Radiating Efficiency
 

This is fairly trivial Reg. It takes me about 90 seconds to run
the program, analyze the data, and record the results for
each length. I consider this a learning experience. Some
of your requests have forced me to read the NEC manual
and other books I have on modeling.

As a preliminary run I have gone overboard, just to see the
overall trend. The fact is I see nothing dramatic happening
until the radial gets very short. Possibly you can see
regions where I need to concentrate. Obviously most of the steps
are very large, and I may have missed something. I would have
expected to see a phase reversal though.

9m Zin = 101.8 + j 21.7
8m Zin = 100.5 + j 21.5
7m Zin = 100.5 + j 19.0
6m Zin = 105.1 + j 17.8
5m Zin = 110.5 + j 26.1
4m Zin = 97.0 + j 40.2
3m Zin = 70.5 + j 25.9
2m Zin = 67.2 + j 19.6

I did try steps of 0.1 m from 8 m to 6.7 m, and saw nothing
but a progressive trend.

Frank
=========================================
Frank,

I'm pleased to hear this does not involve you in a lot of labour.

Thanks for the additional useful information.

Go back to program Radial_3 for a few minutes and insert our standard
inputs.

Set the number of radials equal to One.

Slowly vary length between 1 and 10 metres while observing Rin + jXin
of the radial system.

Vary length to find maxima and minima in the value of Rin. Max and
min are more pronounced at the shorter lengths due to lower
attenuation.

Remember, the radial ( transmission line ) is open-circuit at the
other end.

There is a minimum of Rin when the radial is 1/4-wave resonant at 2.4
metres.

There is a maximum of Rin when the radial is 1/2-wave resonant at 4.8
metres.

There is another minimum of Rin, but less prominent, when the radial
is 3/4-wave resonant at 7.3 metres.

As length and attenuation along the line increase, the variations of
Rin about its mean become smaller. Eventually, of course, it converges
on Ro, the characteristic impedance. ( Ro is also computed but
remains constant as length is varied.)

There would be a full-wave resonance at approximately 10 metres but it
is damped-down into the noise by the attenuation of about 20 dB at
that length.

Now, what I would like you to do is search for the maxima and and
minima in Rin, with their lengths. using NEC4. At some places you may
have to use increments of 0.1 metres.

If you find any max and minima the values of Rin + jXin will be
different from my program and the lengths at which they occur may also
differ. I would like to use the information to improve the accuracy
of my program on the assumption that NEC4 is more correct when
calculating buried radials.

( In this investigation, you may think it peculiar that lengths as
small as 0.1 metres should be significant at 8 MHz. This is due to
the very low velocity of propagation along buried radials. Program
Radial_3 estimates VF.)
----
Reg.

Radiating Efficiency
 

You have the right reference, K3LC. I think that's the one used in
Devolder's book, Low Band DX'ing.

(I don't have it in front of me at the moment)

73,

....hasan, N0AN
wrote in message
oups.com...
Reg, this whole thread started because bizarre things happen with
Radial_3 with short radials.

You can go ahead and put a caveat in it if you like, but it's wrong at
short lengths and that fact needs to be made clear to users of the
program, before they install a radial system of 120 2m radials on 80m
and find that it's a terrible ground system.

The question that I want answered is how to optimize my radial system,
and I think at this point, I shall be consulting a document entitled
"Maximum Gain Radial Ground Systems for Vertical Antennas" by K3LC.

Anyone have other suggestions for sources of material for optimum
radial selection given a certain length of wire?

73,
Dan

Reg Edwards wrote:
Frank, I am not interested is what happens at very short lengths or
what Radial_3 makes of it.

To determine Zo, start around 10 metres.

If very little happens to input impedance between 10 and and 15 metres
then you already have Zo = Zin = Ro + jXo.

Neither am I interested in efficiency or antenna input impedance..
The problem of Efficiency has already been sorted out.

etc.

Radial attenuation
 

Dear Rich,

Try pulling the other leg - it has bells on it!

Punchinello

Radiating Efficiency
 

Go back to program Radial_3 for a few minutes and insert our standard
inputs.

Set the number of radials equal to One.

Slowly vary length between 1 and 10 metres while observing Rin + jXin
of the radial system.

Vary length to find maxima and minima in the value of Rin. Max and
min are more pronounced at the shorter lengths due to lower
attenuation.

Remember, the radial ( transmission line ) is open-circuit at the
other end.

There is a minimum of Rin when the radial is 1/4-wave resonant at 2.4
metres.

There is a maximum of Rin when the radial is 1/2-wave resonant at 4.8
metres.

There is another minimum of Rin, but less prominent, when the radial
is 3/4-wave resonant at 7.3 metres.

