Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

Hi All,

This is a variation on themes being played out. As the title
suggests, you too can force your modeler to give you phenomenal
results in just 5 minutes! Think of it, 20 dBi from a short Dipole -
but first the story:

While I was pondering the coil current flow tricks, I mused over the
thought of instead loading a short antenna with the inverse of
inductance, capacitance. Instead of using suspect lumped loads, I
instead chose to load the wire with insulation. And not just any
insulation.

Insulation found on typical wire comes in a vary small range of
values. They exhibit dielectric constants from 2 to 4, and rarely
that high. If I were to take a load of it, say in the form factor of
a Texas Bugcatcher coil - what would happen?

Not much it seems. However, I am not one to let that slow me down and
I considered a list of elements and materials to examine them for the
highest DCs available. I was thinking of waxes primarily. The
thought ran that I would turn a small HF antenna into a candle and see
if that would slow the Vf.

Waxes do offer higher DCs, but not markedly so. I started to think
salts next, considering that the common round salt box was about the
same size as a large coil. Salts have a high DC (up to the teens),
but even there, not much effect.

Then I turned to what is commonly available, and exhibits a very high
DC - water (dielectric constant of 80). I started with a meter high
tube of 4 inches diameter (been thinking a lot about plumbing this
week when contractors built a French drain in the basement) and
plunked a short (5M) vertical antenna into it.

THIS made a difference. (OK, so did others, but not like THIS).

What the hell, I started to make the diameter bigger to see where the
limits of failure were. Turned out to be around 12 inches thick water
jacket. This was for a monopole in a truck bed I though (fair amount
of weight and sloshing in this linear load). However, it had the
intended consequence of providing 5.6dBi gain.

Now, this gain has to be taken in the perspective of the unjacketed
radiator that exhibits -4.85dBi gain. More than 10dB gain by adding
this water jacket! Hosanna! Of course, if I trimmed this thickness
to goose up the gain, THEN the modeler failed with reports of negative
resistance (due to possible problems that could not possibly exist).

Well, time to reduce complexity and do the same thing with a short
dipole in space (10M long excited at 3.8MHz). This antenna is
constructed with 10 wires so that only the first wires closest to the
feed are insulated. I increased the size of the water jacket and
noted results for drive point impedance, average gain, and best gain.
The binomial progression is edited from a longer list. The results
are as follows:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
0 4.1 - J 1646 -0.02 1.77
10 3.726 - J 1437 0.039 2.17
20 3.498 - J 1305 0.66 2.45
40 3.2 - J 1133 1.05 2.83
80 2.848 - J 930 1.55 3.34
160 2.46 - J 705.8 2.19 3.98
320 2.051 - J 469.5 2.98 4.77
600 1.67 - J 249.5 3.87 5.66
1211.67 1.238 - J 0.0013 5.17 6.96
2200 0.8685 + J 213.2 6.71 8.5
4000 0.4971 + J 427.7 9.13 10.92
8000 0.0656 + J 676.9 17.93 19.71

As you can see, a water jacket 16 meters wide around the first
meter(s) of the dipole offer considerable gain and nothing suggesting
that further enlargement was going to upset this trend. I wasn't
going to push it anyway because it looked exceedingly suspicious.

As suspicious as it may appear, it shows a rather smooth progression.
It was pleasing to note how the load reactance shifted from capacitive
to inductive. I posted a note to Roy who confirmed the intent for the
insulation entry was to limit it to common coating dimensions.
However, there is nothing in the data to suggest a logic breakdown in
my progressions.

On the other hand, when I pushed this further by reducing the wire
size (10 wires per element instead of 5, while keeping the same total
length), I noticed the effect was more remarkable:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
1000 0.2847 + J 139.9 10.98 12.76

A 1 meter water jacket on a shorter wire induced more gain than the
former 4 meter water jacket from the series of results above.

To me, this suggested a boundary violation more so than a thickness
failure mechanism. There are cautions or prohibitions in connecting
different size wires, it seems that extends to insulations' diameter
mismates even when the wires' diameters (25.4mm) are identical
throughout.

So, the object lesson seems to be
Do not try this at home,
or
in the back yard;
or
Do not fill your truck bed with water flooding your HF antenna

73's
Richard Clark, KB7QHC

p.s.
Just in case there is nothing wrong with the model, I hereby cede this
to the public domain and this is notice of prior art.

Insulation diameter vs Impedance OR how to get 20dBi out of ashort Dipole
 

Richard Clark wrote:
Just in case there is nothing wrong with the model, I hereby cede this
to the public domain and this is notice of prior art.

