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
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