Jim Kelley wrote in message ...
Mark Keith wrote:
My argument boils down to: What does this mean to the antenna builder
or modeler?

To the antenna user, or the antenna builder/modeler who doesn't care
about current distribution, it would probably mean nothing.

Well, I care a great deal myself, I can't see how this would help me
at all. What would you do about it?

If any discrepancy is so small to be barely measurable,
all this speculation about gross error when modeling is *to me* a load
of hooey.

The discrepancy varies anywhere from barely measureable to very
measureable.

That says a lot...

Where is the beef that this claimed
variation of current across a coil causes drastic modeling or coil
placement calculation errors? Sorry, I just don't see it. What am I
missing here?

I think it should only matter to people who want to give advice on the
subject.

That doesn't answer the question. MK

Well, I care a great deal myself, I can't see how this would help me
at all. What would you do about it?

Mike,
to put in perspective, and I tried to point out in the course of threading this
thread, the significance is this:

1. Impact on effciency - efficiency is roughly proportional to the area under
the current curve over the radiator. When the current drop across the coil is
significant, that "eats" the portion of the curve and the curve above the coil
is much smaller (cosine or triangle shape), less efficiency (than shown in some
pictures).

2. Understanding the effect allows to better optimize the antenna performance,
be it through modeling or experimenting and measuring. That's why top hats look
so good. We are not talking just fraction of dB, on low bands that shows as 10s
of dBs on signal.

3. Proper modeling in software will allow better design and optimization. See
case of linear loaded 80m KLM beam vs. modified with loading coils, big
difference in pattern and gain and performance.

4. If the modeling software can not capture the effect, than your designs of
multielement loaded antennas are off.

This exercise already opened my eyes wider and after I test the designs, I will
hopefully come up with some better mobile antennas.

Yuri

oSaddam (Yuri Blanarovich) wrote in message

Mike,
to put in perspective, and I tried to point out in the course of threading this
thread, the significance is this:

1. Impact on effciency - efficiency is roughly proportional to the area under
the current curve over the radiator. When the current drop across the coil is
significant, that "eats" the portion of the curve and the curve above the coil
is much smaller (cosine or triangle shape), less efficiency

Sure, it's called varying stinger heights, or varying capacitance. The
less stinger you have, the less current will be pulled through the
coil. Thats the way I see it anyway. If you noticed a taper across a
coil, what would you do about it? How are you going to improve the
antenna, if #1 , the coil is already as high as you can place it, and
#2, the stinger is as long as you can make it.

2. Understanding the effect allows to better optimize the antenna performance,
be it through modeling or experimenting and measuring.

How? I don't see how we can improve over what we are using. We are
already using the optimum coil placement if we want that. Vertload can
tell you that very quickly.

That's why top hats look
so good. We are not talking just fraction of dB, on low bands that shows as 10s of dBs on signal.

Huh? Top hats work well, because of a current taper across the coil?
Top hats don't model properly because of a current taper across a
coil? I'm confused...


3. Proper modeling in software will allow better design and optimization. See
case of linear loaded 80m KLM beam vs. modified with loading coils, big
difference in pattern and gain and performance.

Where would I see this? Normally, I would expect the lumped coil
version to be the most efficient if quality coils are used...

4. If the modeling software can not capture the effect, than your designs of
multielement loaded antennas are off.

Thats a big if though...I've already shown that the likely error from
this "taper" would most likely be so small to be unnoticed. So far, no
one has shown it to be otherwise.


This exercise already opened my eyes wider and after I test the designs, I will
hopefully come up with some better mobile antennas.

Yuri

Thats the bottom line. But I still feel I'm already building mine as
well as they can be. MK

Mark Keith wrote:
"But I still feel I`m already building mine as well as they can be."

Close the patent office!

Best regards, Richard Harrison, KB5WZI

Mark Keith wrote:
"But I still feel I`m already building mine as well as they can be."

Close the patent office!

Best regards, Richard Harrison, KB5WZI




Bingo!

In order not to rush Phreak into the patent office I will sit on some solutions
for a while. :-)

3BUmmer

Hi All,

After having asked more than once for simple characteristics, taken
Tom's speculative offering of 300µH (to which Yuri neither accepted
nor rejected, nor offered amendment to, nor any value of his own, nor
attempted to confirm or reject through his correspondence); I settled
down to hammering through the values to make it ring using the other
speculations of simple characteristics that remain wholly undisclosed
(see enumeration above).

The valuation offered by Tom was easily 1000% high. That I suggested
that my model did not resonate came to no response by Yuri, who was
quick to accept testimony of there being a current differential (which
was also in reverse characteristic to those so-called measurements).

