I used the 'help' menu in Agent, but it doesn't seem to let me post an
attachment.

In order to post a jpg you would need to essentially convert it to
text. I think a program called uuencode does it.
Then it comes out looking like 15,000 lines of garbage to anyone
reading the articles here. It would make you a lot of enemies faster
than calling CQ on 14336.

Put it another way - the rec.radio newsgroups are text only.

Rick K2XT

Guys:

FYI...

Walt is correct. This "rec.radio.amateur.antenna" USENET NG (aka "rraa") and
many other newsgroups redact any graphics, attachments or inserts associated
with NG posts, allowing only text to be posted. This practice is followed
of course in the interests of both memory and bandwidth conservation at the
"free" USENET servers. No one running USENET servers makes money!

However, a number of years ago a special USENET newsgroup was set up by
USENET volunteers in the "alt.binaries" area, to be used for short term
postings of graphics content related to electronics such as schematics,
etc...

There are a couple of minor problems associated with this approach. (1) For
one, the biggest problem is that not all ISPs actually carry the
"alt.binaries" groups due to either, server memory limitations or, because
several (many?) alt.binaries groups carry pornograhic graphics. (2) The
second small "problem" is that, again for reasons of memory conservation,
the "turnover" of postings on those graphics/binaries groups is fairly high.
That is postings are cycled through fairly quickly, usually with
availability of only a week or so. And so one should surf on over to the
alt.binaries group quickly to view or download any desired postings.

All that said however, ya'll should find that
"alt.binaries.schematics.electronics" (aka "abse") is a good place to post
drawings, schematics, block diagrams, photos and other graphics content
related to electronics and antennas, etc.

The usual procedure in the "electronics" groups such as
"sci.electronics.design" (aka "sed") is to mention that the
graphics/schematic referred to in your postings, has been posted on the
other NG that accepts graphics/binaries.

For example lots of the folks who hang out and discourse on:
"sci.electronics.design" (aka "sed") post their schematics, block diagrams,
photos, etc... to "alt.binaries.schematics.electronics" (aka "abse").

There is no reason why the denziens of "rraa" cannot post their antenna
graphics on "abse".

Sign up for abse and... Go for it... just do it!

Hope this helps. :-)

--
Pete k1po
Indialantic By-the-Sea, FL

"Walter Maxwell" wrote in message
...
On Tue, 08 Aug 2006 16:39:13 GMT, "Frank's"
wrote:

"Walter Maxwell" wrote in message
. ..
On Tue, 8 Aug 2006 15:39:16 +0100, "Reg Edwards"

wrote:

Any Tom, Dick and Harry can copy and build a circuit out of a book.

But it takes a top-class engineer just to look at a strange circuit
and describe what it does, how it works.

These days, there are mostly Tom's, Dick's and Harry's!
====================================
Amendment -

For "circuit" read "antenna".

"Tom's, Dick's and Harry's" has replaced "old wives". ;o) ;o)

====================================

Hello Reg,

I haven't previously tried to attach a jpg file in this arena, but I'm
going to
try. If my jpg file comes through, can you describe what it does and how
it
works?

Walt, W2DU

Rats, now you have me intrigued Walt. Too bad the pic did not work.
Just tried to post a picture, but it seems there is a filter on the NG to
prevent such postings.

Reg, have made a lot of progress in developing a NEC 4 model
of a 100 radial system. Just have to iron out a few bugs. When this
is completed I can try some high frequency models.

Frank

Hi Frank,

I used the 'help' menu in Agent, but it doesn't seem to let me post an
attachment. Guess, like you said, it must be an NG rule that prevents it.
Anyhoo, jist fertheleovit, I'm going to email you the jpg file fyi.

Walt, W2DU

On Tue, 08 Aug 2006 16:39:13 GMT, "Frank's" wrote:

"Walter Maxwell" wrote in message

Rats, now you have me intrigued Walt. Too bad the pic did not work.
Just tried to post a picture, but it seems there is a filter on the NG to
prevent such postings.

Reg, have made a lot of progress in developing a NEC 4 model
of a 100 radial system. Just have to iron out a few bugs. When this
is completed I can try some high frequency models.

