Absolutely, and, "If it works don't complain!", is my motto.
Still, my mind ponders and responds with questions...



One thing I haven't been forth coming with is the 1/4 wave antenna. Really,
I don't know what specs a "proper" one should be constructed to (working off
very basic ARRL diagram).

The one I built has a very heavy stainless whip--most likely is military
surplus, but years ago I bought a whole slew of them and still have not used
them up, the whip base is about 3/8 and tapers at approx. 12 feet to a 3/16
dia.

I just hacked it to a 1/4 wave with the 1/4 ant length formula provided by
the ARRL book and removed length with a very course file, until resonate.
The radials are 1/2" aluminum rod and heavy. The insulating material for
the whip is cut from 1-1/4" thick nylon sheet. The SWR was originally high,
but "drooping" (ARRL book suggested this) the ends of the radials, down near
a 45 degree angle, provides 1:1.5. The radials are cut 5% wave longer than
the whip (again, suggested by ARRL book), they are grounded to the mast and
the mast has a good earth ground. Antenna is directly fed with 50 ohm coax.

Perhaps my construction of the 1/4 is less than optimum? And, this may make
it appear that the antenna from my original post is performing better than
it really is.... thoughtful frown

The weather here is high wind and rain. I will not be tempted to do any
more experimenting until this passes...



Regards



Hey! If you can't provide and suggestions, how about just spell checking
this for me?



"Roy Lewallen" wrote in message
...
If there's no ground system loss, a half wave vertical antenna has about
1.3 dB gain over a quarter wave vertical due to the sharper pattern shape.
This is the line-of-sight or surface wave gain difference. If reflection
from real ground is included in the analysis, the gain difference is about
1 - 1.5 dB at lower angles, and the quarter wave does much better, by 3 or
4 dB or so, at high angles (very roughly above 50 degrees or so).

Coil loading to achieve half wave resonance does have one potential
advantage, and that's to reduce ground loss when substantial ground
resistance is present. Because of the much higher base impedance, ground
current is much less with a half wave resonant base fed antenna than with
a quarter wave antenna, even when the resonance is achieved with coil
loading. Ground loss is typically pretty low on ten meters in mobile
applications, but in some other setups (such as ground mounting over a
buried radial system, or a hand-held radio), the reduction in ground
current could reduce ground loss more than enough to compensate for coil
loss.

I suspect this is the explanation for at least some of any advantage you
see in the coil loaded antenna over a straight wire of the same length.
However, there's a good sized handful of other possible factors. (Every
last one of them, incidentally, explainable perfectly well by "standard
theory".) If the measurement results don't agree with the model, it nearly
always means that the actual antenna -- that is, the "antenna", the
"ground" system, and everything connected to either one or in the near
field of either one -- differs from the model in some significant way. Or
the measurement system is faulty.

Someone interested in understanding the operation of an antenna will
commonly spend a great deal of time tracking down the factors that differ
between the model and real antenna, and it's just about always a truly
educational experience. When done, the result is usually a model that
really represents the antenna system, and that shows results very close to
careful and competent measurements. And an experimenter who knows more
about antennas, modeling, and the importance of some factors he never
before considered. You go through this exercise a few hundred times, like
professional engineers routinely do, and you come out with a great respect
for "standard theory" and an even greater level of skepticism toward
people who have a weak understanding of it and are convinced they've
witnessed a miracle. Those of us who have spent a career using "standard
theory" to design real, useful items that work as designed haven't become
skeptical because our brains have been petrified by education; it's
because we've seen "standard theory" work, over and over and over, and
every last miracle inevitably fall, one after another, to careful scrutiny
and understanding.

But we also eventually come to realize that astrology, homeopathy, and
feng shui(*) will be with us forever. People will simply believe what
suits them, and won't be bothered by evidence. Especially if the evidence
takes effort, knowledge, patience, and understanding to acquire.

The "S-Unit" is a nice homey amateur unit of measurement, but it has no
meaning. (Some people seem to think it's equal to 6 dB, but vast numbers
of others think it's the the size of the markings on their receivers' "S
Meter". The two can be very different.) dB, on the other hand, is a
universally defined and understood unit. Anyone unable to accurately
measure relative values in dB is unable to make quantitative gain
measurements at all.

(*) My spell checker didn't recognize this, so I did a quick google search
to see if I got it right. It came up with 2,180,000 hits. There's no lack
of believers.

