My question(s):

For an example, on the 10 meter band:
If I take a 28" whip and mount it at the end of helical wound coil (wound on
1" diameter form), where the "wire length" of the coil, PLUS, the length of
the whip (28" + coil wire length) is equal to 1/2 wavelength (electrical
length)--BUT, the overall physical length of the antenna (top, tip of whip
to base of helical wound coil) is 1/4 wavelength, what would the radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be totally
unrelated to either?

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive? What would be the best way to provide
a match to 50 ohm coax from such an antenna?

What software is available to model such an antenna?

Thanks in advance,
warmest regards

If you wind, say, 100 inches of wire into a coil, it doesn't act the
same as 100 inches of straight wire. And no two different coils wound
from 100 inches of wire will act the same. A coil's radiation
characteristics are very nearly the same as for a wire the outside
diameter and length of the coil, not the length of the wire it's made
from. And the inductance of the coil is dictated by the length, pitch,
number of turns, and diameter of the coil, not the length of the wire
it's wound from. So your question can't be answered unless you tell us
the diameter of the coil and any two of length, pitch, and number of
turns; or the length and diameter of the coil and its inductance at the
frequency at which it's being used.

Roy Lewallen, W7EL

John Smith wrote:
My question(s):

For an example, on the 10 meter band:
If I take a 28" whip and mount it at the end of helical wound coil (wound on
1" diameter form), where the "wire length" of the coil, PLUS, the length of
the whip (28" + coil wire length) is equal to 1/2 wavelength (electrical
length)--BUT, the overall physical length of the antenna (top, tip of whip
to base of helical wound coil) is 1/4 wavelength, what would the radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be totally
unrelated to either?

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive? What would be the best way to provide
a match to 50 ohm coax from such an antenna?

What software is available to model such an antenna?

Thanks in advance,
warmest regards

OK, if you notice in my post wire length is in quotes, i.e. "wire length."
In the example, it is a given that this length resonates at 1/2 wave along
with the combined length of the whip (hence, electrical 1/2 wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire minus
28 inches which is necessary to be a resonate 1/2 wave, AND this is divided
over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil length--the
pitch is calculated from the coil length ((1/4 wave @ 10 meters) - 28
inches) and the wire lenght divided by pi (number of turns) spread out over
the coil ENTIRE length. And, of course, coil length plus whip length is a
1/4 wave.

If you refer back to my original post, you will see all of this IS there...

However, critical analysis is a wise beginning of any quest for answers.

Regards



"Roy Lewallen" wrote in message
...
If you wind, say, 100 inches of wire into a coil, it doesn't act the same
as 100 inches of straight wire. And no two different coils wound from 100
inches of wire will act the same. A coil's radiation characteristics are
very nearly the same as for a wire the outside diameter and length of the
coil, not the length of the wire it's made from. And the inductance of the
coil is dictated by the length, pitch, number of turns, and diameter of
the coil, not the length of the wire it's wound from. So your question
can't be answered unless you tell us the diameter of the coil and any two
of length, pitch, and number of turns; or the length and diameter of the
coil and its inductance at the frequency at which it's being used.

Roy Lewallen, W7EL

John Smith wrote:
My question(s):

For an example, on the 10 meter band:
If I take a 28" whip and mount it at the end of helical wound coil (wound
on
1" diameter form), where the "wire length" of the coil, PLUS, the length
of
the whip (28" + coil wire length) is equal to 1/2 wavelength (electrical
length)--BUT, the overall physical length of the antenna (top, tip of
whip
to base of helical wound coil) is 1/4 wavelength, what would the
radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be totally
unrelated to either?

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive? What would be the best way to
provide
a match to 50 ohm coax from such an antenna?

What software is available to model such an antenna?

