Dave wrote:
All other "definitions" are red herrings and do not contribute to the
answer.

Not if the question is: What is beam efficiency? :-)
--
73, Cecil http://www.w5dxp.com

My thoughts exactly information is not really sort only an excuse to
snipe
Movement in any science is by increments of knoweledge though I do
believe absolute miricles do occur Seems like people only want
questions that they have answers for not items that create original
thought. Seems also that many believe that radiating methods have been
exhausted but every year the patent ofrfice issue different designs. I
have found during my life when I have been given a patent that people
will say thats obvious or I knew that or that should be shared with me
evry one being after the fact. Such people are not interested in
anything new unles they read about it in a book or they will state that
they do not understand. I started out with the intent of explaining a
new technology with respect to radiation but I cannot continue as we
have sniping starting with the question. A few months ago I started
with a question and nobody liked it so after some time I decided to
word the question as they said it should have been stated......Well
they have now donned different hats and are aiming for the original
question again.. You just can't win if you are in a information sharing
mode with people who are confinced they know it all and that is why
they are sniping. Now since my education value is considered in doubt I
will back off so that those who perceive themselves as experts will
carry on the load for others who may be interested in knoweledge but
only if they know everything such that they can critisize.
Has anybody pointed to a flaw in the Yagi design and the cause of it
and what idealy could be done to improve things? Ofcourse not, their
forte is to throw stones pure and simple.
I can understand it from Roy since he has a personal financial interest
in conversations revolving around Yagi antennas. But some of the others
have been known to produce absolutely nothing to the subject. Even
Cecil who I suggest with his extra deep physics
education gets mocked sometimes from people with I suspect just a high
school graduation that is the school stood on a hill. Check out the
responses so far to get an understanding
of the people that you are dealing with starting with Turner who with
his vast background of educatiate has taken on the task of judging mine
as demeaning as one of the lowest of the low. What has he achieved in
life or with antenna design to allow him to assume the mantle of
nobility which he does not share so that others may learn? Are there no
positive thoughts out there about antennas or to phrase an answer to
what they believe is the question. ?
At the moment I have only heard about negatives that prevent posting
from showing their expertise that they believe they have and where at
the present time we can only trust.
Has anybody supplied a efficiency number of anything to do with this
question or what they perceived was the querstion explaining in detail
how they arrived at a particular position rather than just guessing,any
one, anybody nothing positive anything positive?
jawod wrote:
art wrote:
Hi Jerry perhaps I am wrong that there ARE people who want to talk
antennas
We went thru this some time ago and I was referring to efficiency of
the yagi antenna
with respect to the radiation field where much is reflected to areas of
no concern.
Others did not like this and said efficiency referred to is one of the
radiation facets of a radiating array and the yagi is efficient and
then the sniping statrted and the newsgroup went down hill as others
joined to emulate and perpetuate abrasive non antenna related
subjects. I just popped back to see if the group wanted to change back
to antenna talk
and posted the term efficiency of the yagi in terms of radiation which
everybody was
auguing about. Well things haven't changed they still just want to
throw stones and more will join in as the thread goes on., Ill stick it
out for an hour or so and then move on again.
Cant wait for somebody to compare with free space stuff to add to the
confusion, I know it will come




Jerry Martes wrote:

"art" wrote in message
roups.com...

Some time ago I mentioned how inefficient Yagi design
antennas were thinking more in the way of how little of
the radiation used got to its required direction.
At that time people said the antenna was efficient though
they wanted to talk about
actual radiation efficiency and the sniping began
.Nobody but nobody came back with the radiation
efficiency of a Yagi as they saw the question, they
just wanted to throw stones.Imagine that antennas
was not what the experts wanted to talk about and
the newsgroup took a turn for the worst
So I join in with the thoughts of radiation efficiency
of a yagi unless you prefere to give up this antenna
newsgroup. But before you scream out and throw
stones again I will referr to efficiency as most of the
members of this group what's left of them think of the term.
So let's look at that if that is what you preferr..