Roy Lewallen, W7EL

John Smith wrote:
Well, I have 3 test antennas on this project:
1) 1/4 wave stainless steel whip w/4 heavy 1/2 inch, aluminum ground
plane radials
2) 1/2 wave without any ground plane/counterpoise, lower 1/4 wave section
is 3/4 copper pipe, upper 1/4 is a stainless whip, total of the
combination is 1/2 wave... ferrite beads are used on the outer shield of
the coax at the point where it connects to the antenna, match is though a
simple l-network (ferrite beads are actually un-needed but used anyway,
no real detectable radiation from coax either way)
3) This is the antenna I described in the first post(s), I tend to refer
to as the "quarter/half", it is constructed on 3/4 ID pvc pipe, and has
an OD of just over an inch, the coil is constructed of #8 copper wire and
the top whip is the 28 inch stainless whip I mentioned. Is a resonate
1/2 wave and physical 1/4 (whip + helical coil length.) Matching network
is a l-network, capactior is constructed of acrylic insulator plates
(acrylic "window pane") with copper sheet plates, coil is a 1.3 OD
torroid. coil is approx. 1+ uh (computed from toroid data)--I have not
measured the capacitance of the capacitor (probably somewhere from 20+ pf
to 30+ pf), no groundplane/counterpoise, ferrite beads as above.

Naturally, as the models predict, the 1/4 is lower in preformance than
the half 1/2, and very noticable in the most distant contacts.
However, the "quarter/half" out preforms the 1/4 but falls lower in
preformance than the 1/2. Contacts out at 30+ miles are where the
electrical 1/2 wave antennas differ most from each other (antennas 2 and
3 above.)
FSM measurements of the two 1/2 waves are very simuliar--however, these
measurements could have been taken at a greater distance to increase
accuracy (meters sensitivity I currently am using limited this.)
Franky, I was surprised by the preformance. As others have predicted--I
expected the preformance of the shortened 1/2 wave to be poorer than the
1/4 (mainly due to the helical coil skewing the radiation pattern and
adding a slight resistance to a physical 1/4 antenna.)
However, it seems to fall in the middle between the 1/4 and the 1/2 wave
(full length) antennas, favoring being closer to the 1/2 full length by
1/2 S-unit+
The biggest difference between the 1/4 and 1/2 wave full length is 2-3
s-units at stations in the 30+ mile distances.
The full 1/2 wave and the shortened 1/2 wave seem close to 1 s-unit on
all apparent distant stations.
I find this hard to believe, and the models I calculated did not reflect
what I had actually seen in s-units.

All three antennas were placed at the same height, on the same mast while
testing (32 ft above real ground.) And all other conditions the same.
The l-network match is the only difference between the two 1/2 wave
antennas, in the future I will correct this and finalize the tests... the
difference in the matches could be responsible for the difference in
expected results.
Right now, it actually looks to me, from the above--that the "1/4
physical, 1/2 wave electrical (quarter/half)" antenna was and is
exhibiting properties of both a 1/4 and a 1/2 wave antenna. This is the
main reason I tossed out this "antenna problem" here, to see others
reactions and draw from their experience.

Warmest regards

"Buck" wrote in message
...

On Sun, 20 Mar 2005 18:26:42 -0800, "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



EZNec will model your antenna. As for the antenna, I believe that the
shortened 1/2 wave antenna will radiate with less effect than a
stretched 1/2 wave, but possibly better than a 1/4 wave. How much?
That depends on the coil and the matching network pending losses.

Good luck,
Buck
N4PGW

--
73 for now
Buck
N4PGW

You said you made your antenna with a base loaded coil and added an
L-matching network. I have been reading the ARRL manual which says
that the center loaded coil produces a different current curve and a
better match.

Assuming that the L-network produces some (any) loss, the better match
will theoretically overcome that. However, the inductor has to be
considerably larger and inductors are somewhat lossy.

Has anyone tried, and/or can anyone model this version to see how it
compares?


--
73 for now
Buck
N4PGW

Buck,

I disagree with you on this. If the coil does indeed resonate the
antenna in 1/2 wave, antiresonance, current distribution will be
different than the straight quarterwave resonance. The current maximum
will occur in roughly the center of the loacing coil length with a
current minimum at the bottom. Since photon generation is an
ampere/length concern, there must be a greater peak coil current to
achieve the same power radiated. That would probably incur greater
losses than quarter wave resonance.

The half wave resonance might have an advantage if there is a problem
achieving an adequate counterpoise under the antenna for normal quarter
wave resonance. A lot of through-the-glass mobile antennas have been
sold using this principle.

I wonder if Roy has a simple way to include the coil Q or losses in the
EZNEC model. I'm sure there is a logical way to work it out but I
haven't had time to think it through yet.

Gary - N0GW

N0GW wrote:
. . .
I wonder if Roy has a simple way to include the coil Q or losses in the
EZNEC model. I'm sure there is a logical way to work it out but I
haven't had time to think it through yet.