Thanks in advance,
warmest regards

"John Smith" wrote in message
...
OK, if you notice in my post wire length is in quotes, i.e. "wire length."
In the example, it is a given that this length resonates at 1/2 wave along
with the combined length of the whip (hence, electrical 1/2 wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire
minus
28 inches which is necessary to be a resonate 1/2 wave, AND this is
divided
over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil
length--the
pitch is calculated from the coil length ((1/4 wave @ 10 meters) - 28
inches) and the wire lenght divided by pi (number of turns) spread out
over
the coil ENTIRE length. And, of course, coil length plus whip length is a
1/4 wave.

If you refer back to my original post, you will see all of this IS
there...

However, critical analysis is a wise beginning of any quest for answers.

Regards
Roy's answer is right on the mark.
The length of the wire is of no help in answering the question.
You are confusing mechanical lengths with electrical lengths.
Dale W4OP

It seems to me that the guy was trying to help, so no need to "bite the hand
that feeds",
old chap !! Better to cultivate him, than **** him off, however technically
correct you might be ......

Nick



"Dale Parfitt" wrote in message
news:hMz%d.9885$b_6.3645@trnddc01...

"John Smith" wrote in message
...
OK, if you notice in my post wire length is in quotes, i.e. "wire length."
In the example, it is a given that this length resonates at 1/2 wave along
with the combined length of the whip (hence, electrical 1/2 wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire
minus
28 inches which is necessary to be a resonate 1/2 wave, AND this is
divided
over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil
length--the
pitch is calculated from the coil length ((1/4 wave @ 10 meters) - 28
inches) and the wire lenght divided by pi (number of turns) spread out
over
the coil ENTIRE length. And, of course, coil length plus whip length is a
1/4 wave.

If you refer back to my original post, you will see all of this IS
there...

However, critical analysis is a wise beginning of any quest for answers.

Regards
Roy's answer is right on the mark.
The length of the wire is of no help in answering the question.
You are confusing mechanical lengths with electrical lengths.
Dale W4OP

On Sun, 20 Mar 2005 18:26:42 -0800, "John Smith"
wrote:
what would the radiation pattern of such an antenna be?

Hi John,

This appears to be a difficult question to answer, if for only all of
the extraneous details. Patterns are determined by the physical size
in relation to wavelength. It is all about geometry and distances
between what are called current nodes - what you describe has no s in
the node(s), so the geometry (pattern) is still quite simple.

Obtain a free copy of EZNEC to confirm.

73's
Richard Clark, KB7QHC

The original post is a math problem--its "solution" is an antenna. It is
structured as a "word problem", as opposed to a math problem written using
digits and numbers--for the most part--only coil diameter, whip length and
wavelength (both physical and electrical) are expressed as numbers. Most
will be familiar with this from high school or college mathematics.
However, since this alone seems to be such a matter of confusion, let's look
at the problem and rely on more numeric means of expression-using only the
information from my first post.



1) top whip length = 28 inches

2) coil diameter = 1 inch

3) physical coil length = (1/4 wavelength - 28 inches)

4) antenna physical length = 28 inches + coil length

5) "wire length"(whip + coil wire length) = electrical ½ wavelength

6) number of turns = (wire length / (pi(3.14159) * coil diameter(1
inch)))

= (wire length / 3.14159 inches)

7) pitch = number of turns spread/spaced over the ENTIRE (helical) coil
length

8) antenna is end fed at the base, EFWHA-a vertical monopole

9) The antenna's physical length is ¼ wave on 10 meters but, is a ½
wavelength electrical length on 10 meters.



NOTE: Please feel free to critique/correct any errors I have made in the
above, no offense will be taken (but, arguments may be posed!)-indeed, this
stands in regard to all my posts.



My questions, defined in greater detail, were/a



1) What would the radiation pattern of such an antenna be-favor ¼ wave?
Favor ½ wave? A hybrid pattern of ¼ and ½? Or, would it be unique pattern
onto this antenna alone, and only vaguely reminiscent to one or the other,
or both? (And arrived at by math, charts, measurement or other means which
provide "proofs."

