Cecil Moore wrote:
Mike Coslo wrote:
Cecil Moore wrote:
You can probably arrive at the same correct technical
conclusions by downloading the free demo version of
EZNEC and selecting the diameter of the conductor.

No doubt, Cecil. Of course this wasn't where the conversation
started at. I haven't tried EZNEC to model a cage antenna, will it do
it? Or do you just make the wires really thick? And how does really
thick wire compare to a cage of the same relative diameter?

You can use the free demo version to model a large diameter
radiator with up to 20 segments. For the actual multi-wire
cage antenna, one would need to spring for the non-free
version which is, IMO, the best bargain in ham radio
antenna simulation software.

No doubt, it is great software.



Why ask questions here when
the answer is available to any individual who springs for
EZNEC?


First thing is that Mr Bloe didn't start the thread off as what the
bandwidth of a cage dipole was. The bandwidth question came later. So
while it is good advice to send someone to EZNEC, it is kind of
presuming the person already knows the answer to their question when you
expect them to *not ask the question* in the first place.

I find the topic interesting, and certainly the feedback I've gotten
from Richard and Roy have been very illuminating. So I encourage more on
the topic.

Sure beats those 2000 post threads we seem to get in here! I'd sooner
see topics such as this than you and W8JI sharpening your claws on each
other......hehe

- 73 de Mike KB3EIA -

On Fri, 18 Aug 2006 11:43:34 -0400, Michael Coslo
wrote:

I find the topic interesting, and certainly the feedback I've gotten
from Richard and Roy have been very illuminating. So I encourage more on
the topic.


Hi Mike,

Going further, as you encouraged, you can observe the caged concept
applied to the Discone antenna at:
http://www.qsl.net/kb7qhc/antenna/Discone/discone.htm

This also shows how well 16 wires approximate a solid, and further, it
also shows how the geometry of the apex angle affects the matching
characteristics. This is shown in 7 Smith charts where that angle
varies from 20° to 90°.

Upon close examination, it appears I report the wrong interval of
frequency sweep as every 0.5 MHz. Certainly the range covers 1 to 30
MHz for them all, but it would appear that I shift to every 0.25 MHz
for 50° through 90°.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Fri, 18 Aug 2006 11:43:34 -0400, Michael Coslo
wrote:

I find the topic interesting, and certainly the feedback I've gotten
from Richard and Roy have been very illuminating. So I encourage more on
the topic.


Hi Mike,

Going further, as you encouraged, you can observe the caged concept
applied to the Discone antenna at:
http://www.qsl.net/kb7qhc/antenna/Discone/discone.htm

Fascinating, and thank you! The discone and the Smith charts for it are
a great graphic tool. I note that your webpage is also featured in
Wikipedia.


This also shows how well 16 wires approximate a solid, and further, it
also shows how the geometry of the apex angle affects the matching
characteristics. This is shown in 7 Smith charts where that angle
varies from 20° to 90°.


Upon close examination, it appears I report the wrong interval of
frequency sweep as every 0.5 MHz. Certainly the range covers 1 to 30
MHz for them all, but it would appear that I shift to every 0.25 MHz
for 50° through 90°.

- 73 de Mike KB3EIA -

It takes a month of Sundays for an expert to enter and interpret the
input/output data of a cage dipole using an Eznec-type program.

The basic characteristics of a cage dipole can be displayed, in
practical terms, in a few seconds by downloading program DIPCAGE2 from
website below.

Vary length and diameter, number and gauge of wires in cage, etc., and
observe how resonant length, bandwidth and SWR change.

Program DIPCAGE2. Its about 1/2-way down the list. Been there for
years!
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

This can be done with any EZNEC program type, including the demo:

1. Click Open.
2. Select BYDipole.EZ and click Open in the file selection dialog box.
3. Click SWR. Enter 14 for the start frequency, 15 for the stop
frequency, and .05 for the frequency step. Click Run.
4. Using the arrow keys or the mouse, move the cursor in the SWR display
to the points where SWR is about 2. These are about 14.1 and 14.75 MHz,
indicating a 2:1 SWR bandwidth of about 650 kHz.
5. Click Wires in the main window to open the Wires Window.
6. In the Diameter column, change the Diameter from #12 to 6 to
represent a 6 inch diameter cage. (Don't put a "#" in front of the 6.)
Press the Enter key to finalize the change.
7. Click SWR. Change the start frequency from 14 to 13 and click Run.
8. In the SWR display, move the cursor as before, and note that the 2:1
SWR bandwidth is now about 1.35 MHz, about twice what it was for the
original antenna made from #12 wire.