Sure. If modeling it as a helix, simply specify wire loss for the type
of wire or plating on the wire used for the coil. (The loss in the coil
will be much greater than the loss in the straight wire, so it's no big
deal if the straight wire is made from some other material.) If modeling
it as lumped loads (not as accurate), include the appropriate value of R
in the loads. You can quickly and easily see how much loss the coil is
causing by comparing gain with the loss present and absent.

A few experiments showed a pretty close agreement between EZNEC's helix
model with wire loss and Reg's inductor program with regard to L,
resonant frequency, and Q. I didn't, however, run tests with a wide
range of coil geometries and wire sizes.

The EZNEC helix model will underreport loss if wire spacing is less than
one or two wire diameters, since it doesn't account for proximity effect
(uneven current density around the wire).

Although you can manually (and tediously) build a helix model with EZNEC
v. 3.0 or EZNEC-ARRL which is v. 3.0, or create one with an external
program and import it, EZNEC v. 4.0 has a built-in helix creation
feature that generates a helical coil with a few keystrokes.

Roy Lewallen, W7EL

Buck wrote:
On Sun, 20 Mar 2005 18:26:42 -0800, "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



EZNec will model your antenna. As for the antenna, I believe that
the
shortened 1/2 wave antenna will radiate with less effect than a
stretched 1/2 wave, but possibly better than a 1/4 wave. How much?
That depends on the coil and the matching network pending losses.

Good luck,
Buck
N4PGW

--
73 for now
Buck
N4PGW

Well....
I could have stated a less controversial design I guess.
Such as an antiresonate antenna cap--folded from aluminum foil, and intended
to cancel out the moon bounced mind control rays from the aliens.
Since totally shielding the walls of my home with silver foil has failed to
block the penetration of these "antenna rays" into my home, the cap might be
just the ticket!
The burning question here would be what wavelength of foil the cap should it
be folded from, and heck, I don't even think the frequency of their mind
control rays registers on earth meters!
It is a conspiracy, I TELL YA!!! grin

Regards
"John Smith" wrote in message
...
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

Actually, and back to reality:
I am in the San Joaquin Valley in California, while this used to be one of
the richest agricultural areas in the world, decades of double and triple
farming has depleated the soil of many of the plentiful nutrients (salts,
trace minerals, metals, etc.)
Also, this area was like a tule swap before levies were built to hold back
the water, i.e., a peat bog!
Those who mentioned a poor and lossy ground condition might have something
there...
This area may naturally favor the 1/2 properties.

But then too, maybe it is only those damn aliens with their mind control
which are placing these ideas in my head! grin Yanno, agriculture uses a
lot of those darn illegal aliens' labor!!!

Regards

"John Smith" wrote in message
...
Well....
I could have stated a less controversial design I guess.
Such as an antiresonate antenna cap--folded from aluminum foil, and
intended
to cancel out the moon bounced mind control rays from the aliens.
Since totally shielding the walls of my home with silver foil has failed
to
block the penetration of these "antenna rays" into my home, the cap might
be
just the ticket!
The burning question here would be what wavelength of foil the cap should
it
be folded from, and heck, I don't even think the frequency of their mind
control rays registers on earth meters!
It is a conspiracy, I TELL YA!!! grin

Regards
"John Smith" wrote in message
...
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, the "1/4 physical, 1/2 electrical" (double quarter as my friend refers
to it) will just have remain as it is.
Its' advantage of being lighter and easier to handle, while presenting less
of a wind load and "leverage" again the mast and mounting hardware allows me
to raise it to a greater height than the full 1/2--NOT to mention the
advantage of NO ground radials. With this advantage, its performance rivals
the full 1/2. Weather I am daft or not--I will be using this antenna for an
omnidirectional source.
Those seeking a backpacking antenna, an emergency portable antenna, or an
antenna for operation in difficult and remote areas, or those seeking
stealth (just hide it in a larger diameter PVC pipe and call it a flag
pole!) would, most likely, find this design can be used to their advantage.

This posting sequence has been an enlightening experience though, and well
worth the trouble. I have learned that most will wage a "religious war" if
they think anyone is going to challenge the generally accepted ideas and
methods.
If you insist on going on, you will run the gauntlet of nay sayers and be
attacked. Guffaws and slurs against your mental stability will assualt you.
If one is looking to try something new--this is NOT the place to discuss it.
Perhaps another news group, where those who seek to intimidate and "out
shout" true expermenters would be banned and refused posting would be a
workable alternative and more conductive to attempts to break the mold.

Regards

"John Smith" wrote in message
...
Actually, and back to reality:
I am in the San Joaquin Valley in California, while this used to be one of
the richest agricultural areas in the world, decades of double and triple
farming has depleated the soil of many of the plentiful nutrients (salts,
trace minerals, metals, etc.)
Also, this area was like a tule swap before levies were built to hold back
the water, i.e., a peat bog!
Those who mentioned a poor and lossy ground condition might have something
there...
This area may naturally favor the 1/2 properties.

