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

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

Yuri Blanarovich wrote:

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?

I don't understand. You're asking about the coupling between a submerged
antenna made of wires and a "water antenna"? What's a "water antenna"?
How close together are the two antennas?

Any submerged antenna would have to be very shallow if it's to receive
signals from above the water -- the attenuation of fields traveling
through salt water is very high (~16 dB/foot at 1.8 MHz). If it's very
deep, it might as well not be there at all.

Roy Lewallen, W7EL

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

On Mon, 1 May 2006 17:24:48 -0400, "Yuri Blanarovich"
wrote:

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?

Hi Yuri,

Sure.

73's
Richard Clark, KB7QHC

"Ocean as antenna"
 

Let me change the subject, in order not to interfere with original thread.

OK, let me try to elaborate based on what I know and have observed.

We know about the effect of distilled water on submerged radiator, it
shrinks the dimensions due to dielectric constant. I am not going to distill
the Barnegat Bay.

We know that salt water or brackish water have high conductivity and act to
radio waves as reflector and we can take the advantage of this property by
using suitable antenna over or next to it.

There is low penetration of such water surface by radio waves, but there
should be some RF currents induced close to the surface of said water, (da
poor conductor).

The question:
is there concentration of induced RF currents near the surface, and if so,
can we tap them by furnishing proper antenna - transducer?
It may be that the whole sandwich of water is just shunted to ground, or is
there enough resistance between the ground and surface to allow enough of
workable current/signal to collect.
The idea is to "gamma match" the giant "water antenna" which is the water
surface, in similar fashion as it is done say with aircraft body surface and
a slot (antenna).

I do not remember this mentioned in the books I have and I wonder if it is
possible to harness the ocean as an antenna. Jus' wanted to make sure we do
not overlook potential "antenna" at our feet.

73 Yuri, K3BU




"Roy Lewallen" wrote in message
...
Yuri Blanarovich wrote:

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?

I don't understand. You're asking about the coupling between a submerged
antenna made of wires and a "water antenna"? What's a "water antenna"? How
close together are the two antennas?

Any submerged antenna would have to be very shallow if it's to receive
signals from above the water -- the attenuation of fields traveling
through salt water is very high (~16 dB/foot at 1.8 MHz). If it's very
deep, it might as well not be there at all.

Roy Lewallen, W7EL

"Ocean as antenna"
 

On Mon, 1 May 2006 19:32:20 -0400, "Yuri Blanarovich"
wrote:

The question:
is there concentration of induced RF currents near the surface,

Hi Yuri,

Certainly. More so above the surface than below. It stands to reason
as that was the best way for it to get beneath the surface by coming
in from above. Now, if you are searching for another trapped layer
for RF, you have to allow that seawater is pitifully lossy even if it
does present a huge shiny interface. Anything "trapped" in it is
consumed by it in very few feet.

An RF wave has to overcome a huge mismatch to get any power into the
sea. Over the entire HF band that SWR is a minimum 19:1. In the 160M
band the SWR is 75:1.

73's
Richard Clark, KB7QHC

"Ocean as antenna"
 

Sorry for the top post.

can the premise be restated as follows:

"Could an insulated wire in a lossy conductive medium [AKA ocean water]
near the surface be modeled as a slot antenna in a lossy plane?"

+ + +

Yuri Blanarovich wrote:

Let me change the subject, in order not to interfere with original thread.

OK, let me try to elaborate based on what I know and have observed.

We know about the effect of distilled water on submerged radiator, it
shrinks the dimensions due to dielectric constant. I am not going to distill
the Barnegat Bay.

We know that salt water or brackish water have high conductivity and act to
radio waves as reflector and we can take the advantage of this property by
using suitable antenna over or next to it.

There is low penetration of such water surface by radio waves, but there
should be some RF currents induced close to the surface of said water, (da
poor conductor).

The question:
is there concentration of induced RF currents near the surface, and if so,
can we tap them by furnishing proper antenna - transducer?
It may be that the whole sandwich of water is just shunted to ground, or is
there enough resistance between the ground and surface to allow enough of
workable current/signal to collect.
The idea is to "gamma match" the giant "water antenna" which is the water
surface, in similar fashion as it is done say with aircraft body surface and
a slot (antenna).

I do not remember this mentioned in the books I have and I wonder if it is
possible to harness the ocean as an antenna. Jus' wanted to make sure we do
not overlook potential "antenna" at our feet.

