagation modes are possible, such as
snip
any case, it doesn't matter how much I'm radiating at 1, 5, 7, or 15
degrees, or what my antenna's maximum angle is. All that counts is how
much I'm radiating at 3 or 12 degrees.
Snip


I also want to make it clear that I appreciate your post which I see as
an attempt to clarify matters
that are presently being discussed ie.It is propagation and not the
antenna that determines the
TOA. Or "antenna pattern is determined by propagation" so that we
don't get hung up
on the term TOA

snip

I suggest downloading the excellent, free, and easy to use propagation
software by Shel Shallon, W6EL, http://www.qsl.net/w6elprop/. In a few
minutes, you'll be able to see what angles are supported at a given time
and frequency for a given path.


Best regards
Art
Roy Lewallen, W7EL