Frank

Frank, I tried to send the jpg file to you via email, but the server rejects
your address. Can you email me so I can have your correct address?

Walt

Frank's wrote:
Just tried to post a picture, but it seems there is a filter on the NG to
prevent such postings.

Yep, this newsgroup was chartered as ASCII only.
--
73, Cecil http://www.qsl.net/w5dxp

On Tue, 08 Aug 2006 16:39:13 GMT, "Frank's"
wrote:
[snip]

Rats, now you have me intrigued Walt. Too bad the pic did not work.
Just tried to post a picture, but it seems there is a filter on the NG to
prevent such postings.

Reg, have made a lot of progress in developing a NEC 4 model
of a 100 radial system. Just have to iron out a few bugs. When this
is completed I can try some high frequency models.

Frank

Walt was nice enough to send me the graphic and, so others can see it,
I've placed it on my web page for your viewing pleasure.

http://k6mhe.com/sub/w2du_engineering.jpg

Note: This will available for about 30 days.

Danny, K6MHE

On Tue, 08 Aug 2006 14:34:50 -0700, Dan Richardson
wrote:

Walt was nice enough to send me the graphic and, so others can see it,
I've placed it on my web page for your viewing pleasure.

http://k6mhe.com/sub/w2du_engineering.jpg

"There cannot be a greater mistake than that of looking superciliously
upon practical applications of science. The life and soul of science
is its practical application."
- Bill Thomson

Reg, have made a lot of progress in developing a NEC 4 model
of a 100 radial system. Just have to iron out a few bugs. When
this
is completed I can try some high frequency models.

Frank
=========================================

Frank, don't forget to use a 1/4-wave vertical when calculating
efficiency.

I assume you always include the power in the ground wave in the total
power radiated when calculating efficiency.

I think radial length intervals of 0.5 metres will be OK for 100 or
more radials.
----
Reg.

Frank, don't forget to use a 1/4-wave vertical when calculating
efficiency.

I assume you always include the power in the ground wave in the total
power radiated when calculating efficiency.

I think radial length intervals of 0.5 metres will be OK for 100 or
more radials.

Reg,

I have always used the 1/4 wave vertical to calculate efficiency.
Most of my calculations do not include the surface wave. The problem
with including the surface wave is that it is computed over a cylindrical
surface at x meters from the antenna. Technically not a surface, but
rather a vertical line in cylindrical coordinates. The surface is implied
due to the expected symmetry of radiation. In my calculations I have
taken "x" as 200 m, so as to ensure the result is in the far-field at 8 MHz
(nominal 5 wavelengths). I compute the field at 1 m intervals, in the "z"
direction to 200 m. To include the total field I would have to allow z
to approach infinity. Taking these data from the NEC output text file, I
import it to Excel. In Excel I compute the radial distance and elevation
angle to the source. Since my increments are in steps of one meter
I can only approximate integral degree points; removing those points
far from integral degrees. I could employ
linear interpolation, but the field intensity variation is relatively
smooth,
and adds no discernable ripple to the radiation pattern. I then
normalize these data to 1 m to match the spherical data for the
sky wave pattern. At 45 degrees elevation there is very little
ground wave effects, I can then combine the two normalized
sets of data, and numerically integrate over a hemispherical surface.

Sorry to bore you with these details, but just to give an idea of
the tedious steps involved in including the surface wave. To compute
the total radiated sky wave involves a simple command in NEC.
Just the same I can compute the total radiated power at 0.5 m
and 10 m radial lengths as a comparison. At every 0.5 m it would
drive me nuts.

Attempting to model a 100 radial system I continually run into
road blocks. At one point I had a complex matrix with 3.6
million entries. Still I think I have a viable model that needs
just a little refinement. Due to the rotational symmetry of the
structure I can employ methods that greatly reduce run time. The
model that should work will consist of thirty-three 10 cm
radials. At the end of these short radials I connect three 9.9 m
radials for a total of 99 radials. If I run into problems I may
have to reduce the segmentation to 25 cm. What is interesting,
in my preliminary results, is that there is only a 2% improvement
in sky wave total radiated power with 120 radials over 36 radials.

