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