Determining Total Gain of an Antenna
 

art wrote:
Ofcourse Cecil you also have muddled up things by introducing
your favorite subject but I suspect you did that because of
that rebel approach as opposed to confusing the poster(grin)

Actually I have been moving and haven't been keeping
up with a lot of threads. I was responding only to
the content of Richard H.'s posting. But it seems
obvious to me that the way to add voltage vectors
is to use vector addition. The way to add voltage
phasors is to use phasor addition.
--
73, Cecil http://www.w5dxp.com

Determining Total Gain of an Antenna
 

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

Determining Total Gain of an Antenna
 

"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

Determining Total Gain of an Antenna
 

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

Determining Total Gain of an Antenna
 

On May 30, 10:47 am, art wrote:
On 29 May, 19:47, (Richard Harrison) wrote:

Matt Brenenman wrote:

"When I think of how a field induces a voltage, I think of voltage as
being proportional to norm of the field."

OK. Terman wrote on page 2 of his 1955 opus:
"The strength of the wave measures in terms of microvolts per meter of
stress in space is also exactly the same voltage that the magnetic flux
of the wave induces in a conductor 1 m long when sweeping across this
conductor with the velocity of light."

Since Matt mentions circular polarization, one of the problems on page
50 in Kraus` 3rd edition of "Antennas" is notable. It states:
"1-16-2 More power in C.P. 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 for both waves. This means that
the medium can handle twice as much power before breakdown with circular
polarization (CP) than with linear polarization (LP)."

Best regards, Richard Harrison, KB5WZI

Richard,
I am trying to decipher the above so my comments may well not be
relavent to what you are actually saying.
It is a given that far field circular polarisation
results in a 3 db loss with respect to radiation compared to other
polarisations. But one cannot from this assume that radiation
from a radiator changes with respect to the designed polarization.
When current is applied to a radiator in a time varient condition
the vectors involved cannot change.
The three phases of radiation are current application and electron
emmission,formation of the near field and finally formation of the
far field.
I fail to see how vectors formed in the initial stage which can
be seen as a Poyntings explanation changes or depends upon
future formations of the ensueing radiation waves.
Since the poster is interested in mathematicalanalysis of radiation
he must obviously realise that the Laws of Conservation must be held
and it woulkd appear that some confusion has been injected into his
problem.
Art

Thank you for the responses. I've been to an out of town symposium the
last week, and I haven't had time yet to sit down and think about them
much. I'll look at the texts suggested and then perhaps I can make a
considered reply ;).

Thank you once again,

M