On 30 May, 10:21, (Richard Harrison) wrote:
Art wrote:

"The three phases of radiation are the current application and the
electron emission, formation of the near field and finally formation of
the far field."

The questioner asked: "If I want to compute the voltage induced on the
antenna by the field, do I add the two E field components or do I
compute the norm of the vector on the RHS of eqn (II) ?"

Art replied:
"Gain can mean many things."

Terman defines on page 870 of his 1955 opus:
"The extent of such concentration relative to that of some standard
antenna, termed the directive gain, is defined quantitatively as the
ratio of power that must be radiated by the comparison antenna to
develop a particular field strength in the direction of maximum
radiation to the power that must be radiated by the directional antenna
system to obtain the same field strength in the same direction."

Kraus shows how to handle arrays of point sources. All the math is
included.

Kraus wrote on page 12 of the 3rd edition of "Antennas":
"Antennas convert electrons to photons or vice versa."

If the questioner draws his information from Terman and Kraus, he won`t
err.

Best regards, Richard Harrison, KB5WZI

Richard, you evoked the phrase Poyntings vector which is an excellent
point to start
with respect to the formation of radiation especially with respect to
mathematical analysis
I iknow that you mentioned a couple of books to add weight to your
response
but a circular polarised wave has no place what so ever in a
mathematical analysis
of Poyntings vector. Yes we all know that there is a 3db difference
when looking
at the gain of a circular polarised antenna as well as many other
facts with
respect to antennas but you invoked "poyntings vector" where flux
movement
is used as a mathematical beginning. I am not disputing anything that
is
in the books that you often refer to but only how you interprete the
written word
to add authority to your analysis where it has no place.
I say again, since you evoked the term Poyntings vector in response to
mathematical
question that is no place to insert polarisation differences that may
take place
not in the Poynting areana but at a much later stage in radiation.
However, since you muddled things up by introducing Pointings vector
and coupled it
to circular polarisation maybe you can enlarge how this vector changes
with respect
to the choice of polarisation. Don't waffle by reciting books and
facts written
in books that don't relate to the subject at hand but give an
explanation to
the poster who acknoweledges that he is new to antennas but not to the
mathematical
aspects of same.
He is asking for assistance and not a measure of your personal
knoweledge or the books that you have or what you believe the
intent of the author is in what he states.
Regards
Art

Art wrote:
"Richard you evoked the phrase Poynting`s vector which is an excellent
place to start---etc,"

I appreciate being credited by Art with evoking the Poynting vector, but
I wasn`t first.

The priginal poster wrote:
"Now I have an incident E field(which happens to be a RHCP, that I can
write as a plane wave: etc."

Art then responded:
"Matt, Gain can mean many things. If you can back up on your vector
approach, a look at Poynting`s theorem would be a good start."

I posted next, recommending Terman and Kraus to the self-proclaimed
"Newbie" I suggested he look at one of Kraus` assigned problems, no.
1-16-2 which asks the student to:
"Show that the average Poynting vector of a circularly polarized wave is
twice that of a linearly polarized wave if the maximum electric field E
is the same in both waves."

Everyone will say that`s obvious as the polarized constituent waves in
CP are at right angles and thus are independent. But, Kraus goes through
all the steps and supplies all the math to enable the student to make
the proof. It`s like a geometry proof of the obvious but it is still
informative to work the problens.

I am lazy and rhought that these great professors do a great job of
explaining everything accurately and succinctly. I could never hope to
do it so well. It is a job for the student himself to follow the
explanation and I merely pointed to those I think are the best.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Art wrote:
"Richard you evoked the phrase Poynting`s vector which is an excellent
place to start---etc,"

I appreciate being credited by Art with evoking the Poynting vector, but
I wasn`t first.

The priginal poster wrote:
"Now I have an incident E field(which happens to be a RHCP, that I can
write as a plane wave: etc."

Art then responded:
"Matt, Gain can mean many things. If you can back up on your vector
approach, a look at Poynting`s theorem would be a good start."

I posted next, recommending Terman and Kraus to the self-proclaimed
"Newbie" I suggested he look at one of Kraus` assigned problems, no.
1-16-2 which asks the student to:
"Show that the average Poynting vector of a circularly polarized wave is
twice that of a linearly polarized wave if the maximum electric field E
is the same in both waves."

Everyone will say that`s obvious as the polarized constituent waves in
CP are at right angles and thus are independent. But, Kraus goes through
all the steps and supplies all the math to enable the student to make
the proof. It`s like a geometry proof of the obvious but it is still
informative to work the problens.

I am lazy and rhought that these great professors do a great job of
explaining everything accurately and succinctly. I could never hope to
do it so well. It is a job for the student himself to follow the
explanation and I merely pointed to those I think are the best.

Best regards, Richard Harrison, KB5WZI


Great idea Richard, I never understood AM until I had to go through the
math. I probably still couldnt explain it to someone but I can dig out my
old notebook and take them through the math. That is if I can still find it.
They say 3 moves is the same as a fireand Ive been through 5.

Jimmie

On 30 May, 19:00, "Jimmie D" wrote:
"Richard Harrison" wrote in message

...





Art wrote:
"Richard you evoked the phrase Poynting`s vector which is an excellent
place to start---etc,"

I appreciate being credited by Art with evoking the Poynting vector, but
I wasn`t first.

The priginal poster wrote:
"Now I have an incident E field(which happens to be a RHCP, that I can
write as a plane wave: etc."

Art then responded:
"Matt, Gain can mean many things. If you can back up on your vector
approach, a look at Poynting`s theorem would be a good start."

I posted next, recommending Terman and Kraus to the self-proclaimed
"Newbie" I suggested he look at one of Kraus` assigned problems, no.
1-16-2 which asks the student to:
"Show that the average Poynting vector of a circularly polarized wave is
twice that of a linearly polarized wave if the maximum electric field E
is the same in both waves."

Everyone will say that`s obvious as the polarized constituent waves in
CP are at right angles and thus are independent. But, Kraus goes through
all the steps and supplies all the math to enable the student to make
the proof. It`s like a geometry proof of the obvious but it is still
informative to work the problens.

I am lazy and rhought that these great professors do a great job of
explaining everything accurately and succinctly. I could never hope to
do it so well. It is a job for the student himself to follow the
explanation and I merely pointed to those I think are the best.

Best regards, Richard Harrison, KB5WZI

Great idea Richard, I never understood AM until I had to go through the
math. I probably still couldnt explain it to someone but I can dig out my
old notebook and take them through the math. That is if I can still find it.
They say 3 moves is the same as a fireand Ive been through 5.

Jimmie- Hide quoted text -

- Show quoted text -

Richard,
First I will apologise for not deciphering your posting correctly
or recognising that the statement was in fact in the form of a
question.
For myself I still have the problem of associating Poyntings
vector in association with fields and waves outside the circle
as it were and is a gap that I need to fill for myself with some
indepth reading. Hopefully the original poster does not have
the same problem that I have and is satisfied with your response.
Regards
Art