73 Yuri, K3BU




"Roy Lewallen" wrote in message
...

Yuri Blanarovich wrote:

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?

I don't understand. You're asking about the coupling between a submerged
antenna made of wires and a "water antenna"? What's a "water antenna"? How
close together are the two antennas?

Any submerged antenna would have to be very shallow if it's to receive
signals from above the water -- the attenuation of fields traveling
through salt water is very high (~16 dB/foot at 1.8 MHz). If it's very
deep, it might as well not be there at all.

Roy Lewallen, W7EL

"Ocean as antenna"
 

"Dave" wrote Sorry for the top post.

can the premise be restated as follows:

"Could an insulated wire in a lossy conductive medium [AKA ocean water]
near the surface be modeled as a slot antenna in a lossy plane?"

+ + +

and...
if there is such an effect what is the best way to "catch the RF waves"
grazing the shining ocean surface. More like - can it work besides just
being modeled?

I have been using "dog loop" antenna, originally RF dog fence around 3/4
acre lot, which is basically wire loop burried about 1 inch below the
surface. It has about 600 ohms and works like a goofy Beverage, low noise
pickup and still delivering reasonable signal on 80/160. That's why this
bugs me, like using floating antenna?

Just wondering if there is any potential in this or if anything was written
up in the antenna books pro or con.

Yuri, K3BU/mm


Yuri Blanarovich wrote:

Let me change the subject, in order not to interfere with original
thread.

OK, let me try to elaborate based on what I know and have observed.

We know about the effect of distilled water on submerged radiator, it
shrinks the dimensions due to dielectric constant. I am not going to
distill the Barnegat Bay.

We know that salt water or brackish water have high conductivity and act
to radio waves as reflector and we can take the advantage of this
property by using suitable antenna over or next to it.

There is low penetration of such water surface by radio waves, but there
should be some RF currents induced close to the surface of said water,
(da poor conductor).

The question:
is there concentration of induced RF currents near the surface, and if
so, can we tap them by furnishing proper antenna - transducer?
It may be that the whole sandwich of water is just shunted to ground, or
is there enough resistance between the ground and surface to allow enough
of workable current/signal to collect.
The idea is to "gamma match" the giant "water antenna" which is the water
surface, in similar fashion as it is done say with aircraft body surface
and a slot (antenna).

I do not remember this mentioned in the books I have and I wonder if it
is possible to harness the ocean as an antenna. Jus' wanted to make sure
we do not overlook potential "antenna" at our feet.

73 Yuri, K3BU




"Roy Lewallen" wrote in message
...

Yuri Blanarovich wrote:

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?

I don't understand. You're asking about the coupling between a submerged
antenna made of wires and a "water antenna"? What's a "water antenna"?
How close together are the two antennas?

Any submerged antenna would have to be very shallow if it's to receive
signals from above the water -- the attenuation of fields traveling
through salt water is very high (~16 dB/foot at 1.8 MHz). If it's very
deep, it might as well not be there at all.

Roy Lewallen, W7EL

"Ocean as antenna"
 

Yuri Blanarovich wrote:
"Dave" wrote Sorry for the top post.
can the premise be restated as follows:

"Could an insulated wire in a lossy conductive medium [AKA ocean water]
near the surface be modeled as a slot antenna in a lossy plane?"

No. To my knowledge, a slot antenna requires a thin plane, which an
ocean doesn't resemble. I imagine you could make one in a solid like a
chunk of metal, but believe that the hole depth would have to be a
substantial fraction of a wavelength.


+ + +

and...
if there is such an effect what is the best way to "catch the RF waves"
grazing the shining ocean surface. More like - can it work besides just
being modeled?

Not sure what effect you mean. But NEC-4 models interactions at, above,
and below a medium like water with reasonable accuracy.

I have been using "dog loop" antenna, originally RF dog fence around 3/4
acre lot, which is basically wire loop burried about 1 inch below the
surface. It has about 600 ohms and works like a goofy Beverage, low noise
pickup and still delivering reasonable signal on 80/160. That's why this
bugs me, like using floating antenna?

I think you'll find that a buried antenna will work more and more poorly
as the ground conductivity gets better and better. As an extreme, how
well do you think it would work if buried in an Earth-sized chunk of metal?

Just wondering if there is any potential in this or if anything was written
up in the antenna books pro or con.