As length and attenuation along the line increase, the variations of
Rin about its mean become smaller. Eventually, of course, it converges
on Ro, the characteristic impedance. ( Ro is also computed but
remains constant as length is varied.)

There would be a full-wave resonance at approximately 10 metres but it
is damped-down into the noise by the attenuation of about 20 dB at
that length.

Now, what I would like you to do is search for the maxima and and
minima in Rin, with their lengths. using NEC4. At some places you may
have to use increments of 0.1 metres.

If you find any max and minima the values of Rin + jXin will be
different from my program and the lengths at which they occur may also
differ. I would like to use the information to improve the accuracy
of my program on the assumption that NEC4 is more correct when
calculating buried radials.

( In this investigation, you may think it peculiar that lengths as
small as 0.1 metres should be significant at 8 MHz. This is due to
the very low velocity of propagation along buried radials. Program
Radial_3 estimates VF.)

Reg,

I have done some computations around a 2 m radial length. I noticed
that I had made an error in my previous calculation at exactly 2 m.

1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank

Radiating Efficiency
 

1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank
======================================
Frank,

Very interesting!

I am plotting graphs of R and jX versus length of radial.

Joining up the dots I expect to see shallow sinewaves superimposed on
fairly level mean values.

At present there is a definite shape of curve appearing in the
reactance values while the resistance values are still fairly level.

As length increases I expect to see something similar happening to the
resistance curve which seems to be in between peaks and troughs.

From now on it seems safe for you to increase length in increments of
0.2 metres. There is no danger of missing peaks and troughs in the
curves.

Please keep up the good work.
----
Reg

Radiating Efficiency
 

"Reg Edwards" wrote in message
...
1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank
======================================
Frank,

Very interesting!

I am plotting graphs of R and jX versus length of radial.

Joining up the dots I expect to see shallow sinewaves superimposed on
fairly level mean values.

At present there is a definite shape of curve appearing in the
reactance values while the resistance values are still fairly level.

As length increases I expect to see something similar happening to the
resistance curve which seems to be in between peaks and troughs.

From now on it seems safe for you to increase length in increments of
0.2 metres. There is no danger of missing peaks and troughs in the
curves.

Please keep up the good work.
----
Reg

1.8 m -- Radial Z = , I have reached 7.4m, but there does not seem
any point in continuing. Let me know what you think.

1.8 m -- Radial Z =
1.8 m -- Radial Z =
1.8 m -- Radial Z =

Radiating Efficiency
 

"Reg Edwards" wrote in message
...
1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank
======================================
Frank,

Very interesting!

I am plotting graphs of R and jX versus length of radial.

Joining up the dots I expect to see shallow sinewaves superimposed on
fairly level mean values.

At present there is a definite shape of curve appearing in the
reactance values while the resistance values are still fairly level.

As length increases I expect to see something similar happening to the
resistance curve which seems to be in between peaks and troughs.

From now on it seems safe for you to increase length in increments of
0.2 metres. There is no danger of missing peaks and troughs in the
curves.

Please keep up the good work.
----
Reg

1.8 m -- Radial Z = , I have reached 7.4m, but there does not seem
any point in continuing. Let me know what you think. It does not
appear to be behaving as I would expect of a transmission line;
but then I have no experience of transmission lines immersed
in a lossy material.

Also note the jump in impedance at 5.6 m. I double checked the
result, and it appears to be correct.

2.8 m -- Radial Z = 67.5 + j 19.2
3.0 m -- Radial Z = 70.6 + j 25.9
3.2 m -- Radial Z = 74.7 + j 31.6
3.4 m -- Radial Z = 79.8 + j 36.0
3.6 m -- Radial Z = 85.5 + j 39.0
3.8 m -- Radial Z = 91.4 + j 40.4
4.0 m -- Radial Z = 97.1 + j 40.2
4.2 m -- Radial Z = 102.0 + j 38.6
4.4 m -- Radial Z = 105.9 + j 35.9
4.6 m -- Radial Z = 108.6 + j 32.7
4.8 m -- Radial Z = 110.1 + j 29.3
5.0 m -- Radial Z = 110.5 + j 26.1
5.2 m -- Radial Z = 110.1 + j 23.3
5.4 m -- Radial Z = 109.2 + j 17.2
5.6 m -- Radial Z = 107.9 + j 19.5
5.8 m -- Radial Z = 106.5 + j 18.4
6.0 m -- Radial Z = 105.1 + j 17.7
6.2 m -- Radial Z = 103.8 + j 17.5
6.4 m -- Radial Z = 102.7 + j 17.6
6.6 m -- Radial Z = 101.7 + j 17.9
6.8 m -- Radial Z = 101.0 + j 18.4
7.0 m -- Radial Z = 100.5 + j 19.0
7.2 m -- Radial Z = 100.2 + j 19.6
7.4 m -- Radial Z = 100.1 + j 20.2
..
..
8.0 m -- Radial Z = 100.5 + j 21.4
..
..
9.0 m -- Radial Z = 101.8 + j 21.7

These data are so close to the center of a Smith Chart
normalized to 101.6 + j 21. Not sure how you
normalize with a complex number, but assume it is
with the magnitude of Z.

