Yagi efficiency
 

Very good points John, the subject first started out some time ago when
I stated that thge yagi array was really an in efficient way of
providing communication point to poit because it can be seen that the
radiation field points all over the place. The comments first came back
that little energy was exposed outside the main lobe which then people
stated it wasn't a measure of yagiefficiency bringing gain and a lot of
miscellaneous stuff until they got to the point that the yagi was
efficient and the real efficiency revolves around radiation itself.
Then sniping started and I took off for a while.
When I came back I modified the question
to what people thought the question should be because that was what
they had an answer for but again they got screwed up because the
subject still remaines the yagi with respect to radiation fields
knowing full well that radiation cancellation enters heavily when
determining final radiation fields which is why one should not bring in
gain to the picture. So cutting out the clutter of environment and
dielectrics used etc the question is phrased around the transfer
arrangement that the Yagi uses to translate a electrical power input
for the production of a time varying field which is the most simple
basic aproach since we are dealing only with the eIR equation in
obtaining the energy change over efficiency with respect to the Yagi
antenna alone.No nead to show off your perceived knowelenge about
antennas or to change the subject so that one doesn't have to show
their ignorance of factors outside of Ohms law which is all one needs
to know. But sadly in this newsgroup people get upset if one doesn't
know the answer to the question prefer to divert things to a question
that they do know the answer to and do this by questioning the
intelligence of the poster first before their own intelligence becomes
the question. From the very beginning I gave the hint where it can be
reasoned out without a lot of uninportant clutter but unfortunately all
ignored it as possible drivel. Is it any wonder that antenna talk and
aspiring amateurs shy away from this newsgroup and where it attracts a
different sort of clientele in line with present day activities? My
goodness a dipole is a basic element in any antenna array with respect
to effiency but an arrays efficiency is based on the additions to the
driven dipole of other elements used to produce the near field to
produce perceived benefits which is outside of this question. I realise
that all hams do not have to be electrical engineers but it does seem
the purpose of some is to complicate things beyond the comprehension of
those who we wish to have in the fraternity in an attempt to elevate
them selves in fraternity fashion. Oh well I can't change the world!
The yagi has held its own since the 1920 so it must be sacrelidge to
examine it furthur to expose more efficient means of producing near
fields. For myself I have written around a new form to be published by
the PTO and was intending to discuss its merits with this group first
but I now realise that information iand knoweledge is not what is sort
after, only targets to throw stones at.



John Smith wrote:
Jerry Martes wrote:
...
How do you define efficiency?

Jerry



Jerry:

You make that sound like such a simple question.

Antenna efficiency is a complicated and often misused figure.

All antennas suffer from losses. A simple horn antenna for example will
not be as efficient as a perfect aperture of the same size because of
phase offset. The real efficiency of an antenna combines impedance match
with other factors such as aperture and radiation efficiency to give the
overall radiated signal for a given input. The best and mostwidely used
expression of this efficiency is to combine overall efficiency with
directivity (of the antenna) and express the efficiency times
directivity as gain.


The above is NOT mine, but taken from the web...
http://www.tmcdesign.com/antenna%20c...nformation.htm

So, we need to know if we are discussing antenna efficiency, or
radiation efficiency, or the skin effect as related to the ether
efficiency, etc. grin

Good that you are asking him!

Regards,
JS

Yagi efficiency
 

art wrote:

providing communication point to poit because it can be seen that the
radiation field points all over the place. The comments first came back

Art:

Antennas are simply, I mean let's face it, they are just a bunch of
metal and insulators!

However, they are very complex, this can be demonstrated with math or
Roy's excellent little visual aid, EZNEC.

I don't think you are a "smart ass" or "diabolically argumentative", you
are simply lost in this--as we ALL are.

It is a learning curve, some here help speed us along this curve, some
offer "other things." I know what you mean.

All antennas end up being a compromise of size, building ease,
materials, weight, wind resistance (wind loading), what neighbors will
tolerate in "artistic design", directional patterns, cost, etc., etc.

