The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

Let's kick them around.

Cheers,
John KD5YI

John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

It does.

Let's kick them around.

There is nothing to kick around unless you want to argue about whether
the various NEC implementations provide valid results.

What NEC will tell you is that as the .5 wave dipole gets shorter and
shorter, the resistive part of the antenna impedance decreases and the
capacitive part increases and the patern and maximum gain changes very
slightly.

As the ratio of resistive input impedance to the wire resistance get
smaller, the I^2R losses increase.

But don't let that stop you from doing it.

People often learn much better from actual doing then they do from lectures.

BTW, you have to pay some attention to segmentation and as you get smaller
and smaller the segmentation limits just how accurate the simulation is.



--
Jim Pennino

On 10/10/2014 1:15 PM, John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

Let's kick them around.

Cheers,
John KD5YI

I forgot to add to the second * item, that we could use .5 wavelengths,
..25 wavelengths, .1 wavelengths and .05 wavelengths for comparison purposes.

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.

I forgot to add to the second * item, that we could use .5 wavelengths,
.25 wavelengths, .1 wavelengths and .05 wavelengths for comparison purposes.

In many of the antenna discussions I've read, the term "dipole" is
often reserved for antennas which are of approximately half-wavelength
resonance at the frequency in question.

"Doublet" is used for a center-fed dipole-like antenna of other
lengths... for example, a 40-meter dipole which is actually being used
on 15 meters would be referred to as a doublet. In this sort of
terminology, one could consider a "dipole" to be a particular special
case of a "doublet".

Of course, there's the other school of thought which calls *all* of
these antennas "dipoles" (e.g. a "short dipole" or a "5/4-wave
center-fed dipole".

On 10/10/2014 1:50 PM, wrote:
John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

It does.

Let's kick them around.

There is nothing to kick around unless you want to argue about whether
the various NEC implementations provide valid results.

No. I do not want to argue. If you do not want to participate, please
feel free to not post in this thread. I'm sure that your knowledge will
be gratefully accepted when you post if you can do so in a gentlemanly
manner.

What NEC will tell you is that as the .5 wave dipole gets shorter and
shorter, the resistive part of the antenna impedance decreases and the
capacitive part increases and the patern and maximum gain changes very
slightly.

Not concerned about the pattern.

As the ratio of resistive input impedance to the wire resistance get
smaller, the I^2R losses increase.

Yes, of course. Which changes faster?

But don't let that stop you from doing it.

I have never let other people's opinions stopped me from exploring and
learning.

People often learn much better from actual doing then they do from lectures.

True. Today, however, it is nice to be able to explore so many
configurations without spending a lifetime of climbing trees or erecting
support poles or installing towers, or....

BTW, you have to pay some attention to segmentation and as you get smaller
and smaller the segmentation limits just how accurate the simulation is.

I know how that is done. Is this information for me or the other readers?

On 10/10/2014 1:50 PM, wrote:
John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

It does.

Let's kick them around.

There is nothing to kick around unless you want to argue about whether
the various NEC implementations provide valid results.

What NEC will tell you is that as the .5 wave dipole gets shorter and
shorter, the resistive part of the antenna impedance decreases and the
capacitive part increases and the patern and maximum gain changes very
slightly.

As the ratio of resistive input impedance to the wire resistance get
smaller, the I^2R losses increase.

But don't let that stop you from doing it.

People often learn much better from actual doing then they do from lectures.

BTW, you have to pay some attention to segmentation and as you get smaller
and smaller the segmentation limits just how accurate the simulation is.

Ok, I guess I had hoped to have a good conversation concerning the subject.

Jim has convinced me that it is not a worthwhile effort.

Cheers.

"John S" wrote in message
...

No. I do not want to argue. If you do not want to participate, please feel
free to not post in this thread. I'm sure that your knowledge will be
gratefully accepted when you post if you can do so in a gentlemanly
manner.


A great pity that you did not apply the same to yourself when
contributing to my thread about the medium.

John S wrote:
On 10/10/2014 1:50 PM, wrote:
John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

It does.

Let's kick them around.

There is nothing to kick around unless you want to argue about whether
the various NEC implementations provide valid results.

No. I do not want to argue. If you do not want to participate, please
feel free to not post in this thread. I'm sure that your knowledge will
be gratefully accepted when you post if you can do so in a gentlemanly
manner.

A bit sensitive, are we?