But then too, maybe it is only those damn aliens with their mind control
which are placing these ideas in my head! grin Yanno, agriculture uses
a
lot of those darn illegal aliens' labor!!!

Regards

"John Smith" wrote in message
...
Well....
I could have stated a less controversial design I guess.
Such as an antiresonate antenna cap--folded from aluminum foil, and
intended
to cancel out the moon bounced mind control rays from the aliens.
Since totally shielding the walls of my home with silver foil has failed
to
block the penetration of these "antenna rays" into my home, the cap might
be
just the ticket!
The burning question here would be what wavelength of foil the cap should
it
be folded from, and heck, I don't even think the frequency of their mind
control rays registers on earth meters!
It is a conspiracy, I TELL YA!!! grin

Regards
"John Smith" wrote in message
...
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

This posting sequence has been an enlightening experience though, and
well
worth the trouble. I have learned that most will wage a "religious
war" if
they think anyone is going to challenge the generally accepted ideas
and
methods.
If you insist on going on, you will run the gauntlet of nay sayers and
be
attacked. Guffaws and slurs against your mental stability will
assualt you.
If one is looking to try something new--this is NOT the place to
discuss it.
Perhaps another news group, where those who seek to intimidate and
"out
shout" true expermenters would be banned and refused posting would be
a
workable alternative and more conductive to attempts to break the
mold.
.................................................. .....................
I think I'm going to vomit....Are you related to Art? If not,
you should be....Whine, whine, whine.... You think you are the
first one to try that? I tried that using my helical mobile
antennas years ago...Big deal...BTW...I ended up preferring the
normal 1/4 wave config for a mobile antenna...Just in case thou
art interested...I also agree with one poster...The biggest change
will be with the current distribution...
They were making CB antenna *years* ago, using that "extended winding"
type of design...Many were a 5/8's wl winding. Sheesh....Get a grip.
Quit whining...Religious war? Slurs against your stability? Will be
soon, if you don't quit this retched "poor ole maligned me" whining.
You never saw me say anything about the antenna itself. Why? Cuz
being I have tried it, I know they can work. But like I said,
I ended up not using it as the normal 1/4 wl config worked better
on my car. Trust me...The idea has been tried long ago.
There is nothing wrong with posting something new here. Although
to others, it might not be new at all.
In fact, if you are *actually* interested in if it's viable,
this is probably the best place. You won't get suger coated
bullcrap here...
Now, if you are trying to push some funky device like say the EH
antenna, yep, you probably don't wanna be here...Go to a yahoo
forum where all have to register to join. That way you can control
all the posts, and make the outcome of your "discovery" come out
any way you want. Sheesh...
MK

Oh yeah, I forgot to make mention of the "nuts"...

Regards

wrote in message
oups.com...
This posting sequence has been an enlightening experience though, and
well
worth the trouble. I have learned that most will wage a "religious
war" if
they think anyone is going to challenge the generally accepted ideas
and
methods.
If you insist on going on, you will run the gauntlet of nay sayers and
be
attacked. Guffaws and slurs against your mental stability will
assualt you.
If one is looking to try something new--this is NOT the place to
discuss it.
Perhaps another news group, where those who seek to intimidate and
"out
shout" true expermenters would be banned and refused posting would be
a
workable alternative and more conductive to attempts to break the
mold.
.................................................. ....................
I think I'm going to vomit....Are you related to Art? If not,
you should be....Whine, whine, whine.... You think you are the
first one to try that? I tried that using my helical mobile
antennas years ago...Big deal...BTW...I ended up preferring the
normal 1/4 wave config for a mobile antenna...Just in case thou
art interested...I also agree with one poster...The biggest change
will be with the current distribution...
They were making CB antenna *years* ago, using that "extended winding"
type of design...Many were a 5/8's wl winding. Sheesh....Get a grip.
Quit whining...Religious war? Slurs against your stability? Will be
soon, if you don't quit this retched "poor ole maligned me" whining.
You never saw me say anything about the antenna itself. Why? Cuz
being I have tried it, I know they can work. But like I said,
I ended up not using it as the normal 1/4 wl config worked better
on my car. Trust me...The idea has been tried long ago.
There is nothing wrong with posting something new here. Although
to others, it might not be new at all.
In fact, if you are *actually* interested in if it's viable,
this is probably the best place. You won't get suger coated
bullcrap here...
Now, if you are trying to push some funky device like say the EH
antenna, yep, you probably don't wanna be here...Go to a yahoo
forum where all have to register to join. That way you can control
all the posts, and make the outcome of your "discovery" come out
any way you want. Sheesh...
MK