The basic small yagi has three elements one driven,
one a reflector and one a director yet only one
element has a truly resistive impedance whereas
the other two do not. Since two elements out of the
three are producing reactive impedances and wherein
the reactive portions of impedance is pure waste
pray tell me how one can consider a yagi as efficient?
And please, please don't waste time on "I don't understand"
otherwise everything drops down to the subject of spark noise
which was really decided by hams a long while ago.
On the other side of the coin, if the reactive portion of an
impedance is not waste then why is LCR
type mesh circuitry only revolve around lumped circuitry?
HINT add up the power emminating from each element
P =I sq times real resistance for those who are just followers.

There again maybe it is best that you be honest and say
you don't understand! Better that than join those who have
nothing to say about antennas!


Hi Art

OK, I dont understand. Perhaps I could begin to understand if I was
given the definition of efficiency we are using in this discussion. How do
you define efficiency?

Jerry


It troubles me that so many wish to "hold court" on this NG. Establish
obscure, bizarre or downright wrong rules of discovery to pump up their
own egos. So much opportunity to share advice in a collegial fashion,
realizing the breadth (or shallowness) of understanding that exists
amongst "us".

Is Elmer really dead?

John
AB8O

Cecil Moore wrote:

Actually Art, adding reactance reduces the current in
the element thus *decreasing* losses below what a resonant
passive element would have. Pure reactance is lossless.

Cecil:

On the surface, this is all very correct, however, you cannot induce
reactance without inducing some value (albeit it may, or may not, be
trivial) of pure resistance (ohmic dc), barring the use of
superconducting material, of course.

I think Art does see that that either magnetically or capacitively (and
both most likely) the resistance and all other aspects of the director
and reflector are being introduced into the driven element's circuit.
This I see stated in his original post and ...

However, how big is that fly speck(s) under your microscope is yet
another question and those answers ...

Warmest regards,
JS

Dave wrote:
If a simple dipole is fed with 100 watts and radiates 95 watts, it is 95% efficient.

David if you had a dipole that had inherrent directional capabilities
would you consider
that as a possible choice for better efficiency ? Where does the 95%
number come from and where did the 5% go so. Did turners post influence
your guess at that number? is he worth copying? Others can get an idea
what you are talking about ie. parameters of use for which you are
applying the 95% figure to. It is possible that we can at least one
negative from the discusion in search of the kernel of info. Does the
dipole become more or less efficient as it moves away from its design
frequency as it becomes "detuned" Give me some meat





snip/s/ DD

art wrote:

Some time ago I mentioned how inefficient Yagi design
antennas were thinking more in the way of how little of
the radiation used got to its required direction.
At that time people said the antenna was efficient though
they wanted to talk about
actual radiation efficiency and the sniping began
.Nobody but nobody came back with the radiation
efficiency of a Yagi as they saw the question, they
just wanted to throw stones.Imagine that antennas
was not what the experts wanted to talk about and
the newsgroup took a turn for the worst
So I join in with the thoughts of radiation efficiency
of a yagi unless you prefere to give up this antenna
newsgroup. But before you scream out and throw
stones again I will referr to efficiency as most of the
members of this group what's left of them think of the term.
So let's look at that if that is what you preferr..

The basic small yagi has three elements one driven,
one a reflector and one a director yet only one
element has a truly resistive impedance whereas
the other two do not. Since two elements out of the
three are producing reactive impedances and wherein
the reactive portions of impedance is pure waste
pray tell me how one can consider a yagi as efficient?
And please, please don't waste time on "I don't understand"
otherwise everything drops down to the subject of spark noise
which was really decided by hams a long while ago.
On the other side of the coin, if the reactive portion of an
impedance is not waste then why is LCR
type mesh circuitry only revolve around lumped circuitry?
HINT add up the power emminating from each element
P =I sq times real resistance for those who are just followers.

There again maybe it is best that you be honest and say
you don't understand! Better that than join those who have
nothing to say about antennas!

Dave wrote:
If a simple dipole is fed with 100 watts and radiates 95 watts, it is 95% efficient.