2) Would this antenna display a reactance which is capacitive or inductive,
or purely resistive (and what proof(s) confirms this?)

3) What would the impedance of this antenna be? (Even a ballpark
figure-within 5%-10% but, derived though math, chart or direct
measurement-NOT a guess?)

4) What method of matching this antenna to 50 ohm coax would be "best?"
(Capacitive hats, l-network, pi-network, balun (unun in this case), ¼ wave
line, combinations of these schemes, etc.?)

5) Is there software capable of modeling such an antenna constructed under
these specifications (I have mmana but am unable to grasp how it could be
used for such a design?)



Certainly no disrespect was meant in my response to Ray's comments. Indeed,
if I "miss-treat" individuals I don't expect I will get ANY interaction from
them-this is NOT my purpose or intent! And, if you re-read my second post,
I complement him on his critique of the problem and his analytical powers.
In my neck of America, if someone attempts to set up conflict over verbal or
text exchanges, we generally consider him/her to be a "chit stirrer."



If my intent is NOT clear, let me try again: This is simply an excursion
into the exploration of an antenna design and its' properties. If you are
intent to read other goals into my posts-you are on your own!



I totally expect only those with knowledge, skills and investigative minds
to bother in this endeavor and, some will not even see reason to ask these
questions at all-one can probably be purchased off a shelf-somewhere in the
world.



Warmest regards



"nick smith" wrote in message
...
It seems to me that the guy was trying to help, so no need to "bite the
hand
that feeds",
old chap !! Better to cultivate him, than **** him off, however
technically
correct you might be ......

Nick



"Dale Parfitt" wrote in message
news:hMz%d.9885$b_6.3645@trnddc01...

"John Smith" wrote in message
...
OK, if you notice in my post wire length is in quotes, i.e. "wire
length."
In the example, it is a given that this length resonates at 1/2 wave
along
with the combined length of the whip (hence, electrical 1/2
wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire
minus
28 inches which is necessary to be a resonate 1/2 wave, AND this is
divided
over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil
length--the
pitch is calculated from the coil length ((1/4 wave @ 10 meters) - 28
inches) and the wire lenght divided by pi (number of turns) spread out
over
the coil ENTIRE length. And, of course, coil length plus whip length is
a
1/4 wave.

If you refer back to my original post, you will see all of this IS
there...

However, critical analysis is a wise beginning of any quest for
answers.

Regards
Roy's answer is right on the mark.
The length of the wire is of no help in answering the question.
You are confusing mechanical lengths with electrical lengths.
Dale W4OP

The use of "wire length" to describe the antenna impedance made it
diffiicult to understand what you were asking, and certainly deflected
my thinking. If you had only said that the coil had the inductance
necessary to make the antenna half-wave resonant (or antiresonant), it
would have been more clear. On re-reading it, I see that it's what you
meant, and it's what you did say in a slightly unconventional manner. So
that gives enough information for at least some general answers to your
questions:

to base of helical wound coil) is 1/4 wavelength, what would the
radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be
totally
unrelated to either?

It would have a pattern very similar to a quarter wave vertical, not a
half wave.

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive?

The resistance would be high, on the order of a couple of thousand ohms
or more. If the coil resonantes the antenna, the feedpoint reactance, by
definition, is zero. However, a slight deviation of the frequency from
resonance will result in a fairly large reactance. It will be inductive
below resonance and capacitive above.

What would be the best way to
provide
a match to 50 ohm coax from such an antenna?


Connect one conductor of the feedline to the antenna base, and tap up
the helix with the other until a good match is achieved. This requires
that the antenna be resonated with the coil.

What software is available to model such an antenna?


EZNEC is able to do it. The demo program could be used to make an
approximate model with the inductor modeled as a number of lumped loads
along the wire. With the standard or plus programs you can model the
inductor directly as a wire helix. I develop and sell EZNEC, so I'll
leave it to others to recommend other programs -- I believe there are
several which can do the job.