Now you're a Reg-certified expert, even if that took you a month of
Sundays to do.

You can also get a great deal of additional information from EZNEC, such
as the feedpoint impedance and SWR at any frequency, the pattern, and
effect of height and ground characteristics.

If that took you a month of Sundays, you might think a bit about what's
reduced your capabilities to that level.

Roy Lewallen, W7EL
-- Certified by Reg as both Old Wife and Expert!

Reg Edwards wrote:
It takes a month of Sundays for an expert to enter and interpret the
input/output data of a cage dipole using an Eznec-type program.
. . .

Dear Roy,

But the subject matter is Cage Dipoles.

How many man-hours would it take a novice to enter into Eznec, two, in
line with each other, spaced apart, cylindrical cages, 2-feet in
diameter consisting of 32, 14-gauge wires, with 4 end rings, with time
required to diagnose and eliminate the dozen or more bugs which are
sure to be introduced.

That is, of course, if the free version will accept such an input.

We will forget the 10-day induction course.

How long would it take an expert like yourself to enter and fully
analyse such a dipole. Bear in mind you would have to enter dipoles
consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4
different wire gauges. And obtain the resonant frequencies, input
impedances and SWRs of all possible combinations.

You will say Eznec is probably more accurate.

But DIPCAGE2 will do the same job in a few minutes with an accuracy
quite good enough for the intended purpose. CB-ers can use it.

With Eznec, before the job was finished I would have forgotten what it
was all about, strayed off course and ventured into magloops.

To keep you happy, I will repeat what I have said before and say that
Eznec does an excellent job in those tasks for which it is primarily
intended. What better compliment? I am not in competition with you.
----
Reg, G4FGQ.
=======================================

"Roy Lewallen" wrote
This can be done with any EZNEC program type, including the demo:

1. Click Open.
2. Select BYDipole.EZ and click Open in the file selection dialog
box.
3. Click SWR. Enter 14 for the start frequency, 15 for the stop
frequency, and .05 for the frequency step. Click Run.
4. Using the arrow keys or the mouse, move the cursor in the SWR
display
to the points where SWR is about 2. These are about 14.1 and 14.75
MHz,
indicating a 2:1 SWR bandwidth of about 650 kHz.
5. Click Wires in the main window to open the Wires Window.
6. In the Diameter column, change the Diameter from #12 to 6 to
represent a 6 inch diameter cage. (Don't put a "#" in front of the
6.)
Press the Enter key to finalize the change.
7. Click SWR. Change the start frequency from 14 to 13 and click
Run.
8. In the SWR display, move the cursor as before, and note that the
2:1
SWR bandwidth is now about 1.35 MHz, about twice what it was for the
original antenna made from #12 wire.

Now you're a Reg-certified expert, even if that took you a month of
Sundays to do.

You can also get a great deal of additional information from EZNEC,
such
as the feedpoint impedance and SWR at any frequency, the pattern,
and
effect of height and ground characteristics.

If that took you a month of Sundays, you might think a bit about
what's
reduced your capabilities to that level.

Roy Lewallen, W7EL
-- Certified by Reg as both Old Wife and Expert!

Reg Edwards wrote:
It takes a month of Sundays for an expert to enter and interpret
the
input/output data of a cage dipole using an Eznec-type program.
. . .

Hi Reg

I sure dont mean to become involved with the discussion on Cage Dipoles,
and which method of analyzing them, is better.
I do want to give some data concerning the time needed to learn to use
EZNEC. It isnt necessary to devote the time of a 10 day course in order to
be able to get alot of good/valuable data from EZNEC.
At Richard Clark's encouragement, I bought Roy's EZNEC program a couple
weeks ago. I was able to get good data from the program that same day,
The program is not mysterious.
I write this post to make it clear that EZNEC can be learned quickly by
anyone who trys, and can be learned in one day. I dont inply that I am a
well qualified EZNEC operator, but I have learned so much about the antenna
I am investigating that I really treasure this EZNEC program, and recommend
it to any HAM who has interest in understanding antennas.

Jerry





"Reg Edwards" wrote in message
...
Dear Roy,

But the subject matter is Cage Dipoles.