Instead, I used what metrics were offered in the casual report and by
evidence of photography to mock up the following:
0.375" Diameter copper (with losses) radiator length at 92";
a ground field of 60 #12 copper (with losses) radials;
a 36.8267µH lumped coil (no losses attributed through R, no C);
the lumped coil placed at the 46th inch (49.45%);
the antenna placed over real ground;
ground is of medium characteristic;
the entire antenna/ground plane is 6" above actual ground;
that comes to the following current distribution:
1 W2E1 1 0.00
2 1.0005 0.00
3 1.0012 -0.01
4 1.0019 -0.02
5 1.0027 -0.03
6 1.0035 -0.03
7 1.0043 -0.04
8 1.0051 -0.05
9 1.006 -0.05
10 1.0069 -0.06
11 1.0079 -0.06
12 1.0089 -0.07
13 1.0099 -0.07
14 1.011 -0.08
15 1.0121 -0.08
16 1.0132 -0.09
17 1.0144 -0.09
18 1.0156 -0.10
19 1.0169 -0.10
20 1.0182 -0.10
21 1.0195 -0.11
22 1.021 -0.11
23 1.0224 -0.12
24 1.024 -0.12
25 1.0256 -0.12
26 1.0273 -0.13
27 1.029 -0.13
28 1.0309 -0.13
29 1.0328 -0.14
30 1.0349 -0.14
31 1.0371 -0.14
32 1.0394 -0.14
33 1.0418 -0.15
34 1.0445 -0.15
35 1.0473 -0.15
36 1.0503 -0.16
37 1.0535 -0.16
38 1.0571 -0.16
39 1.061 -0.16
40 1.0653 -0.16
41 1.0702 -0.17
42 1.0759 -0.17
43 1.0826 -0.17
44 1.091 -0.17
45 1.1039 -0.17
46 1.1224 -0.18
47 1.0841 -0.18
48 1.0513 -0.18
49 1.0231 -0.18
50 .99652 -0.18
51 .97101 -0.18
52 .94623 -0.18
53 .92201 -0.19
54 .8982 -0.19
55 .87475 -0.19
56 .85159 -0.19
57 .82863 -0.19
58 .80587 -0.19
59 .78328 -0.20
60 .76083 -0.20
61 .73849 -0.20
62 .71627 -0.20
63 .69412 -0.20
64 .67205 -0.20
65 .65004 -0.20
66 .62807 -0.21
67 .60614 -0.21
68 .58425 -0.21
69 .56237 -0.21
70 .5405 -0.21
71 .51863 -0.21
72 .49675 -0.21
73 .47485 -0.22
74 .45294 -0.22
75 .43099 -0.22
76 .40898 -0.22
77 .38692 -0.22
78 .3648 -0.22
79 .34259 -0.23
80 .32028 -0.23
81 .29787 -0.23
82 .27531 -0.23
83 .25259 -0.23
84 .22969 -0.23
85 .20656 -0.23
86 .18316 -0.23
87 .15942 -0.24
88 .13523 -0.24
89 .11047 -0.24
90 .08486 -0.24
91 .05798 -0.24
92 Open .02713 -0.24

for each INCH of the radiator (and lumped coil)
A visual description would be a constant current to the coil, and then
a linear taper to the tip.

The corresponding launch characteristic:
1.80dBi @ 29°

By Decimating the lumped value across 10" (corresponding to the large
solenoid's apparent size ascertained from the photographs); to 10
lumped values of 4.28078µH (adjusted to re-obtain resonance); placed
at successive 1 inch segments (50..59); we find the following changes:
1 W2E1 1 0.00
2 1.0005 0.00
3 1.0011 -0.02
4 1.0017 -0.02
5 1.0024 -0.03
6 1.0031 -0.04
7 1.0039 -0.04
8 1.0047 -0.05
9 1.0054 -0.05
10 1.0063 -0.06
11 1.0071 -0.07
12 1.008 -0.07
13 1.0089 -0.08
14 1.0099 -0.08
15 1.0108 -0.09
16 1.0118 -0.09
17 1.0129 -0.10
18 1.014 -0.10
19 1.0151 -0.11
20 1.0162 -0.11
21 1.0174 -0.11
22 1.0187 -0.12
23 1.02 -0.12
24 1.0213 -0.13
25 1.0227 -0.13
26 1.0241 -0.13
27 1.0256 -0.14
28 1.0272 -0.14
29 1.0289 -0.14
30 1.0306 -0.15
31 1.0324 -0.15
32 1.0344 -0.15
33 1.0364 -0.16
34 1.0385 -0.16
35 1.0408 -0.16
36 1.0432 -0.17
37 1.0458 -0.17
38 1.0485 -0.17
39 1.0515 -0.17
40 1.0547 -0.18
41 1.0582 -0.18
42 1.0621 -0.18
43 1.0665 -0.18
44 1.0714 -0.18
45 1.0776 -0.19
46 1.0854 -0.19
47 1.0886 -0.19
48 1.0876 -0.19
49 1.083 -0.19
50 1.0748 -0.19
51 1.0633 -0.20
52 1.0484 -0.20
53 1.0301 -0.20
54 1.0084 -0.20
55 .98291 -0.20
56 .9533 -0.20
57 .92528 -0.20
58 .8983 -0.21
59 .87192 -0.21
60 .84597 -0.21
61 .82036 -0.21
62 .79502 -0.21
63 .7699 -0.21
64 .74494 -0.21
65 .72014 -0.22
66 .69545 -0.22
67 .67086 -0.22
68 .64635 -0.22
69 .62191 -0.22
70 .59751 -0.22
71 .57314 -0.22
72 .5488 -0.23
73 .52446 -0.23
74 .50012 -0.23
75 .47576 -0.23
76 .45136 -0.23
77 .42692 -0.23
78 .40243 -0.23
79 .37785 -0.24
80 .35318 -0.24
81 .32841 -0.24
82 .30348 -0.24
83 .2784 -0.24
84 .25312 -0.24
85 .22759 -0.24
86 .20178 -0.24
87 .1756 -0.25
88 .14894 -0.25
89 .12165 -0.25
90 .09344 -0.25
91 .06384 -0.25
92 Open .02987 -0.25