Really, there is no such thing as "the most efficient" antenna--least
not when you have to design an antenna for the real world. I think most
answers to your question(s) will seem vague to you, this is not because
of deliberate intent on those answering, it just goes to point out the
complexity of your most "simple questions" and the different
interpretations which can spring forth from even the most simple question.

Patience is a skill which benefits one in all pursuits one engages in...

Warmest regards,
JS

Yagi efficiency
 

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

If a simple Yagi is fed with 100 watts and radiates 95 watts, it is 95% efficient.

If a full size 11 element Yagi is fed with 100 watts and radiates 95 watts, it
is 95% efficient.

What is your real question regarding efficiency?

/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!

Yagi efficiency
 

Cecil Moore wrote:

Bill Turner wrote:


On 2 Dec 2006 05:36:05 -0800, "Denny" wrote:

... From that number you can very
simply calculate what percentage went into the lobes you prefer and
what went in the lobes you don't prefer...


The problem here is not math, it's English. You are calculating gain
and/or directivity, not efficiency.


Maybe beam efficiency? (cone beam power)/(total radiated power)

C'mon Cecil, you know exactly what efficiency is!

[Pin - Ploss}/Pin

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

Yagi efficiency
 

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

How are you measuring the antennas "output" or "radiated power?"
--and--
How much of that 95 watts is spent in heating the dielectrics and metal
(or is that "missing" 5 watts the heating power? And, how did you
measure that?)

JS

Yagi efficiency
 

RADIATED VERSUS LOSSES

John Smith wrote:

Dave wrote:

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


How are you measuring the antennas "output" or "radiated power?"
--and--
How much of that 95 watts is spent in heating the dielectrics and metal
(or is that "missing" 5 watts the heating power? And, how did you
measure that?)

JS

Yagi efficiency
 

Dave wrote:
RADIATED VERSUS LOSSES

Hmmm. I am looking around for my "RADIATED VERSUS LOSSES" meter, can't
seem to find it, must have lost it. Too bad, have to run down to radio
shack and pick up another to double check you! Will get back to you then...

JS

Yagi efficiency
 

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!

My cat has mittens.
MK

Yagi efficiency
 

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

Yagi efficiency
 

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 ...

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

Yagi efficiency
 

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

Yagi efficiency
 

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

Yagi efficiency
 

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

Yagi efficiency
 

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!

Yagi efficiency
 

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!

Yagi efficiency
 

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

Yagi efficiency
 

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

Yagi efficiency
 

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.

Yagi 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

Yagi efficiency
 

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

Yagi efficiency
 

John Smith wrote:
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


.... sorry "... resonance of the driver ...", should have been resonance
of the director.

JS

Yagi efficiency
 

Jerry Martes wrote:
"art" wrote in message

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



Yes Jerry, if the radiation efficiency falls, the antenna should get
"hotter", where else would the lost power go? Harmonics? Psychic waves?

JS

Yagi efficiency
 

Help me help me please , a detuned element has a reactive impedance
value, simple fact.
Now with your superior knowledge and education show not just me but all
of us how the production of a reactive impedance does not or cannot
impede the formation of emmited flux? I dont want just comments or
guesses just an explanation of your position which aligns with the laws
of Kirchoff, Ampere, Green ,Laplace etc as a group or as single people
to give your response some credability . Cecil has given you a starting
point as to what exactly reactance is so the rest should be easy for
you considering how easily you can dismiss my logic and education
regarding the Yagi antenna. Bill I cant wait to hear the mutterings of
a master of your station, a chance to learn something really new, maybe
not even written in a book Go man go! Well I know you can't.... but I
am just demonstrating that if you want to snipe then others will be
encouraged to snipe and it is not nice. Knoweledge is what I am after
not errent gun shots



Bill Turner wrote:
ORIGINAL MESSAGE:

On 1 Dec 2006 18:29:51 -0800, "art" wrote:


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?

------------ REPLY FOLLOWS ------------

Please let us know what electronics school you attended so we can
avoid it like the plague and, if at all possible, have it
de-certified.