How many man-hours would it take a novice to enter into Eznec, two, in
line with each other, spaced apart, cylindrical cages, 2-feet in
diameter consisting of 32, 14-gauge wires, with 4 end rings, with time
required to diagnose and eliminate the dozen or more bugs which are
sure to be introduced.

That is, of course, if the free version will accept such an input.

We will forget the 10-day induction course.

How long would it take an expert like yourself to enter and fully
analyse such a dipole. Bear in mind you would have to enter dipoles
consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4
different wire gauges. And obtain the resonant frequencies, input
impedances and SWRs of all possible combinations.

You will say Eznec is probably more accurate.

But DIPCAGE2 will do the same job in a few minutes with an accuracy
quite good enough for the intended purpose. CB-ers can use it.

With Eznec, before the job was finished I would have forgotten what it
was all about, strayed off course and ventured into magloops.

To keep you happy, I will repeat what I have said before and say that
Eznec does an excellent job in those tasks for which it is primarily
intended. What better compliment? I am not in competition with you.
----
Reg, G4FGQ.
=======================================

"Roy Lewallen" wrote
This can be done with any EZNEC program type, including the demo:

1. Click Open.
2. Select BYDipole.EZ and click Open in the file selection dialog
box.
3. Click SWR. Enter 14 for the start frequency, 15 for the stop
frequency, and .05 for the frequency step. Click Run.
4. Using the arrow keys or the mouse, move the cursor in the SWR
display
to the points where SWR is about 2. These are about 14.1 and 14.75
MHz,
indicating a 2:1 SWR bandwidth of about 650 kHz.
5. Click Wires in the main window to open the Wires Window.
6. In the Diameter column, change the Diameter from #12 to 6 to
represent a 6 inch diameter cage. (Don't put a "#" in front of the
6.)
Press the Enter key to finalize the change.
7. Click SWR. Change the start frequency from 14 to 13 and click
Run.
8. In the SWR display, move the cursor as before, and note that the
2:1
SWR bandwidth is now about 1.35 MHz, about twice what it was for the
original antenna made from #12 wire.

Now you're a Reg-certified expert, even if that took you a month of
Sundays to do.

You can also get a great deal of additional information from EZNEC,
such
as the feedpoint impedance and SWR at any frequency, the pattern,
and
effect of height and ground characteristics.

If that took you a month of Sundays, you might think a bit about
what's
reduced your capabilities to that level.

Roy Lewallen, W7EL
-- Certified by Reg as both Old Wife and Expert!

Reg Edwards wrote:
It takes a month of Sundays for an expert to enter and interpret
the
input/output data of a cage dipole using an Eznec-type program.
. . .

On Sat, 19 Aug 2006 04:16:53 GMT, "Jerry Martes"
wrote:

Hi Reg

I sure dont mean to become involved with the discussion on Cage Dipoles,
and which method of analyzing them, is better.
I do want to give some data concerning the time needed to learn to use
EZNEC. It isnt necessary to devote the time of a 10 day course in order to
be able to get alot of good/valuable data from EZNEC.
At Richard Clark's encouragement, I bought Roy's EZNEC program a couple
weeks ago. I was able to get good data from the program that same day,
The program is not mysterious.
I write this post to make it clear that EZNEC can be learned quickly by
anyone who trys, and can be learned in one day. I dont inply that I am a
well qualified EZNEC operator, but I have learned so much about the antenna
I am investigating that I really treasure this EZNEC program, and recommend
it to any HAM who has interest in understanding antennas.

Jerry

Jerry,

The truth probably lies somewhere between your view and Reg's.

Whilst you may have been able to construct a simple model in a very
short time, being confident that you have a valid model on even modest
antennas takes much more experience and knowledge.

I think it is another of those cases where the more I learn, the less
I know. You may find the same in time.

Owen
--

"Owen Duffy" wrote in message
...
On Sat, 19 Aug 2006 04:16:53 GMT, "Jerry Martes"
wrote:

Hi Reg

I sure dont mean to become involved with the discussion on Cage Dipoles,
and which method of analyzing them, is better.
I do want to give some data concerning the time needed to learn to use
EZNEC. It isnt necessary to devote the time of a 10 day course in order
to
be able to get alot of good/valuable data from EZNEC.
At Richard Clark's encouragement, I bought Roy's EZNEC program a couple
weeks ago. I was able to get good data from the program that same day,
The program is not mysterious.
I write this post to make it clear that EZNEC can be learned quickly by
anyone who trys, and can be learned in one day. I dont inply that I am a
well qualified EZNEC operator, but I have learned so much about the
antenna
I am investigating that I really treasure this EZNEC program, and
recommend
it to any HAM who has interest in understanding antennas.