Years ago, I came up with an EZNEC model that has 24 dBi
omnidirectional gain. It can be downloaded from:

http://www.qsl.net/w5dxp/SUPRGAIN.EZ
--
73, Cecil http://www.qsl.net/w5dxp

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

On Sun, 30 Apr 2006 11:23:18 -0700, Richard Clark
wrote:

Hi All,

This is a variation on themes being played out. As the title
suggests, you too can force your modeler to give you phenomenal
results in just 5 minutes! Think of it, 20 dBi from a short Dipole -
but first the story:

While I was pondering the coil current flow tricks, I mused over the
thought of instead loading a short antenna with the inverse of
inductance, capacitance. Instead of using suspect lumped loads, I
instead chose to load the wire with insulation. And not just any
insulation.

Insulation found on typical wire comes in a vary small range of
values. They exhibit dielectric constants from 2 to 4, and rarely
that high. If I were to take a load of it, say in the form factor of
a Texas Bugcatcher coil - what would happen?

Not much it seems. However, I am not one to let that slow me down and
I considered a list of elements and materials to examine them for the
highest DCs available. I was thinking of waxes primarily. The
thought ran that I would turn a small HF antenna into a candle and see
if that would slow the Vf.

Waxes do offer higher DCs, but not markedly so. I started to think
salts next, considering that the common round salt box was about the
same size as a large coil. Salts have a high DC (up to the teens),
but even there, not much effect.

Then I turned to what is commonly available, and exhibits a very high
DC - water (dielectric constant of 80). I started with a meter high
tube of 4 inches diameter (been thinking a lot about plumbing this
week when contractors built a French drain in the basement) and
plunked a short (5M) vertical antenna into it.

THIS made a difference. (OK, so did others, but not like THIS).

What the hell, I started to make the diameter bigger to see where the
limits of failure were. Turned out to be around 12 inches thick water
jacket. This was for a monopole in a truck bed I though (fair amount
of weight and sloshing in this linear load). However, it had the
intended consequence of providing 5.6dBi gain.

Now, this gain has to be taken in the perspective of the unjacketed
radiator that exhibits -4.85dBi gain. More than 10dB gain by adding
this water jacket! Hosanna! Of course, if I trimmed this thickness
to goose up the gain, THEN the modeler failed with reports of negative
resistance (due to possible problems that could not possibly exist).

Well, time to reduce complexity and do the same thing with a short
dipole in space (10M long excited at 3.8MHz). This antenna is
constructed with 10 wires so that only the first wires closest to the
feed are insulated. I increased the size of the water jacket and
noted results for drive point impedance, average gain, and best gain.
The binomial progression is edited from a longer list. The results
are as follows:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
0 4.1 - J 1646 -0.02 1.77
10 3.726 - J 1437 0.039 2.17
20 3.498 - J 1305 0.66 2.45
40 3.2 - J 1133 1.05 2.83
80 2.848 - J 930 1.55 3.34
160 2.46 - J 705.8 2.19 3.98
320 2.051 - J 469.5 2.98 4.77
600 1.67 - J 249.5 3.87 5.66
1211.67 1.238 - J 0.0013 5.17 6.96
2200 0.8685 + J 213.2 6.71 8.5
4000 0.4971 + J 427.7 9.13 10.92
8000 0.0656 + J 676.9 17.93 19.71

As you can see, a water jacket 16 meters wide around the first
meter(s) of the dipole offer considerable gain and nothing suggesting
that further enlargement was going to upset this trend. I wasn't
going to push it anyway because it looked exceedingly suspicious.

As suspicious as it may appear, it shows a rather smooth progression.
It was pleasing to note how the load reactance shifted from capacitive
to inductive. I posted a note to Roy who confirmed the intent for the
insulation entry was to limit it to common coating dimensions.
However, there is nothing in the data to suggest a logic breakdown in
my progressions.

On the other hand, when I pushed this further by reducing the wire
size (10 wires per element instead of 5, while keeping the same total
length), I noticed the effect was more remarkable:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
1000 0.2847 + J 139.9 10.98 12.76

A 1 meter water jacket on a shorter wire induced more gain than the
former 4 meter water jacket from the series of results above.

To me, this suggested a boundary violation more so than a thickness
failure mechanism. There are cautions or prohibitions in connecting
different size wires, it seems that extends to insulations' diameter
mismates even when the wires' diameters (25.4mm) are identical
throughout.

So, the object lesson seems to be
Do not try this at home,
or
in the back yard;
or
Do not fill your truck bed with water flooding your HF antenna

73's
Richard Clark, KB7QHC

p.s.
Just in case there is nothing wrong with the model, I hereby cede this
to the public domain and this is notice of prior art.