Thanks,

Bill, W6WRT

Yagi efficiency
 

From a theoretical way of getting at the answer it seems
a logical way of proceding. So now to the rest of the task.1 how do we
determine volumes that you talk about that are a result of deflection 2
How do we determine
radiation that was cancelled or neutralised and 3 How do you determine
the radiation volume created by ground reflection so we can work back
to search for ground losses. That last one really bothers me as I have
never got a good handle on the contribution of ground reflection to any
particular part of the radiation envelope.

Art



Denny wrote:
For those who wish to actually learn and not just insult each other,
get a calculator, learn how to calculate Cosine Theta a trivial math
problem that any 9th grader can be taught in 5 minutes flat, get a BIG
piece of paper reason to come, and actually calculate the shape and
vector length of the lobes of a two element Yagi-Uda antenna... Do the
calculation in both the horizonal and vertical planes... From that you
can calculate the volume of each lobe, which is proportional to the
percentage of power in each lobe... From that number you can very
simply calculate what percentage went into the lobes you prefer and
what went in the lobes you don't prefer...

Now, the reason for the BIG piece of paper... The antenna patterns you
see on the screen with EZNEC, or in the antenna handbooks, are
logarithmic, not linear and there are flavors to them, ARRL, linear
logarithmic, modified logarithmic... So, the patterns are
distorted... Why is that? Because if they were linear and the front
lobe and the rear lobe are to the same scale the front lobe will take
up the entire length of the screen/paper and the rear lobe will need a
magnifying glass to be seen... A rear lobe that is 20dB down from the
front lobe is down by the power ratio of 100... So, if your forward
lobe calculates out to be 10 inches long, the rear lobe will be be 1/10
of an inch.... I'll let you figure out the size of a lobe that is 30dB
down (get out your microscope)

For those who want to review do a search on Joseph Reisert, who has
published numerous writings on antennas and patterns... There many are
others also, but Joe is published on the web, and very readable...

cheers ... denny / k8do

Yagi efficiency
 

art wrote:

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

SNIPPED

Art, It has absolutely NOTHING to do with measurements, or with 95 watts or 5
watts, or antenna patterns, or the reactive components.

It is defining efficiency properly!

Net radiated power divided by power input is Efficiency. Measure it or calculate
it any way you want!

An antenna with -3 dB loss is a 50% efficient antenna independent of the actual
input power. Choose any power input you like. An antenna with -3 dB loss is a
50% efficient antenna regardless of gain, directivity, antenna patterns,
patents, claims, marketing Bull S--t, or anything else.

Put your favorite antenna inside a sphere of any suitable diameter that contains
the antenna. The total rf power coming out of the sphere divided by the total rf
power into the antenna [sphere] is the antenna efficiency. There is NO OTHER
definition!

Reducing power in the back and side lobes has absolutely NOTHING to do with
efficiency. It has to do with directivity.

Design of a Yagi, traps, conductors, element spacing etc. will produce
variations in gain, directivity, efficiency [variations in losses, heat].
Practically, the difference in efficiency between a 90% efficient antenna and a
98% efficient antenna is swamped by variations in the path loss physics.

I spent years of my life designing rf systems for telemetry from space vehicles
through reentry to a ground station. Data integrity at the ground station was
and still is the dominating requirement. Based on allowable data error rates,
the total path equation required S/N ratios of 12 dB or more. The solution is a
systems solution where the minor variations in antenna efficiency get lost in
the calculations.

Yagi efficiency
 

art wrote:

Help me help me please , a detuned element has a reactive impedance
value, simple fact.

NOT CORRECT! It is a complex impedance that contains both a resistive and an
reactive component.

Now with your superior knowledge and education show not just me but all
of us how the production of a reactive impedance does not or cannot
impede the formation of emmited flux? I dont want just comments or
guesses just an explanation of your position which aligns with the laws
of Kirchoff, Ampere, Green ,Laplace etc as a group or as single people
to give your response some credability . Cecil has given you a starting
point as to what exactly reactance is so the rest should be easy for
you considering how easily you can dismiss my logic and education
regarding the Yagi antenna. Bill I cant wait to hear the mutterings of
a master of your station, a chance to learn something really new, maybe
not even written in a book Go man go! Well I know you can't.... but I
am just demonstrating that if you want to snipe then others will be
encouraged to snipe and it is not nice. Knoweledge is what I am after
not errent gun shots



Bill Turner wrote:

ORIGINAL MESSAGE:

On 1 Dec 2006 18:29:51 -0800, "art" wrote:



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?