Jerry

Jerry,

The truth probably lies somewhere between your view and Reg's.

Whilst you may have been able to construct a simple model in a very
short time, being confident that you have a valid model on even modest
antennas takes much more experience and knowledge.

I think it is another of those cases where the more I learn, the less
I know. You may find the same in time.

Owen

Hi Owen

I am not qualified to comment on Reg's information on either computer
programs or antennas in general. I am not far from being a beginer at
antenna design by today's standards. But I was able to get decent data on
a 4 dipole array circularly polarized array that requires some phasing of
the dipoles. By my standards, that isnt a modest antenna. Richard Clark
was god enough to give guidance and encouragement via E-mail. That may
account for my being to get such good data on the first day of trying EZNEC.
But, he didnt actually provide data.
I am not qualified to differ with your observations concerning learning to
use EZNEC. But, as must be clear by now, I am really impresed with this
program and I consider it learnable with a little time and logic. It is
my hope that I can encourage anyone who has interest in antenna design and
understanding to 'give it a try'. It doesnt demand a formal training
course. EZNEC is a nifty tool.

Jerry

--

I find Reg's collection and EZNEC both valuable tools.
There are elements of EZNEC that I have not learned to use.
In Reg's collection each applet has a tight focus.
Yet neither can be considered complete solutions.

I am not certain that I am using either correctly without committing
the calculations to physical models.

de W8CCW John


On Sat, 19 Aug 2006 03:15:07 +0100, "Reg Edwards"
wrote:

Dear Roy,

But the subject matter is Cage Dipoles.

How many man-hours would it take a novice to enter into Eznec, two, in
line with each other, spaced apart, cylindrical cages, 2-feet in
diameter consisting of 32, 14-gauge wires, with 4 end rings, with time
required to diagnose and eliminate the dozen or more bugs which are
sure to be introduced.

That is, of course, if the free version will accept such an input.

We will forget the 10-day induction course.

How long would it take an expert like yourself to enter and fully
analyse such a dipole. Bear in mind you would have to enter dipoles
consisting of 2, 4, 8, 16, 32 and 64 wires, plus end rings, of say 4
different wire gauges. And obtain the resonant frequencies, input
impedances and SWRs of all possible combinations.

You will say Eznec is probably more accurate.

But DIPCAGE2 will do the same job in a few minutes with an accuracy
quite good enough for the intended purpose. CB-ers can use it.

With Eznec, before the job was finished I would have forgotten what it
was all about, strayed off course and ventured into magloops.

To keep you happy, I will repeat what I have said before and say that
Eznec does an excellent job in those tasks for which it is primarily
intended. What better compliment? I am not in competition with you.
----
Reg, G4FGQ.
=======================================

"Roy Lewallen" wrote
This can be done with any EZNEC program type, including the demo:

1. Click Open.
2. Select BYDipole.EZ and click Open in the file selection dialog
box.
3. Click SWR. Enter 14 for the start frequency, 15 for the stop
frequency, and .05 for the frequency step. Click Run.
4. Using the arrow keys or the mouse, move the cursor in the SWR
display
to the points where SWR is about 2. These are about 14.1 and 14.75
MHz,
indicating a 2:1 SWR bandwidth of about 650 kHz.
5. Click Wires in the main window to open the Wires Window.
6. In the Diameter column, change the Diameter from #12 to 6 to
represent a 6 inch diameter cage. (Don't put a "#" in front of the
6.)
Press the Enter key to finalize the change.
7. Click SWR. Change the start frequency from 14 to 13 and click
Run.
8. In the SWR display, move the cursor as before, and note that the
2:1
SWR bandwidth is now about 1.35 MHz, about twice what it was for the
original antenna made from #12 wire.

Now you're a Reg-certified expert, even if that took you a month of
Sundays to do.

You can also get a great deal of additional information from EZNEC,
such
as the feedpoint impedance and SWR at any frequency, the pattern,
and
effect of height and ground characteristics.

If that took you a month of Sundays, you might think a bit about
what's
reduced your capabilities to that level.

Roy Lewallen, W7EL
-- Certified by Reg as both Old Wife and Expert!

Reg Edwards wrote:
It takes a month of Sundays for an expert to enter and interpret
the
input/output data of a cage dipole using an Eznec-type program.
. . .

John Ferrell W8CCW