art wrote:
So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Art, maybe you should take time to study "dimensional
analysis". It really opened my eyes a half-century ago.
If you want to divide joules by amps, just put the most
elementary dimensions into the division and see what
are the results.
--
73, Cecil http://www.w5dxp.com

On 10 May, 15:24, Cecil Moore wrote:
art wrote:
So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Art, maybe you should take time to study "dimensional
analysis". It really opened my eyes a half-century ago.
If you want to divide joules by amps, just put the most
elementary dimensions into the division and see what
are the results.
--
73, Cecil http://www.w5dxp.com

On 10 May, 15:24, Cecil Moore wrote:
art wrote:
So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Art, maybe you should take time to study "dimensional
analysis". It really opened my eyes a half-century ago.
If you want to divide joules by amps, just put the most
elementary dimensions into the division and see what
are the results.
--
73, Cecil http://www.w5dxp.com

Cecil, this augument is an old one. I remember Roy really get his
knickers
in a twist when some of the group referred to F/B db. Sometimes you
just have to go with the flow. Many antenna experts have given up on
this group
since they could not or would not do what you have done succesfully
i.e. record posts in response to everybody and anybody. I prefer to
provide a subject where I know that those who visualise themselves as
pro's in the business of antennas expose their limitations to the
World. It really is like politics everybody can spout about what is
incorrect but few can offer an explanation of what is correct. Many
just evoke memories of what they did in yesteryearat work or what they
achieved in memory tests at exams when the truth is that the
experience that they refer to is ones that they repeated year after
year but never where they have advanced in technical proweress from
times over 50 years ago, as if the World has stood still. Give me
strength. We really are just a bunch of old men speaking of the old
times with the same stories time over time again as if we are at a
coffee break and where the majority moved over years ago from CB radio
with appliance and technical mentality learned on channel 13 or what
ever it was. Seems like for some over time see their experience of
employment grew to the proportions of giants in industry as they grew
older when in fact they are living in illusions.
Thanks for the free advice as to what I should do but I already have a
life.
Art

art wrote:
On 10 May, 14:41, (Richard Harrison) wrote:
Art wrote:

"For my interest, what is the unit that must be used for front to back
ratio of a directive antenna?"

I must be an idiot for venturing an answer, but ratios can be just
numbers, but numbers have origins. If radiated power in one direction is
twice that in another (reference), we can say it has a directive gain of
two or we can say it has a 3 dB gain. Front to back ratios have the same
origins and units. For legitimacy, Terman says on page 871 of his 1955
opus:
"The directive gain can be expressed either as a power ratio, or in
terms of the equivalent number of decibels.

Best regards, Richard Harrison, KB5WZI

So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Example:

Forward gain = 12db
Reverse gain = 2db

Front to back ratio = 12db/2db = 6; no units as they cancel.

5th grade mathematics.

--
Jim Pennino

Remove .spam.sux to reply.

On 10 May, 13:58, "Frank's"
wrote:
"Cecil Moore" wrote in message

t...





art wrote:
I am aware that the impedance of a particular
atmosphere is 377 ohms but that is certainly not a ratio.

From:http://whatis.techtarget.com/definit...845268,00.html

Frank, you got my attention when you pointed to the above link.
I read it a few times and 377 ohms was refered to as Zo. I can't find
any reference
that states Zo is a ratio. Did you intend to point to another link
that specifically points
to Zo is a ratio? Surely you are not following in the steps of others
where anything can be written
right or wrong as long as it creats an augument or distress? You
disapoint me!
Some in this group are already thinking it is legal for a ratio to
have units assigned
because of the inference that the link say's it's so which is an
untruth and
you are perpetuating the spread of untruths. This is similar to
another untruth
that is being perpetuated with respect to photons just because one
person
it be so stated. It is getting to the point that if you read it on the
net don't believe it
unless it can be verified

Art




Mathematically, the Zo of free space is equal to the square root of the
ratio of the permeability of free space (µo) in henrys per meter (H/m) to
the permittivity of free space (o) in farads per meter (F/m):

Zo = (µo/o)1/2

= [(1.257 x 10-6 H/m)/(8.85 x 10-12 F/m)]1/2

= 377 ohms (approximately)

The exact value of the Zo of free space is 120 pi ohms, where pi is the
ratio of the circumference of a circle to its diameter.
--
73, Cecil, w5dxp.com

Also the ratio of E/H. [(V/m)/(A/m)] = [ohms].

Frank- Hide quoted text -

- Show quoted text -

Richard Harrison wrote:
Art wrote:
"For my interest, what is the unit that must be used for front to back
ratio of a directive antenna?"

I must be an idiot for venturing an answer, but ratios can be just
numbers, but numbers have origins. If radiated power in one direction is
twice that in another (reference), we can say it has a directive gain of
two or we can say it has a 3 dB gain. . .

Forgive me for picking a nit here, but the front/back ratio is the ratio
of radiated *field strength* or radiated *power density*, not radiated
power. Strictly speaking, there is zero power radiated in any single
direction.

Roy Lewallen, W7EL

On 10 May, 16:55, wrote:
art wrote:
On 10 May, 14:41, (Richard Harrison) wrote:
Art wrote:

"For my interest, what is the unit that must be used for front to back
ratio of a directive antenna?"