David if you had a dipole that had inherrent directional capabilities
would you consider
that as a possible choice for better efficiency ? Where does the 95%
number come from and where did the 5% go so. Did turners post influence
your guess at that number? is he worth copying? Others can get an idea
what you are talking about ie. parameters of use for which you are
applying the 95% figure to. It is possible that we can at least one
negative from the discusion in search of the kernel of info. Does the
dipole become more or less efficient as it moves away from its design
frequency as it becomes "detuned" Give me some meat





snip/s/ DD

art wrote:

Some time ago I mentioned how inefficient Yagi design
antennas were thinking more in the way of how little of
the radiation used got to its required direction.
At that time people said the antenna was efficient though
they wanted to talk about
actual radiation efficiency and the sniping began
.Nobody but nobody came back with the radiation
efficiency of a Yagi as they saw the question, they
just wanted to throw stones.Imagine that antennas
was not what the experts wanted to talk about and
the newsgroup took a turn for the worst
So I join in with the thoughts of radiation efficiency
of a yagi unless you prefere to give up this antenna
newsgroup. But before you scream out and throw
stones again I will referr to efficiency as most of the
members of this group what's left of them think of the term.
So let's look at that if that is what you preferr..

The basic small yagi has three elements one driven,
one a reflector and one a director yet only one
element has a truly resistive impedance whereas
the other two do not. Since two elements out of the
three are producing reactive impedances and wherein
the reactive portions of impedance is pure waste
pray tell me how one can consider a yagi as efficient?
And please, please don't waste time on "I don't understand"
otherwise everything drops down to the subject of spark noise
which was really decided by hams a long while ago.
On the other side of the coin, if the reactive portion of an
impedance is not waste then why is LCR
type mesh circuitry only revolve around lumped circuitry?
HINT add up the power emminating from each element
P =I sq times real resistance for those who are just followers.

There again maybe it is best that you be honest and say
you don't understand! Better that than join those who have
nothing to say about antennas!

No Jerry you are on the right path, the envelope under question is the
application of power that produces the emmission of flux in the near
field You have to be carefull as to what radiation refers to and where
or sniping will start because some radiation starts in the near field
does not really take off because of radiation that cancells or
neutralises the emitted flux
so far field radiation does not occur so you have to be carefull after
the flux flows when you really only have two fields acting in concert
You will also here people refer to the gain of a radiated field as an
indication of efficiency which is just comparing the position of choice
to another position iof choice without regard to the volume enclosed in
a radiation field which is normally spread in all directions whether
you want it or not. So we are looking strictlyat how much energy we
lose in the providing flux emmisions which profides radiation without
concern where it goes otherwise you will get into a sqogmire of
confusion. Frankly I can tell you that a element detuned is the root of
all the inefficiences experienced with a Yagi.Period
but others resist this notion or fact
Art




Jerry Martes wrote:
"art" wrote in message
ps.com...
Hi Jerry sorry that I didn't respond to you earlier but here goes
untuned elements which haveWhen you decide to get something going you
need a means to get there.
When you decide on the means you need to know if you are expending the
minimum energy to get there
In this particular case we have decided on generating a time varying
field around some reradiatiung elements to obtain a radiating field of
some sort Since we are applying energy
to elements we want to know if the elements are doing a good job or are
they losing out on energy translation by generating heat e.t.c instead
of it all going where I want it to. So what we do is find out what
energy we put in to obtain our objective and measure what we got out
towards our objective to see how effective we were which is a measure
of efficiency... Ideally we dont want to produce heat and all that
other stuff but the anteena array that we have chosen to do this is a
yagi array of elements which starts of with a resonant dipole which has
a purely resistive impedance. But the yagi then goes on to upset things
by adding which have a reactive impedance which detracts from the purly
resistive value of the impedance which means losses when we should have
added extra resonant elements to the set up as a means of adding to the
structure to maintain zero losses BUT the yagi does go a long way
towards our objectives so it has hung around for a long while. As a
side issue
we should also consider the environment that our array is working in
and also the type of element material we are using as well as the means
taken to input power but that gets more complicated so the question is
really revolving around the energy input versus a magnetic near field
generation that goes on to form a far field radiation field.
SOOOOOOOooooo
efficiency in this case compares the electrical power applied to the
yagi to generate a magnetic and electric fieldaround the yagi and to
check how much energy was lost on the way to our objective. Sorry for
the delay but fortunately I did check back in before I moved on to
other things
Regards
Art

Hi Art

As I read it, the efficiency (in percentage) we are using for this
discussion is Power Out divided by Power In, if the "objective" is to
radiate power. Or, correct me if I misread.