Roy Lewallen, W7EL

John Smith wrote:
OK, if you notice in my post wire length is in quotes, i.e. "wire length."
In the example, it is a given that this length resonates at 1/2 wave along
with the combined length of the whip (hence, electrical 1/2 wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire minus
28 inches which is necessary to be a resonate 1/2 wave, AND this is divided
over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil length--the
pitch is calculated from the coil length ((1/4 wave @ 10 meters) - 28
inches) and the wire lenght divided by pi (number of turns) spread out over
the coil ENTIRE length. And, of course, coil length plus whip length is a
1/4 wave.

If you refer back to my original post, you will see all of this IS there...

However, critical analysis is a wise beginning of any quest for answers.

Regards



"Roy Lewallen" wrote in message
...

If you wind, say, 100 inches of wire into a coil, it doesn't act the same
as 100 inches of straight wire. And no two different coils wound from 100
inches of wire will act the same. A coil's radiation characteristics are
very nearly the same as for a wire the outside diameter and length of the
coil, not the length of the wire it's made from. And the inductance of the
coil is dictated by the length, pitch, number of turns, and diameter of
the coil, not the length of the wire it's wound from. So your question
can't be answered unless you tell us the diameter of the coil and any two
of length, pitch, and number of turns; or the length and diameter of the
coil and its inductance at the frequency at which it's being used.

Roy Lewallen, W7EL

John Smith wrote:

My question(s):

For an example, on the 10 meter band:
If I take a 28" whip and mount it at the end of helical wound coil (wound
on
1" diameter form), where the "wire length" of the coil, PLUS, the length
of
the whip (28" + coil wire length) is equal to 1/2 wavelength (electrical
length)--BUT, the overall physical length of the antenna (top, tip of
whip
to base of helical wound coil) is 1/4 wavelength, what would the
radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be totally
unrelated to either?

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive? What would be the best way to
provide
a match to 50 ohm coax from such an antenna?

What software is available to model such an antenna?

Thanks in advance,
warmest regards

Well Roy (sorry I mis-spelled your name as Ray in a post above), you are not
the first to bring it to my attention, the fact that my manner and methods
are "unconventional", indeed, some have not been no kind and have referred
to me as eccentric! grin

As I type this, I am downloading a demo of your EZNEC program. I will spend
a little time with it and see if I can get the hang of it and, how to
describe the antenna problem to it. Quite possibly it will provide me with
answers, or even (and quite hopefully!) provide me with new questions.

Thank you for your time in responding and, if I have offended you, as some
others have pointed out may be the case, I apologize, I am sincere when I
state that was not my purpose...

Warmest regards!

"Roy Lewallen" wrote in message
...
The use of "wire length" to describe the antenna impedance made it
diffiicult to understand what you were asking, and certainly deflected my
thinking. If you had only said that the coil had the inductance necessary
to make the antenna half-wave resonant (or antiresonant), it would have
been more clear. On re-reading it, I see that it's what you meant, and
it's what you did say in a slightly unconventional manner. So that gives
enough information for at least some general answers to your questions:

to base of helical wound coil) is 1/4 wavelength, what would the
radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be
totally
unrelated to either?

It would have a pattern very similar to a quarter wave vertical, not a
half wave.

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive?

The resistance would be high, on the order of a couple of thousand ohms or
more. If the coil resonantes the antenna, the feedpoint reactance, by
definition, is zero. However, a slight deviation of the frequency from
resonance will result in a fairly large reactance. It will be inductive
below resonance and capacitive above.

What would be the best way to
provide
a match to 50 ohm coax from such an antenna?


Connect one conductor of the feedline to the antenna base, and tap up the
helix with the other until a good match is achieved. This requires that
the antenna be resonated with the coil.

What software is available to model such an antenna?


EZNEC is able to do it. The demo program could be used to make an
approximate model with the inductor modeled as a number of lumped loads
along the wire. With the standard or plus programs you can model the
inductor directly as a wire helix. I develop and sell EZNEC, so I'll leave
it to others to recommend other programs -- I believe there are several
which can do the job.

