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