Jerry

art wrote:
...

Art:

You believe resonance of the driver is desirable? Have you plotted a
yagi with EZNEC and added reactance to make the director physically
shorter than the de, but the electrical length correct?

I have not; but would expect it to plot out as two identical de's
pattern with a reflector?

JS

Cecil Moore wrote:

Dave wrote:

All other "definitions" are red herrings and do not contribute to the
answer.


Not if the question is: What is beam efficiency? :-)

ABSOLUTELY NOT!!!!

Efficiency is the ratio of [power input minus power losses] divided by [power
input]. PERIOD!!!!!!!!!

If it's anything else you have created a perpetual motion machine ... patent it!!!

This thread has been corrupted by confusion with directivity and gain. Neither
of which have anything to do with efficiency. Antenna patterns provide zero
information regarding efficiency.

It is possible, for this discussion, to have a Yagi with 10 dB gain, -60 dB
backlobes, and 10 dB losses and it is only a 10% efficient antenna that exhibits
a gain of 0 dBd. It is still 10% efficient.

Art, who made the original post, has to resolve his difficulties with antenna
efficiency, antenna system efficiency, path loss effects, gain and directivity.

Cecil, as an engineer, you should not slide into loose definitions of
efficiency. Doing so only further confuses the issue.

Art is using 'efficiency' incorrectly. His actual interest is in the total path
loss from transmitter to receiver and should be dealt with in that context. And
in that problem, path loss, the issues are further complicated between line of
sight, ground wave and over the horizon propagation effects. HF path losses can
have -60 dB variations, or more loss, depending on propagation, solar cycles,
and solar storms. We have all experienced QSB of up to 5 S units and also total
loss of signals due to solar effects. These effects are NOT YAGI ANTENNA EFFICIENCY.

"art" wrote in message
ups.com...
No Jerry you are on the right path, the envelope under question is the
application of power that produces the emmission of flux in the near
field You have to be carefull as to what radiation refers to and where
or sniping will start because some radiation starts in the near field
does not really take off because of radiation that cancells or
neutralises the emitted flux
so far field radiation does not occur so you have to be carefull after
the flux flows when you really only have two fields acting in concert
You will also here people refer to the gain of a radiated field as an
indication of efficiency which is just comparing the position of choice
to another position iof choice without regard to the volume enclosed in
a radiation field which is normally spread in all directions whether
you want it or not. So we are looking strictlyat how much energy we
lose in the providing flux emmisions which profides radiation without
concern where it goes otherwise you will get into a sqogmire of
confusion. Frankly I can tell you that a element detuned is the root of
all the inefficiences experienced with a Yagi.Period
but others resist this notion or fact
Art


Hi Art

Does that mean the Yagi gets hot when used to radiate RF? That is,
since the Yagi is less efficient than some other reference antenna, the Yagi
gets hotter than the other antenna when their input power is equal.

Jerry

I understand where you are coming from Cecil but let me turn your
statement around. How are you going to account for these additions and
subtractions in accepted equations by the masters that produce the
legitamacy of RLC or complex circuitry equeationd if they are known as
loss less and not a lumped item around which electromechanics thrive?
Cecil Moore wrote:
art wrote:
But the yagi then goes on to upset things
by adding which have a reactive impedance which detracts from the purly
resistive value of the impedance which means losses ...True it does have directive value
as cos phi or power factor but it is a variable and not a constant
which circuitry requires.
Remember only R is of consideration for the addition of power from each
element which provides flux unless you can quantasize reaction for me
as producing the emmision of flux other than a indication of the
direction it takes . Really Cecil I am trying to get people to think
about elements containing inherranr directional properties so that
uneeded radiation is harnessesd for useful purposes but they are
shutting their ears.
Art

Actually Art, adding reactance reduces the current in
the element thus *decreasing* losses below what a resonant
passive element would have. Pure reactance is lossless.

Seems to me that the reactance in the passive elements
provides a phase shift that causes destructive interference
in the desired places and constructive interference in
the desired places.

I came in late and thus apologize if anyone else has stated
this earlier.
--
73, Cecil http://www.w5dxp.com