------------ REPLY FOLLOWS ------------

Please let us know what electronics school you attended so we can
avoid it like the plague and, if at all possible, have it
de-certified.

Thanks,

Bill, W6WRT

Yagi efficiency
 

Dave wrote:

SNIPPED

Art, It has absolutely NOTHING to do with measurements, or with 95 watts
or 5 watts, or antenna patterns, or the reactive components.

It is defining efficiency properly!

Net radiated power divided by power input is Efficiency. Measure it or
calculate it any way you want!

An antenna with -3 dB loss is a 50% efficient antenna independent of the
actual input power. Choose any power input you like. An antenna with -3
dB loss is a 50% efficient antenna regardless of gain, directivity,
antenna patterns, patents, claims, marketing Bull S--t, or anything else.

Put your favorite antenna inside a sphere of any suitable diameter that
contains the antenna. The total rf power coming out of the sphere
divided by the total rf power into the antenna [sphere] is the antenna
efficiency. There is NO OTHER definition!

Reducing power in the back and side lobes has absolutely NOTHING to do
with efficiency. It has to do with directivity.

Design of a Yagi, traps, conductors, element spacing etc. will produce
variations in gain, directivity, efficiency [variations in losses,
heat]. Practically, the difference in efficiency between a 90% efficient
antenna and a 98% efficient antenna is swamped by variations in the path
loss physics.

I spent years of my life designing rf systems for telemetry from space
vehicles through reentry to a ground station. Data integrity at the
ground station was and still is the dominating requirement. Based on
allowable data error rates, the total path equation required S/N ratios
of 12 dB or more. The solution is a systems solution where the minor
variations in antenna efficiency get lost in the calculations.


Art doesn't care about reality, he thinks he can create a new one which
ignores physics. You are wasting your time.

I am plonking this thread, and art.

tom
K0TAR

Yagi efficiency
 

John Smith wrote:
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?
Yes I have done that lots of times if I have the question correctly
basically having resonant elements beside the driven element but of
different lengths

I have not; but would expect it to plot out as two identical de's
pattern with a reflector?
Well now I am not sure what you want plotting if you are making the
reflector resonant
other than the design frequency of the array.

JS

Yagi efficiency
 

art wrote:
Well now I am not sure what you want plotting if you are making the
reflector resonant
other than the design frequency of the array.
JS


Art:

No, the reflector would remain the same ~5% longer (electrically and
physically) than the de. And, the director remains physically shorter
than the de, but made resonate with the proper addition of a coil,
somewhere in its length, so as to be made resonate at the same freqs as
the de (or approx. so, since the coil will undoubtedly change some
characteristics from that of the resonate de.

Art, you are rapid losing me here. Either I am not able to see what you
are getting at, or else I suspect you of having some facts or formulas
twisted about here...

Regards,
JS

Yagi efficiency
 

David, you are doing a lot of reading of different posters and then
placing them under my name. I have no idea of what you are trying to
project with this accumulation of various postings from various people
tho I cqan see that you are getting mad as hell over something.
cool down

Dave wrote:
art wrote:

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

SNIPPED

Art, It has absolutely NOTHING to do with measurements, or with 95 watts or 5
watts, or antenna patterns, or the reactive components.

It is defining efficiency properly!

Net radiated power divided by power input is Efficiency. Measure it or calculate
it any way you want!

An antenna with -3 dB loss is a 50% efficient antenna independent of the actual
input power. Choose any power input you like. An antenna with -3 dB loss is a
50% efficient antenna regardless of gain, directivity, antenna patterns,
patents, claims, marketing Bull S--t, or anything else.

Put your favorite antenna inside a sphere of any suitable diameter that contains
the antenna. The total rf power coming out of the sphere divided by the total rf
power into the antenna [sphere] is the antenna efficiency. There is NO OTHER
definition!

Reducing power in the back and side lobes has absolutely NOTHING to do with
efficiency. It has to do with directivity.