What NEC will tell you is that as the .5 wave dipole gets shorter and
shorter, the resistive part of the antenna impedance decreases and the
capacitive part increases and the patern and maximum gain changes very
slightly.

Not concerned about the pattern.

You should at least be concerned about the maximum gain if for no other
reason than to address claims that very short antennas "do not perform".

As the ratio of resistive input impedance to the wire resistance get
smaller, the I^2R losses increase.

Yes, of course. Which changes faster?

I can't say as I have never plotted the data but it would be informative
if you were to do so if you are going to do this.

I would think a plot of I^2R loss versus length in wavelength for at
least two different wire sizes would be instructive, e.g. #8 and #18.

But don't let that stop you from doing it.

I have never let other people's opinions stopped me from exploring and
learning.

People often learn much better from actual doing then they do from lectures.

True. Today, however, it is nice to be able to explore so many
configurations without spending a lifetime of climbing trees or erecting
support poles or installing towers, or....

Yes, simulations prevent a lot of wasted effort.

I once got a hare brained idea for an antenna and modeled it first.

It turned out to be easy to construct with good gain, but an input impedance
in the order of an Ohm and impractical to feed.

Oh well...

BTW, you have to pay some attention to segmentation and as you get smaller
and smaller the segmentation limits just how accurate the simulation is.

I know how that is done. Is this information for me or the other readers?

For whoever is not aware that such limitations exist.


--
Jim Pennino

John S wrote:
On 10/10/2014 1:50 PM, wrote:
John S wrote:
The thread about a new philosophy was about 246 posts long including the
drift into mechanisms of photons and quarks.

I wish to start this thread by discussing the merits of dipoles with
respect to length. I really don't want to start another thread of
flames. Please help me do this.

Let's confine the discussion to...

* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.
* It may or may not have wire resistance (state your value).
* The source is placed at the center of the antenna.
* There is no transmission line.
* There are no matching devices.
* This is a theoretical discussion but may include practical parameters.

EZNEC or NEC, provides answers to these questions, I think. I will do
some modeling and I'd like to compare my results to other results.

It does.

Let's kick them around.

There is nothing to kick around unless you want to argue about whether
the various NEC implementations provide valid results.

What NEC will tell you is that as the .5 wave dipole gets shorter and
shorter, the resistive part of the antenna impedance decreases and the
capacitive part increases and the patern and maximum gain changes very
slightly.

As the ratio of resistive input impedance to the wire resistance get
smaller, the I^2R losses increase.

But don't let that stop you from doing it.

People often learn much better from actual doing then they do from lectures.

BTW, you have to pay some attention to segmentation and as you get smaller
and smaller the segmentation limits just how accurate the simulation is.

Ok, I guess I had hoped to have a good conversation concerning the subject.

Jim has convinced me that it is not a worthwhile effort.

Cheers.


On the contrary, I think it is quite a worthwile effort especially if
you summarize and publish the results for the benefit of all the arm
wavers saying things like "short antennas are poor radiators".

Then you can discuss real data instead of arguing about what some naif
pulled out of his ass.


--
Jim Pennino

David Platt wrote:
* It is a wire dipole (keep the wire AWG to practical values, please).
* The dipole's length is variable.

I forgot to add to the second * item, that we could use .5 wavelengths,
.25 wavelengths, .1 wavelengths and .05 wavelengths for comparison purposes.

In many of the antenna discussions I've read, the term "dipole" is
often reserved for antennas which are of approximately half-wavelength
resonance at the frequency in question.

That is the amateur radio convention, but not so for a physicist.

When a physicist is talking about 1/2 wave dipoles it is either stated
explicitly or obvious from the context.

"Doublet" is used for a center-fed dipole-like antenna of other
lengths... for example, a 40-meter dipole which is actually being used
on 15 meters would be referred to as a doublet. In this sort of
terminology, one could consider a "dipole" to be a particular special
case of a "doublet".

Again, this is amateur radio convention. I don't think I have ever seen
the term doublet in a "science" publication.

Of course, there's the other school of thought which calls *all* of
these antennas "dipoles" (e.g. a "short dipole" or a "5/4-wave
center-fed dipole".

Yep, like you find in physics books, which BTW will always be center
fed unless otherwise specified.

All this language stuff becomes important if you concider the reading
audience can consist of anyone from someone with a passing interest
and little education to a Sheldon Cooper theoretical physicist.



--
Jim Pennino