Frank

Radiating Efficiency
 

"Frank's" wrote in message
news:H6Mzg.180983$771.142858@edtnps89...

"Reg Edwards" wrote in message
...
1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank
======================================
Frank,

Very interesting!

I am plotting graphs of R and jX versus length of radial.

Joining up the dots I expect to see shallow sinewaves superimposed on
fairly level mean values.

At present there is a definite shape of curve appearing in the
reactance values while the resistance values are still fairly level.

As length increases I expect to see something similar happening to the
resistance curve which seems to be in between peaks and troughs.

From now on it seems safe for you to increase length in increments of
0.2 metres. There is no danger of missing peaks and troughs in the
curves.

Please keep up the good work.
----
Reg

1.8 m -- Radial Z = , I have reached 7.4m, but there does not seem
any point in continuing. Let me know what you think. It does not
appear to be behaving as I would expect of a transmission line;
but then I have no experience of transmission lines immersed
in a lossy material.

Also note the jump in impedance at 5.6 m. I double checked the
result, and it appears to be correct.

2.8 m -- Radial Z = 67.5 + j 19.2
3.0 m -- Radial Z = 70.6 + j 25.9
3.2 m -- Radial Z = 74.7 + j 31.6
3.4 m -- Radial Z = 79.8 + j 36.0
3.6 m -- Radial Z = 85.5 + j 39.0
3.8 m -- Radial Z = 91.4 + j 40.4
4.0 m -- Radial Z = 97.1 + j 40.2
4.2 m -- Radial Z = 102.0 + j 38.6
4.4 m -- Radial Z = 105.9 + j 35.9
4.6 m -- Radial Z = 108.6 + j 32.7
4.8 m -- Radial Z = 110.1 + j 29.3
5.0 m -- Radial Z = 110.5 + j 26.1
5.2 m -- Radial Z = 110.1 + j 23.3
5.4 m -- Radial Z = 109.2 + j 17.2
5.6 m -- Radial Z = 107.9 + j 19.5
5.8 m -- Radial Z = 106.5 + j 18.4
6.0 m -- Radial Z = 105.1 + j 17.7
6.2 m -- Radial Z = 103.8 + j 17.5
6.4 m -- Radial Z = 102.7 + j 17.6
6.6 m -- Radial Z = 101.7 + j 17.9
6.8 m -- Radial Z = 101.0 + j 18.4
7.0 m -- Radial Z = 100.5 + j 19.0
7.2 m -- Radial Z = 100.2 + j 19.6
7.4 m -- Radial Z = 100.1 + j 20.2
.
.
8.0 m -- Radial Z = 100.5 + j 21.4
.
.
9.0 m -- Radial Z = 101.8 + j 21.7

These data are so close to the center of a Smith Chart
normalized to 101.6 + j 21. Not sure how you
normalize with a complex number, but assume it is
with the magnitude of Z.

Reg:

It seems that the Smith Chart must be normalized with a
complex number. As expected, with a very high loss
transmission line, the impedance rapidly spirals towards
the complex Zo. From the data it is not clear what is
really happening, but on the Smith Chart it becomes
very clear. The curve crosses the "Real" axis at: 2.8 m,
5.8 m, and about 9 m. At this point the data are so
close to the Smith Chart center that any more
results are irrelevant. Even without a Smith Chart,
normalization of the data will clearly reveal where the
quarter wave multiples are located.

Frank

Radiating Efficiency
 

Frank,

I don't understand Smith Charts.

But you can tell me what conclusions the charts lead you to believe
about the behaviour of a lossy transmission line of various lengths.

I am concerned with reducing the uncertainty of my program from the
information contained in the graphs of input impedance versus length
which I am now able to complete.

joke I don't suppose you would like to repeat the excercise using a
ground resistivity of 1000 ohm-metres. Or repeating at 20 MHz. joke
----
Reg.



"Frank's" wrote in message
news:1qOzg.181008$771.118115@edtnps89...

"Frank's" wrote in message
news:H6Mzg.180983$771.142858@edtnps89...