Design of a Yagi, traps, conductors, element spacing etc. will produce
variations in gain, directivity, efficiency [variations in losses, heat].
Practically, the difference in efficiency between a 90% efficient antenna and a
98% efficient antenna is swamped by variations in the path loss physics.

I spent years of my life designing rf systems for telemetry from space vehicles
through reentry to a ground station. Data integrity at the ground station was
and still is the dominating requirement. Based on allowable data error rates,
the total path equation required S/N ratios of 12 dB or more. The solution is a
systems solution where the minor variations in antenna efficiency get lost in
the calculations.

Yagi efficiency
 

David are you going nuts? I used the word impedance whichcan mean two
components only one of which is used for power. What on earth are you
trying to say now or are you looking for a reason to thro stones. Now
calm down and point out where I was not CORRECT as you put it and what
are the consequences of this error relative to what we are talking
about?
If your point is that I didn't emphasise the word complex then there is
no need to respond, you can have it your way I don't mind if it helps
you out with your apparent anger.


Dave wrote:
art wrote:

Help me help me please , a detuned element has a reactive impedance
value, simple fact.

NOT CORRECT! It is a complex impedance that contains both a resistive and an
reactive component.

Now with your superior knowledge and education show not just me but all
of us how the production of a reactive impedance does not or cannot
impede the formation of emmited flux? I dont want just comments or
guesses just an explanation of your position which aligns with the laws
of Kirchoff, Ampere, Green ,Laplace etc as a group or as single people
to give your response some credability . Cecil has given you a starting
point as to what exactly reactance is so the rest should be easy for
you considering how easily you can dismiss my logic and education
regarding the Yagi antenna. Bill I cant wait to hear the mutterings of
a master of your station, a chance to learn something really new, maybe
not even written in a book Go man go! Well I know you can't.... but I
am just demonstrating that if you want to snipe then others will be
encouraged to snipe and it is not nice. Knoweledge is what I am after
not errent gun shots



Bill Turner wrote:

ORIGINAL MESSAGE:

On 1 Dec 2006 18:29:51 -0800, "art" wrote:



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?

------------ REPLY FOLLOWS ------------

Please let us know what electronics school you attended so we can
avoid it like the plague and, if at all possible, have it
de-certified.

Thanks,

Bill, W6WRT

Yagi efficiency
 

Tom Ring wrote:
Dave wrote:
...
I am plonking this thread, and art.

tom
K0TAR

Ahhhh. Mr. Tom Ring. I would almost bet he shares much in common with
the average IBM employee!

Graduated with a C+ grade point average!

JS

Yagi efficiency
 

Tom it is no good plonking me for what david is saying because he is
not quoting me, in fact some of it is a requote of what he said not me.
I think he is creating a straw man that he can argue with, is that what
you call reality? He has spent most of his time in space and I believe
him

Tom Ring wrote:
Dave wrote:

SNIPPED

Art, It has absolutely NOTHING to do with measurements, or with 95 watts
or 5 watts, or antenna patterns, or the reactive components.

It is defining efficiency properly!

Net radiated power divided by power input is Efficiency. Measure it or
calculate it any way you want!

An antenna with -3 dB loss is a 50% efficient antenna independent of the
actual input power. Choose any power input you like. An antenna with -3
dB loss is a 50% efficient antenna regardless of gain, directivity,
antenna patterns, patents, claims, marketing Bull S--t, or anything else.

Put your favorite antenna inside a sphere of any suitable diameter that
contains the antenna. The total rf power coming out of the sphere
divided by the total rf power into the antenna [sphere] is the antenna
efficiency. There is NO OTHER definition!

Reducing power in the back and side lobes has absolutely NOTHING to do
with efficiency. It has to do with directivity.

Design of a Yagi, traps, conductors, element spacing etc. will produce
variations in gain, directivity, efficiency [variations in losses,
heat]. Practically, the difference in efficiency between a 90% efficient
antenna and a 98% efficient antenna is swamped by variations in the path
loss physics.

I spent years of my life designing rf systems for telemetry from space
vehicles through reentry to a ground station. Data integrity at the
ground station was and still is the dominating requirement. Based on
allowable data error rates, the total path equation required S/N ratios
of 12 dB or more. The solution is a systems solution where the minor
variations in antenna efficiency get lost in the calculations.