for each INCH of the radiator (and lumped coil)
A visual description would be a constant current to the coil, and then
a linear taper to the tip. It should be noted that for the protocol
of solenoid assembly by lumped parts, the current into the solenoid
does not equal the current out of the solenoid.

The corresponding launch characteristic:
1.56dBi @ 29°

Or roughly a quarter dB difference between the two (being generous, a
6% variation in absolute signal strength)

Any surprises? Perhaps to the easily surprised, but a quarter dB
variation hardly counts in the real world. Moment to moment
propagation variation will eclipse or boost this easily (although
employing 0.3dB to boost or eclipse is a strain on language). The
real world is going to suffer the bitch of matching R (being resonant
does not confer a 50 Ohm match to this small radiator). Does the
current drop through the solenoid? Again, no surprise. Does it drop
enough? Well that is arguable given the lack of attention to details
of specifying the original test.

Has any new precept been obtained that has not already been supplied?
Insofar as the complaint of not seeing the current variation goes,
that was answered long before the 350 itinerant postings that ignored
it. Does the decimation offer enough accuracy? Angel population
counts will undoubtedly be re-entered into with relish to make that
illusionary exploration despite the obvious variation of so little as
a quarter dB did for the first huge leap being the greatest difference
that will be found.

73's
Richard Clark, KB7QHC

"Richard Clark" wrote -

The valuation offered by Tom was easily 1000% high.

.................................................. ............

Sounds a lot. Do you mean it was 10 or was it 11 times bigger?

(Richard Harrison) wrote in message ...
Mark Keith wrote:
"But I still feel I`m already building mine as well as they can be."

Close the patent office!

Best regards, Richard Harrison, KB5WZI

Nothing to patent. I didn't invent them. I think I see now why Roy
bailed out.
It's starting to get silly.
We are talking about something that is already very well known. Or at
least when applied to mobile antennas. There is nothing new about
optimizing the coil location to improve current distribution. The
various heights above the base have been hashed out and tested
ad-nausium till the cows come home. There is nothing new about using
a top hat to improve current distribution. Ditto on the
testing...There is nothing new about ground losses usually
overshadowing coil losses with most mobile setups. Yuri tells me to go
back to my rubber room, but read his previous post first,and I did.
But I see nothing there that is new as far as pertaining to mobile
antenna design. Not a single thing. Now if it's proven that errors
could been seen when modeling arrays, or whatever, I can see that as
useful. Not that I'm convinced it's a major problem yet mind you...But
I could see finding usable modeling improvement with complex arrays
much more likely than the lowly whip and coil.
When it comes to mobile antennas, I think they have pretty much
reached the state of the art as far as the design of a coil loaded
short antenna goes. All variations of loading positions have already
been tested virtually non stop since at the very least the 50's, when
bugcatchers became very common. I've got a 1935 QST with a mobile on
the front, but he's not using a bugcatcher. Crap, what more can you
do with a simple whip and coil....:/ They have been beat to death
looking for the very last drop for 50 solid years. I've personally
beat them to death myself looking for the last drop since at least
1988-89 or so when I got my first mobile radio. Trust me, I can't
really improve over what I have now without getting ridiculous or
undrivable or too heavy. I'm already over the legal 13.6 ft height
limit as it is. My coil is already elevated from the base 50% when
driving, "10 ft antenna, with the base 4.5 ft off the ground" 62% up
when parked with the lower mast. "13 ft antenna" With the 13 ft
version, my coil is higher than some peoples whole antenna. Appx 12.5
ft off the ground.
I can't physically install the coil any higher than that due to the
fiberglass mast I use for the lower main section. I installed the coil
at the very top, and use a 5ft thin stinger whip above the coil. It
wouldn't help a whole lot more anyway. It's better to keep the same
longer stinger length and add mast below the coil. Heck, I agree with
almost everthing he promotes as far as mobile antenna design as far as
coil placement, hats, etc. But it's sure nothing new or earthshaking.
I've seen nothing so far to indicate we are designing in gross error
or even noticable error. I've seen nothing to indicate that any new
data gleaned from his tests will improve mobile antenna design enough
to notice in FS measurements. He suggests nothing new that already
isn't being utilized. Where's the all important beef?
I'm not trying to be difficult, I'm just asking the fairly obvious. I
ask very simple questions and what do I get? Bafflegab deflection
tactics, rehashes of past social dilemmas, or just vague, totally
useless comments from one. I think I'm gonna bail on this thread also.
I have better things to do than chase my tail and bark at the moon. My
position on the current state of mobile antenna design is fairly well
known at this point. I'll just leave it at that. MK