I think you're on your own. The path is clear for you to be the first to
make great discoveries! Just be sure to take a little time off along the
way to do make those coil measurements.

Roy Lewallen, W7EL

"Ocean as antenna"
 

Yuri Blanarovich wrote:
....
and...
if there is such an effect what is the best way to "catch the RF waves"
grazing the shining ocean surface. More like - can it work besides just
being modeled?

From
http://www.mso.anu.edu.au/cas/presents/don.html

I quote
"Joe Pawsey took me up to Dover Heights that first day to the cliff-top
interferometer. It was a very cunning device. As the sun rose above the
ocean there was a reflected ray off the ocean, received by the antenna,
and then the direct ray; this formed an interferometer - like a Lloyds
mirror type thing - this was the array that found that the Crab Nebula
was a radio source, and also did much of the early work on Cygnus"

"Ocean as antenna"
 

"Roy Lewallen" wrote
K3BU:
Just wondering if there is any potential in this or if anything was
written up in the antenna books pro or con.

I think you're on your own. The path is clear for you to be the first to
make great discoveries! Just be sure to take a little time off along the
way to do make those coil measurements.

Roy Lewallen, W7EL

Just stumbled on this item, indicating that youze guyz might be defficient
in more areas and I should revise my treatment of some of your previous
answers.

from Johnson - Jasik, Antenna Engineering Handbook, 2nd Ed., p. 5-21:

"The brevity of this review requires omission of many interesting topics
concerning loop antennas. In recent years, there has been considerable study
of loop antennas in close proximity to or embedded in material media such as
the ocean, the earth, or a plasma. The electrical characteristics of loops
in these instances can be quite different from those of loops in unbounded
free space, as described in this review. The major applications of this work
are in the areas of subsurface communication and detection (geophysical
prospecting).
The loop antenna near a planar interface separating two semi-infinite
material regions, such as the air and the earth, has been investigated
extensively. When the loop is electrically small, it can be approximated by
an elementary magnetic dipole, and the electromagnetic field away from the
loop can be determined from the classical analysis of Sommerfeld. If the
field near the electrically small loop is required, the approximation by a
magnetic dipole may no longer be adequate, and a loop with a finite radius
and a uniform current must be considered. For the electrically large loop
near a planar interface, an analysis that allows a nonuniform current in the
loop, such as the Fourier-series analysis for the circular loop, must be
used."

So this idea goes into "to do" pile to be researched or explored.


73 Yuri, K3BU

"Ocean as antenna"
 

On Tue, 16 May 2006 18:48:27 -0400, "Yuri Blanarovich"
wrote:

Just stumbled on this item, indicating that youze guyz might be defficient
in more areas and I should revise my treatment of some of your previous
answers.

from Johnson - Jasik, Antenna Engineering Handbook, 2nd Ed., p. 5-21:

The product of Xerox....

So this idea goes into "to do" pile to be researched or explored.

Hi Yuri,

Just so you get to that first instead of 'splainin' it.

You might visit the library for a copy of R.W.P. King's "Antennas in
Matter," of which I have a copy. You've gotten the short answer from
us, the long answer doesn't change the outcome.

73's
Richard Clark, KB7QHC

"Ocean as antenna"
 

Richard Clark wrote:
On Tue, 16 May 2006 18:48:27 -0400, "Yuri Blanarovich"
wrote:

Just stumbled on this item, indicating that youze guyz might be defficient
in more areas and I should revise my treatment of some of your previous
answers.

from Johnson - Jasik, Antenna Engineering Handbook, 2nd Ed., p. 5-21:

The product of Xerox....

So this idea goes into "to do" pile to be researched or explored.

Hi Yuri,

Just so you get to that first instead of 'splainin' it.

You might visit the library for a copy of R.W.P. King's "Antennas in
Matter," of which I have a copy. You've gotten the short answer from
us, the long answer doesn't change the outcome.

NEC-4 is a lot less expensive than it used to be, and it can be used to
analyze antennas immersed in water, dirt, or another medium besides air.

As for the complexity of calculating the near field, you can struggle
through the math as suggested by Jasik, or you can let EZNEC do it for
you and get the answer in seconds. EZNEC makes no simplifying
assumptions about the loop size.

Roy Lewallen, W7EL

-Proud to add the title of Yuri "defficient" to my many others. Not
quite the level of being a Reg's Old Wife, but a credit nonetheless.
Thanks, Yuri!