Art doesn't care about reality, he thinks he can create a new one which
ignores physics. You are wasting your time.

I am plonking this thread, and art.

tom
K0TAR

Yagi efficiency
 

Hi Art

If this was a car news group I'd realize that you have left me in your
dust. I just cant keep up with you. I thought I understood antennas and
I even thought I could design them. But, I dont even know the meaning of
the words you use, and I am too lazy to study and learn about things like
"emission of flux".
I had designed and built some Yagi arrays that worked pretty but I was
never aware that I detuned any of their elements. I just thought they were
as efficient as any other array of similar size.
It is obvious to me that I'll never understand why those Yogis are
considered inefficient.

Jerry





"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




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

Yagi efficiency
 

Well I obviously misunderstood the question
What I have done is to make elements resonant with possesion of
different lengths
This is not that unusual with antennas. Now 'how' you make a shorter
element resonant at the same frequency is where we part. I would make
the element resonant by the addition of nearby elements not by adding a
constant like an inductance ,so obviously I have not plotted anything
according to what you are pointing to



John Smith wrote:
art wrote:
Well now I am not sure what you want plotting if you are making the
reflector resonant
other than the design frequency of the array.
JS


Art:

No, the reflector would remain the same ~5% longer (electrically and
physically) than the de. And, the director remains physically shorter
than the de, but made resonate with the proper addition of a coil,
somewhere in its length, so as to be made resonate at the same freqs as
the de (or approx. so, since the coil will undoubtedly change some
characteristics from that of the resonate de.

Art, you are rapid losing me here. Either I am not able to see what you
are getting at, or else I suspect you of having some facts or formulas
twisted about here...

Regards,
JS

Yagi efficiency
 

Well I obviously misunderstood the question
What I have done is to make elements resonant with possesion of
different lengths
This is not that unusual with antennas. Now 'how' you make a shorter
element resonant at the same frequency is where we part. I would make
the element resonant by the addition of nearby elements not by adding a
constant like an inductance ,so obviously I have not plotted anything
according to what you are pointing to



John Smith wrote:
art wrote:
Well now I am not sure what you want plotting if you are making the
reflector resonant
other than the design frequency of the array.
JS


Art:

No, the reflector would remain the same ~5% longer (electrically and
physically) than the de. And, the director remains physically shorter
than the de, but made resonate with the proper addition of a coil,
somewhere in its length, so as to be made resonate at the same freqs as
the de (or approx. so, since the coil will undoubtedly change some
characteristics from that of the resonate de.

Art, you are rapid losing me here. Either I am not able to see what you
are getting at, or else I suspect you of having some facts or formulas
twisted about here...

Regards,
JS

Yagi efficiency
 

I wouldn't worry about that, you have made them and they work in a
manner that satisfies you what more could you want of an antenna?
Remember an extra DB in performance lookes like an achievement when
dealing with design but the fact is you would not see a difference if
you upgraded your antenna, so efficiency is not a factor for you as a
user. Increasing efficiency is just one small step that when added to
other small steps it gets everybodies attention it is at that point you
will take the step to upgrade. Enjoy and remember efficiency is a very
relevant term as it could be refering to something that is desired but
impossible to improve
Art

Jerry Martes wrote:
Hi Art

If this was a car news group I'd realize that you have left me in your
dust. I just cant keep up with you. I thought I understood antennas and
I even thought I could design them. But, I dont even know the meaning of
the words you use, and I am too lazy to study and learn about things like
"emission of flux".
I had designed and built some Yagi arrays that worked pretty but I was
never aware that I detuned any of their elements. I just thought they were
as efficient as any other array of similar size.
It is obvious to me that I'll never understand why those Yogis are
considered inefficient.