Roy Lewallen, W7EL

John Smith wrote:
OK, if you notice in my post wire length is in quotes, i.e. "wire
length." In the example, it is a given that this length resonates at 1/2
wave along with the combined length of the whip (hence, electrical 1/2
wavelength.)

So, your post, while presenting individual points and your opinions, in
general--seems to answer very little, if any, of the original questions
raised--and certainly cannot be accused of containing any specifics.

The diameter IS stated (1"), the wire length is the lenght of the wire
minus 28 inches which is necessary to be a resonate 1/2 wave, AND this is
divided over (1/4 wave at 10 meters - 28 inches.) to arrive at the coil
length--the pitch is calculated from the coil length ((1/4 wave @ 10
meters) - 28 inches) and the wire lenght divided by pi (number of turns)
spread out over the coil ENTIRE length. And, of course, coil length plus
whip length is a 1/4 wave.

If you refer back to my original post, you will see all of this IS
there...

However, critical analysis is a wise beginning of any quest for answers.

Regards



"Roy Lewallen" wrote in message
...

If you wind, say, 100 inches of wire into a coil, it doesn't act the same
as 100 inches of straight wire. And no two different coils wound from 100
inches of wire will act the same. A coil's radiation characteristics are
very nearly the same as for a wire the outside diameter and length of the
coil, not the length of the wire it's made from. And the inductance of
the coil is dictated by the length, pitch, number of turns, and diameter
of the coil, not the length of the wire it's wound from. So your question
can't be answered unless you tell us the diameter of the coil and any two
of length, pitch, and number of turns; or the length and diameter of the
coil and its inductance at the frequency at which it's being used.

Roy Lewallen, W7EL

John Smith wrote:

My question(s):

For an example, on the 10 meter band:
If I take a 28" whip and mount it at the end of helical wound coil
(wound on
1" diameter form), where the "wire length" of the coil, PLUS, the length
of
the whip (28" + coil wire length) is equal to 1/2 wavelength (electrical
length)--BUT, the overall physical length of the antenna (top, tip of
whip
to base of helical wound coil) is 1/4 wavelength, what would the
radiation
pattern of such an antenna be?

Would it favor the pattern of a 1/4 or 1/2 wave antenna--or, would the
pattern be a compromise between the two--or, would the pattern be
totally
unrelated to either?

What could I expect the impedance of such an antenna be? Would the
reactance be capacitive or inductive? What would be the best way to
provide
a match to 50 ohm coax from such an antenna?

What software is available to model such an antenna?

Thanks in advance,
warmest regards

Absolutely Richard! It does seem difficult with available tools--at least
without building it and even then putting much labor into expermenting,
testing, pruning and adjusting...

Yet, it seems like such a design would suggest itself to many minds and be a
good solution to many restricted spaces and, one does ponder why the math,
methods, formulas, software, etc. has not been created to make such a matter
of childs play--and well documented and explained.

Many mobile whips seem centered around designs somewhat similiar to the one
proposed. And, indeed, I have seen a few expermentally inclined hams
goofing around with similiar designs for shack antennas on the long
wavelengths, just wish I had paid more attention at the time....

I am a capable C/C++ software engineer (professional hacker) and am
constantly searching for ideas to put to code to feed my personal
interests...

Warmest regards

"Richard Clark" wrote in message
news
On Sun, 20 Mar 2005 18:26:42 -0800, "John Smith"
wrote:
what would the radiation pattern of such an antenna be?

Hi John,

This appears to be a difficult question to answer, if for only all of
the extraneous details. Patterns are determined by the physical size
in relation to wavelength. It is all about geometry and distances
between what are called current nodes - what you describe has no s in
the node(s), so the geometry (pattern) is still quite simple.

Obtain a free copy of EZNEC to confirm.

73's
Richard Clark, KB7QHC