"Reg Edwards" wrote in message
...
1.8 m -- Radial Z = 70.17 - j 24.1
1.9 m -- Radial Z = 68.5 - j 19.0
2.0 m -- Radial Z = 67.2 - j 14.2
2.1 m -- Radial Z = 66.2 - j 9.5
2.2 m -- Radial Z = 65.5 - j 5.0
2.3 m -- Radial Z = 65.1 - j 0.6
2.4 m -- Radial Z = 65.0 + j 3.6
2.5 m -- Radial Z = 65.2 + j 7.8
2.6 m -- Radial Z = 65.6 + j 11.7

I can keep going if you think that these are the results
you expected. I am tempted to continue, in steps of
0.1 m, and plotting the results on the Smith Chart.
I expect the data to rapidly spiral to the center of
a chart normalized at 101. 6 ohms.

Frank
======================================
Frank,

Very interesting!

I am plotting graphs of R and jX versus length of radial.

Joining up the dots I expect to see shallow sinewaves
superimposed on
fairly level mean values.

At present there is a definite shape of curve appearing in the
reactance values while the resistance values are still fairly
level.

As length increases I expect to see something similar happening
to the
resistance curve which seems to be in between peaks and troughs.

From now on it seems safe for you to increase length in
increments of
0.2 metres. There is no danger of missing peaks and troughs in
the
curves.

Please keep up the good work.
----
Reg

1.8 m -- Radial Z = , I have reached 7.4m, but there does not seem
any point in continuing. Let me know what you think. It does not
appear to be behaving as I would expect of a transmission line;
but then I have no experience of transmission lines immersed
in a lossy material.

Also note the jump in impedance at 5.6 m. I double checked the
result, and it appears to be correct.

2.8 m -- Radial Z = 67.5 + j 19.2
3.0 m -- Radial Z = 70.6 + j 25.9
3.2 m -- Radial Z = 74.7 + j 31.6
3.4 m -- Radial Z = 79.8 + j 36.0
3.6 m -- Radial Z = 85.5 + j 39.0
3.8 m -- Radial Z = 91.4 + j 40.4
4.0 m -- Radial Z = 97.1 + j 40.2
4.2 m -- Radial Z = 102.0 + j 38.6
4.4 m -- Radial Z = 105.9 + j 35.9
4.6 m -- Radial Z = 108.6 + j 32.7
4.8 m -- Radial Z = 110.1 + j 29.3
5.0 m -- Radial Z = 110.5 + j 26.1
5.2 m -- Radial Z = 110.1 + j 23.3
5.4 m -- Radial Z = 109.2 + j 17.2
5.6 m -- Radial Z = 107.9 + j 19.5
5.8 m -- Radial Z = 106.5 + j 18.4
6.0 m -- Radial Z = 105.1 + j 17.7
6.2 m -- Radial Z = 103.8 + j 17.5
6.4 m -- Radial Z = 102.7 + j 17.6
6.6 m -- Radial Z = 101.7 + j 17.9
6.8 m -- Radial Z = 101.0 + j 18.4
7.0 m -- Radial Z = 100.5 + j 19.0
7.2 m -- Radial Z = 100.2 + j 19.6
7.4 m -- Radial Z = 100.1 + j 20.2
.
.
8.0 m -- Radial Z = 100.5 + j 21.4
.
.
9.0 m -- Radial Z = 101.8 + j 21.7

These data are so close to the center of a Smith Chart
normalized to 101.6 + j 21. Not sure how you
normalize with a complex number, but assume it is
with the magnitude of Z.

Reg:

It seems that the Smith Chart must be normalized with a
complex number. As expected, with a very high loss
transmission line, the impedance rapidly spirals towards
the complex Zo. From the data it is not clear what is
really happening, but on the Smith Chart it becomes
very clear. The curve crosses the "Real" axis at: 2.8 m,
5.8 m, and about 9 m. At this point the data are so
close to the Smith Chart center that any more
results are irrelevant. Even without a Smith Chart,
normalization of the data will clearly reveal where the
quarter wave multiples are located.

Frank

Radiating Efficiency
 

"Reg Edwards" wrote

But you can tell me what conclusions the charts lead you to believe
about the behaviour of a lossy transmission line of various lengths.


Sooo, are we investigating behaviour of lossy transmission lines heating the
worms, aka wire in a dirt, or behaviour of radial within the vertical
antenna, aka the other half of a "dipole" and it's participation in forming
the radiation pattern and effciency?
Helooooo?!? What's next? Shortening the radiator?

As a test case, see how "inefficient" is the 3/8 wave vertical, with 360 3/8
wave radials on 160m.
If your "software" tels me that it will be more efficient with 1 m radials,
you are in for serious reality check.

Yuri, K3BU