I lived near a lake that has about a 3 mile circumference, what kind
of gain could I expect if I sank my antenna in the lake and operated
marine mobile from a wooden boat?


--
73 for now
Buck
N4PGW

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

On Sun, 30 Apr 2006 14:44:29 -0400, Buck wrote:

I lived near a lake that has about a 3 mile circumference, what kind
of gain could I expect if I sank my antenna in the lake and operated
marine mobile from a wooden boat?

Et tu Buck?

Insulation diameter vs Impedance OR how to get 20dBi out of ashort Dipole
 

Richard Clark wrote:
Hi All,

This is a variation on themes being played out. As the title
suggests, you too can force your modeler to give you phenomenal
results in just 5 minutes! Think of it, 20 dBi from a short Dipole -
but first the story:

While I was pondering the coil current flow tricks, I mused over the
thought of instead loading a short antenna with the inverse of
inductance, capacitance. Instead of using suspect lumped loads, I
instead chose to load the wire with insulation. And not just any
insulation.

Insulation found on typical wire comes in a vary small range of
values. They exhibit dielectric constants from 2 to 4, and rarely
that high. If I were to take a load of it, say in the form factor of
a Texas Bugcatcher coil - what would happen?

Not much it seems. However, I am not one to let that slow me down and
I considered a list of elements and materials to examine them for the
highest DCs available. I was thinking of waxes primarily. The
thought ran that I would turn a small HF antenna into a candle and see
if that would slow the Vf.

Waxes do offer higher DCs, but not markedly so. I started to think
salts next, considering that the common round salt box was about the
same size as a large coil. Salts have a high DC (up to the teens),
but even there, not much effect.

Then I turned to what is commonly available, and exhibits a very high
DC - water (dielectric constant of 80). I started with a meter high
tube of 4 inches diameter (been thinking a lot about plumbing this
week when contractors built a French drain in the basement) and
plunked a short (5M) vertical antenna into it.

THIS made a difference. (OK, so did others, but not like THIS).

What the hell, I started to make the diameter bigger to see where the
limits of failure were. Turned out to be around 12 inches thick water
jacket. This was for a monopole in a truck bed I though (fair amount
of weight and sloshing in this linear load). However, it had the
intended consequence of providing 5.6dBi gain.

Now, this gain has to be taken in the perspective of the unjacketed
radiator that exhibits -4.85dBi gain. More than 10dB gain by adding
this water jacket! Hosanna! Of course, if I trimmed this thickness
to goose up the gain, THEN the modeler failed with reports of negative
resistance (due to possible problems that could not possibly exist).

Well, time to reduce complexity and do the same thing with a short
dipole in space (10M long excited at 3.8MHz). This antenna is
constructed with 10 wires so that only the first wires closest to the
feed are insulated. I increased the size of the water jacket and
noted results for drive point impedance, average gain, and best gain.
The binomial progression is edited from a longer list. The results
are as follows:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
0 4.1 - J 1646 -0.02 1.77
10 3.726 - J 1437 0.039 2.17
20 3.498 - J 1305 0.66 2.45
40 3.2 - J 1133 1.05 2.83
80 2.848 - J 930 1.55 3.34
160 2.46 - J 705.8 2.19 3.98
320 2.051 - J 469.5 2.98 4.77
600 1.67 - J 249.5 3.87 5.66
1211.67 1.238 - J 0.0013 5.17 6.96
2200 0.8685 + J 213.2 6.71 8.5
4000 0.4971 + J 427.7 9.13 10.92
8000 0.0656 + J 676.9 17.93 19.71

As you can see, a water jacket 16 meters wide around the first
meter(s) of the dipole offer considerable gain and nothing suggesting
that further enlargement was going to upset this trend. I wasn't
going to push it anyway because it looked exceedingly suspicious.

As suspicious as it may appear, it shows a rather smooth progression.
It was pleasing to note how the load reactance shifted from capacitive
to inductive. I posted a note to Roy who confirmed the intent for the
insulation entry was to limit it to common coating dimensions.
However, there is nothing in the data to suggest a logic breakdown in
my progressions.

On the other hand, when I pushed this further by reducing the wire
size (10 wires per element instead of 5, while keeping the same total
length), I noticed the effect was more remarkable:

Thickness Zfeed AvGain Gain
mm Ohms dB dB
1000 0.2847 + J 139.9 10.98 12.76

A 1 meter water jacket on a shorter wire induced more gain than the
former 4 meter water jacket from the series of results above.

To me, this suggested a boundary violation more so than a thickness
failure mechanism. There are cautions or prohibitions in connecting
different size wires, it seems that extends to insulations' diameter
mismates even when the wires' diameters (25.4mm) are identical
throughout.