I must be an idiot for venturing an answer, but ratios can be just
numbers, but numbers have origins. If radiated power in one direction is
twice that in another (reference), we can say it has a directive gain of
two or we can say it has a 3 dB gain. Front to back ratios have the same
origins and units. For legitimacy, Terman says on page 871 of his 1955
opus:
"The directive gain can be expressed either as a power ratio, or in
terms of the equivalent number of decibels.

Best regards, Richard Harrison, KB5WZI
So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Example:

Forward gain = 12db
Reverse gain = 2db

Front to back ratio = 12db/2db = 6; no units as they cancel.

5th grade mathematics.

--
Jim Pennino

Remove .spam.sux to reply.- Hide quoted text -

- Show quoted text -

Not so fast! It would appear that we have some real experts in the
group
that would disagree with you on this, probably because they judge
your
performance on your postings and not on the extensive experiences.
I suspect that some did not go along with your lengthy verbal
launchings
on the illigitimacy of adding a time metric to Gaussian law
regardless
of mathematical proof given, You were not able to pinpoint a
mathematical error and relied on the word "can't" around which
many of your utterings revolve. There was a fable written about
a person who called "wolf" once to often who had nobody to
blame but himself. If you make a habit of lying then the truth
get's a hard time in obtaining belief.

(Richard Harrison) wrote in news:18308-
:

Art wrote:
"For my interest, what is the unit that must be used for front to back
ratio of a directive antenna?"

I must be an idiot for venturing an answer, but ratios can be just
numbers, but numbers have origins. If radiated power in one direction
is
twice that in another (reference), we can say it has a directive gain
of
two or we can say it has a 3 dB gain. Front to back ratios have the
same
origins and units. For legitimacy, Terman says on page 871 of his 1955
opus:
"The directive gain can be expressed either as a power ratio, or in
terms of the equivalent number of decibels.

This seems to introduce a new concept of "directive gain", which isn't
Directivity as it is commonly used / understood, and it isn't Gain as it
is commonly used / understood. It also seems to be based on a flexible
reference (being "another" direction).

What is wrong with the concept that Directivity (either the maximum, or
in a specific direction) is the ratio of the power density (more
correctly) in that case to the power density averaged over all
directions, and that Gain=Directivity/Loss.

Richard, you seem to have used a textbook to define something that it
didn't.

Owen

art wrote:
On 10 May, 16:55, wrote:
art wrote:
On 10 May, 14:41, (Richard Harrison) wrote:
Art wrote:

"For my interest, what is the unit that must be used for front to back
ratio of a directive antenna?"

I must be an idiot for venturing an answer, but ratios can be just
numbers, but numbers have origins. If radiated power in one direction is
twice that in another (reference), we can say it has a directive gain of
two or we can say it has a 3 dB gain. Front to back ratios have the same
origins and units. For legitimacy, Terman says on page 871 of his 1955
opus:
"The directive gain can be expressed either as a power ratio, or in
terms of the equivalent number of decibels.

Best regards, Richard Harrison, KB5WZI
So it is now the norm not to cancel units of measurement in physics?
Woe is me. Free speech takes on a new meaning for some but not
acceptable from others meaning a term for a formula can now be called
a ratio with units of one's choice. Still, this is amateur radio after
all, it does not have to follow professional standards as most was
learned in the CB era

Example:

Forward gain = 12db
Reverse gain = 2db

Front to back ratio = 12db/2db = 6; no units as they cancel.

5th grade mathematics.

--
Jim Pennino

Remove .spam.sux to reply.- Hide quoted text -

- Show quoted text -

Not so fast! It would appear that we have some real experts in the
group

People beyond 5th grade math? I expect most posters are.

snip rambling babble

--
Jim Pennino

Remove .spam.sux to reply.

I am aware that the impedance of a particular
atmosphere is 377 ohms but that is certainly not a ratio.

From:http://whatis.techtarget.com/definit...845268,00.html

Frank, you got my attention when you pointed to the above link.
I read it a few times and 377 ohms was refered to as Zo. I can't find
any reference
that states Zo is a ratio. Did you intend to point to another link
that specifically points
to Zo is a ratio? Surely you are not following in the steps of others
where anything can be written
right or wrong as long as it creats an augument or distress? You
disapoint me!
Some in this group are already thinking it is legal for a ratio to
have units assigned
because of the inference that the link say's it's so which is an
untruth and
you are perpetuating the spread of untruths. This is similar to
another untruth
that is being perpetuated with respect to photons just because one
person
it be so stated. It is getting to the point that if you read it on the
net don't believe it
unless it can be verified.

I think you are confusing a posting by Cecil. Anyway, quoting
from "Engineering Electromagnetics" by Nathan Ida, 2nd ed. p 743:
"....the reference field is E (an arbitrary choice used in
electromagnetics as a convention). Thus we define the ratio between
Ex(z) and Hy(z) as eta = Ex(z)/Ey(z) = ...... sqrt(mu/epsilon) [ohms]
This quantity is an impedance because the electric field intensity is
given in [V/m] and the magnetic field intensity is given in [A/m].
The quantity eta is called the intrinsic impedance or wave impedance
of the material.....".

Frank