Frank

"Frank's" wrote
Reg,

I have always used the 1/4 wave vertical to calculate efficiency.
Most of my calculations do not include the surface wave. The
problem
with including the surface wave is that it is computed over a
cylindrical
surface at x meters from the antenna. Technically not a surface,
but
rather a vertical line in cylindrical coordinates. The surface is
implied
due to the expected symmetry of radiation. In my calculations I
have
taken "x" as 200 m, so as to ensure the result is in the far-field
at 8 MHz
(nominal 5 wavelengths). I compute the field at 1 m intervals, in
the "z"
direction to 200 m. To include the total field I would have to
allow z
to approach infinity. Taking these data from the NEC output text
file, I
import it to Excel. In Excel I compute the radial distance and
elevation
angle to the source. Since my increments are in steps of one meter
I can only approximate integral degree points; removing those points
far from integral degrees. I could employ
linear interpolation, but the field intensity variation is
relatively
smooth,
and adds no discernable ripple to the radiation pattern. I then
normalize these data to 1 m to match the spherical data for the
sky wave pattern. At 45 degrees elevation there is very little
ground wave effects, I can then combine the two normalized
sets of data, and numerically integrate over a hemispherical
surface.

Sorry to bore you with these details, but just to give an idea of
the tedious steps involved in including the surface wave. To
compute
the total radiated sky wave involves a simple command in NEC.
Just the same I can compute the total radiated power at 0.5 m
and 10 m radial lengths as a comparison. At every 0.5 m it would
drive me nuts.

Attempting to model a 100 radial system I continually run into
road blocks. At one point I had a complex matrix with 3.6
million entries. Still I think I have a viable model that needs
just a little refinement. Due to the rotational symmetry of the
structure I can employ methods that greatly reduce run time. The
model that should work will consist of thirty-three 10 cm
radials. At the end of these short radials I connect three 9.9 m
radials for a total of 99 radials. If I run into problems I may
have to reduce the segmentation to 25 cm. What is interesting,
in my preliminary results, is that there is only a 2% improvement
in sky wave total radiated power with 120 radials over 36 radials.

Frank
======================================

Frank,

Radiating efficiency is of secondary importance. It does not change
very much with length of radials except at very short lengths.

If computing efficiency involves great labour then do it at infrequent
intervals.

What IS important is the input impedance of a collection of N radials
versus length, frequency and ground characteristics. From which
efficiency can be calculated if required.

I know not, and do not need to know, the details of how you use NEC4.
I think it is safe to assume NEC4 provides reasonably correct answers.

After all, the primary purpose of NEC4 is to generate radiation
patterns from highly suspect input data. And I'm sure approximations
are involved somewhere. When a camel is designed by several
committees in succession, who knows how many humps can appear?

I am about to delete all contents of these threads. I look forward to
seeing a message from "Frank's".
----
Reg, G4FGQ.

On Tue, 8 Aug 2006 15:39:16 +0100, "Reg Edwards"
wrote:

Any Tom, Dick and Harry can copy and build a circuit out of a book.

Hi Reggie,

You prove you can write in English, but equally proven is that this
post is as obscure as reading Beowulf. However, it is equally notable
that most English speakers have some of the poorest grammar:
These days, there are mostly Tom's, Dick's and Harry's!
where possessive case substitutes for plurals.

Is this the standard troll, or whining? Do you somehow feel
disappointed that Engineers don't create art? Has your esteem for
British luminaries suddenly dimmed by their lack of imagination?

I for one cannot imagine Bill Thomson sitting on a Parisian sidewalk
doing chalk copies of renaissance art - unless he was anticipating
your holiday so as to wing that chalk off your noggin.

Or perhaps you pine for the lost opportunity of Auguste Rodin
sculpting Pascal code out of marble. Whoops! A frog there. Perhaps
a Tom Gainsborough sloshing the paint to rummage up an astable
multivibrator.

Oh for the days when they were mostly Toms, Bills, and Augustes....
and Marcels - "À la Recherche du Temps Perdu" Now there's a French
sleeping pill no engineer would copy.

73's
Richard Clark, KB7QHC