So, the object lesson seems to be
Do not try this at home,
or
in the back yard;
or
Do not fill your truck bed with water flooding your HF antenna

73's
Richard Clark, KB7QHC

p.s.
Just in case there is nothing wrong with the model, I hereby cede this
to the public domain and this is notice of prior art.

Hi Richard,
try titanium dioxide next time. As long as you're looking
for absurdist solutions it should work even better than water.
73,
Tom Donaly, KA6RUH

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

On Sun, 30 Apr 2006 21:11:57 GMT, "Tom Donaly"
wrote:

try titanium dioxide next time. As long as you're looking
for absurdist solutions it should work even better than water.

Hi Tom,

For those who don't know, titanium dioxide's dielectric constant runs
about 110.

If I wanted to be truly absurd, I would have done it with Hydrocyanic
Acid (DC of 158), or less aggressively with 35% Hydrogen Peroxide
(121), or back to the acids with Sulfuric Acid (100).

As far as being absurd, yes, this does qualify in spades. However, I
found I could reduce the size of a 40M antenna to nearly half by
surrounding the entire radiator with a water jacket only 40cM thick.
It has a good match, and loses roughly a quarter dB to the full size
antenna. It remains to be seen if this is just another aberration, or
is an actual solution.

73's
Richard Clark, KB7QHC

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

However, I
found I could reduce the size of a 40M antenna to nearly half by
surrounding the entire radiator with a water jacket only 40cM thick.
It has a good match, and loses roughly a quarter dB to the full size
antenna. It remains to be seen if this is just another aberration, or
is an actual solution.

73's
Richard Clark, KB7QHC

Surely it is your model that is an aberration. Did it include such things as
the loss tangent of the dielectric and the effects of the resistivity of the
liquid ?

Di-electric loading is a valid concept, but it has to be done sensibly, and
modelled even more carefully, taking ALL the effects of the di-electric into
account. GIGO.

Regards
Jeff

Insulation diameter vs Impedance OR how to get 20dBi out of ashort Dipole
 

Jeff wrote:

Surely it is your model that is an aberration. Did it include such things as
the loss tangent of the dielectric and the effects of the resistivity of the
liquid ?

Di-electric loading is a valid concept, but it has to be done sensibly, and
modelled even more carefully, taking ALL the effects of the di-electric into
account. GIGO.

The flaw is that the "wire insulation" feature of EZNEC is valid only
for thin coatings, such as those typically found on insulated wire. I
suspect it may also be invalid also for extreme values of dielectric
constant. I don't at present know exactly at what thickness or
dielectric constant the calculation becomes invalid, so results from
models with exceptionally thick and/or high dielectric insulation should
be viewed with some skepticism.

These limitations aren't spelled out in the EZNEC manual, an oversight
on my part for which I apologize. They will be included in the next
update to the manual, which will probably be included with the next
program update (v. 4.0.27).

Roy Lewallen, W7EL

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

On Mon, 1 May 2006 09:10:06 +0100, "Jeff" wrote:

Surely it is your model that is an aberration. Did it include such things as
the loss tangent of the dielectric and the effects of the resistivity of the
liquid ?

Hi Jeff,

An aberration was already included in the list of possible outcomes. I
did not include such things as you suggest because there was no
mechanism to. However, de-ionized water is not that hard to come by,
but would certainly lose that characteristic quickly. As de-ionized
(and further treated) water has none of the defects you anticipate, I
certainly didn't lose sleep in the prospects of its use in HF.

Further, I do have access to a bulk of work employing water loaded
antennas (peer reviewed and not just more vanity publishing) that can
be used to test reality against theory (as corrupted as it may be by
the aberration factor).

73's
Richard Clark, KB7QHC

Insulation diameter vs Impedance OR how to get 20dBi out of a short Dipole
 

"Richard Clark" wrote in message
...


Further, I do have access to a bulk of work employing water loaded
antennas (peer reviewed and not just more vanity publishing) that can
be used to test reality against theory (as corrupted as it may be by
the aberration factor).

73's
Richard Clark, KB7QHC

OK, here is the one for the experienced and theoriticians:

How about antenna made of wires, submerged just below the surface of water,
partially salinated (brakish) or sea water. Would it couple to this huge
"water antenna" (variations of insulated vs. bare elements) or connect/tap
to it?

One experience in this area was, when I operated from VE1ZZ on 160, he has
one Eu Beverage that is terminated on the stainless steel hubcap in the
ocean. That sucker beats any other "superior" beverages (staggered or phased
pairs).

Yuri, K3BU