Jerry





"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




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

Yagi efficiency
 

art wrote:
Tom it is no good plonking me for what david is saying because he is
not quoting me, in fact some of it is a requote of what he said not me.
I think he is creating a straw man that he can argue with, is that what
you call reality? He has spent most of his time in space and I believe
him

Tom Ring wrote:
Dave wrote:

SNIPPED


Art:

First, you must learn "theory" (and there IS a reason they term that
THEORY! it is JUST THAT!) the way they learned it, so you can quote it
to them verbatim, else they can't relate, else they are quick to
dismiss. It helps if every once in awhile you say, "I know the accepted
way of thinking says this, or that... but what about this other, or that
other?" (yanno what I mean?)

Then you can really begin "thinking."

However, that is not all bad, it gives common ground so we ALL can
communicate on a level which gives some understanding and purpose,
perhaps to a final goal ...

.... and beware, there are "other thinkers" here, they just choose to
remain hidden and duck the wrath and arrows of the "rote-ly educated."

JS

Yagi efficiency
 

Well I obviously misunderstood the question
What I have done is to make elements resonant with possesion of
different lengths
This is not that unusual with antennas. Now 'how' you make a shorter
element resonant at the same frequency is where we part. I would make
the element resonant by the addition of nearby elements not by adding a
constant like an inductance ,so obviously I have not plotted anything
according to what you are pointing to



John Smith wrote:
art wrote:
Well now I am not sure what you want plotting if you are making the
reflector resonant
other than the design frequency of the array.
JS


Art:

No, the reflector would remain the same ~5% longer (electrically and
physically) than the de. And, the director remains physically shorter
than the de, but made resonate with the proper addition of a coil,
somewhere in its length, so as to be made resonate at the same freqs as
the de (or approx. so, since the coil will undoubtedly change some
characteristics from that of the resonate de.

Art, you are rapid losing me here. Either I am not able to see what you
are getting at, or else I suspect you of having some facts or formulas
twisted about here...

Regards,
JS

Yagi efficiency
 

"art" wrote in message
oups.com...
From a theoretical way of getting at the answer it seems
a logical way of proceding. So now to the rest of the task.1 how do we
determine volumes that you talk about that are a result of deflection 2
How do we determine
radiation that was cancelled or neutralised and 3 How do you determine
the radiation volume created by ground reflection so we can work back
to search for ground losses. That last one really bothers me as I have
never got a good handle on the contribution of ground reflection to any
particular part of the radiation envelope.

Art



Denny wrote:
For those who wish to actually learn and not just insult each other,
get a calculator, learn how to calculate Cosine Theta a trivial math
problem that any 9th grader can be taught in 5 minutes flat, get a BIG
piece of paper reason to come, and actually calculate the shape and
vector length of the lobes of a two element Yagi-Uda antenna... Do the
calculation in both the horizonal and vertical planes... From that you
can calculate the volume of each lobe, which is proportional to the
percentage of power in each lobe... From that number you can very
simply calculate what percentage went into the lobes you prefer and
what went in the lobes you don't prefer...

Now, the reason for the BIG piece of paper... The antenna patterns you
see on the screen with EZNEC, or in the antenna handbooks, are
logarithmic, not linear and there are flavors to them, ARRL, linear
logarithmic, modified logarithmic... So, the patterns are
distorted... Why is that? Because if they were linear and the front
lobe and the rear lobe are to the same scale the front lobe will take
up the entire length of the screen/paper and the rear lobe will need a
magnifying glass to be seen... A rear lobe that is 20dB down from the
front lobe is down by the power ratio of 100... So, if your forward
lobe calculates out to be 10 inches long, the rear lobe will be be 1/10
of an inch.... I'll let you figure out the size of a lobe that is 30dB
down (get out your microscope)

For those who want to review do a search on Joseph Reisert, who has
published numerous writings on antennas and patterns... There many are
others also, but Joe is published on the web, and very readable...

cheers ... denny / k8do

The radiation IS NOT cancelled or Neutralized. You need to learn more about
what is going on with an antenna. I suggest you do some serious reading,
actually reading with an open mind and not reading trying to find little
phrases that seem to you to prove your beliefs. It should be fairly obvious
that if an antenna worked by neutralization or cancelation that it would
take more energy to cancel out radiation in the undesired direction of a
yagi than is available in the desired direction. Therefore a Yagi or any
other antenna does not work by cancellation.

I gues I could express this a lot better but its late and whats the use.