Mark Keith wrote:
"I`ve seen nothing so far to indicate we are designing in gross error or
even noticible error."

Neither have I. But, I`ve read several stimulating perceptions which
were new to me and motivated me to investigate and improve my
understanding.

I am sorry My statement, "Close the patent office!" offended Mark. I
have no doubt that Mark has optimized his mobil antennas.

Forty years after Faraday suggested the existence of electric fields in
about 1842,
Heinrich Hertz built a spark transmitter and receiver. The receiver was
just a loop with a gap which sparked when Hertz keyed his transmitter.
It was resonant at 53 MHz or near the frequencies now assigned as TV
Channel 2 in the USA. Hertz optimized his antennas for maximum
transmission distance and achieved about 30 feet.

In the last 160 years there have been many interesting antenna
developments and more are yet to come. Most are not likely predictable.

Best regards, Richard Harrison, KB5WZI

(Mark Keith) wrote in message om...
(Richard Harrison) wrote in message ...
Mark Keith wrote:
"But I still feel I`m already building mine as well as they can be."

Close the patent office!

Best regards, Richard Harrison, KB5WZI

Nothing to patent. I didn't invent them. I think I see now why Roy
bailed out.
It's starting to get silly.
We are talking about something that is already very well known. Or at
least when applied to mobile antennas. There is nothing new about
optimizing the coil location to improve current distribution. The
various heights above the base have been hashed out and tested
ad-nausium till the cows come home. There is nothing new about using
a top hat to improve current distribution. Ditto on the
testing...There is nothing new about ground losses usually
overshadowing coil losses with most mobile setups. Yuri tells me to go
back to my rubber room, but read his previous post first,and I did.
But I see nothing there that is new as far as pertaining to mobile
antenna design. Not a single thing. Now if it's proven that errors
could been seen when modeling arrays, or whatever, I can see that as
useful. Not that I'm convinced it's a major problem yet mind you...But
I could see finding usable modeling improvement with complex arrays
much more likely than the lowly whip and coil.
When it comes to mobile antennas, I think they have pretty much
reached the state of the art as far as the design of a coil loaded
short antenna goes.

Can you tell me where I can find what the orientation of coil cross
section does for efficiency ?
There are circular cross sections, edge wound cross sections and also
the ribbon type that Collins uses where the ribbon is coiled on a
adjacent coil former, why did they choose this method?
I am pursuing efficiency, reduction of losses and Collins have a great
reputation so which form is the state of the art especially with
corner flux density.
Another question is that if we split up an inductance into two parts
does the form factor include the summation of inductances or does the
distance inbetween
where coil linkage is not fully formed affect efficiency for the
worse.
Discussion like this thread hopefully will enlarge our education to
see if such things matter . Another question I struggle with is to put
another element inside the coil where there is max flux density but
again it can't be resolved by modeling. With the multi antenna experts
onboard it is always a possibility that a modicom of information will
be provided that will benefit all.
As far as inductances, all is not known to my mind and I always would
like to be privy to more information, and not because I want to build
a whip






All variations of loading positions have already
been tested virtually non stop since at the very least the 50's, when
bugcatchers became very common. I've got a 1935 QST with a mobile on
snipThey have been beat to death
looking for the very last drop for 50 solid years. I've personally
beat them to death myself looking for the last drop since at least
snip Where's the all important beef?
I'm not trying to be difficult, I'm just asking the fairly obvious. I
ask very simple questions and what do I get? Bafflegab deflection
tactics, rehashes of past social dilemmas, or just vague, totally
useless comments from one. I think I'm gonna bail on this thread also.
I have better things to do than chase my tail and bark at the moon. My
position on the current state of mobile antenna design is fairly well
known at this point. I'll just leave it at that. MK

Regards
Art