Segmentation question, + Eznec
 

Recently got W4RNL's collection of .EZ
models. and many were written for more advanced
versions than my Basic EZ (limited to 500
Segments) And tho, when you reduce those segments
to the limits of 500, And seem to work fine,have 2
DUMB query's about them .

1), when looking at MOST models, they end in a
ODD number of segments, say I reduce those segs
from 19 to 16, for a given wire,,does this make
all that much difference in the calculations?, and

2) as I have gone from ODD number's to an EVEN
numbers, is THIS anything to worry about? Even
with the Driven Element (which, as I see it, would
place the feedpoint (you would expect 50 % off the
ends,IF you use Even # segments, what happens
when the feed is, say 9 (or 4-1/2) segments, at 50
% feed point ?

But other folks might also be curious
about these effects, tho from what I've seen, they
appear minimal. Your thoughts, Please! Jim NN7K

Segmentation question, + Eznec
 

Jim - NN7K wrote:
Recently got W4RNL's collection of .EZ
models. and many were written for more advanced
versions than my Basic EZ (limited to 500
Segments) And tho, when you reduce those segments
to the limits of 500, And seem to work fine,have 2 DUMB query's about
them .

1), when looking at MOST models, they end in a
ODD number of segments, say I reduce those segs
from 19 to 16, for a given wire,,does this make all that much
difference in the calculations?, and

No, but you need an odd number of segments if you want to put a source,
load, etc. at the middle of a wire.

2) as I have gone from ODD number's to an EVEN numbers, is THIS
anything to worry about? Even with the Driven Element (which, as I see
it, would place the feedpoint (you would expect 50 % off the ends,IF you
use Even # segments, what happens
when the feed is, say 9 (or 4-1/2) segments, at 50 % feed point ?

Sorry, I don't understand the question.

. .

Roy Lewallen, W7EL

Segmentation question, + Eznec
 

Thanks , Roy, and let me try to rephrase #2, with
my poor anylitical mind. IF you feed a dipole ,
dead center, on a wire that has an ODD length of
segments, how does that compair to a dipole of
EVEN segments (mathamatically)?
In other words we are describeing a DIPOLE
(balanced feed), with 6 segments (3+, and 3- at
the feedpoint), with a dipole with 7 Wires (
3-1/2 , vs - 3, 1/2 segments, at the same feed
point, or am i tilting at windmills?

Guess the best bet is to make sure Segments ALL
odd numbers!
Jim


2) as I have gone from ODD number's to an EVEN numbers, is THIS
anything to worry about? Even with the Driven Element (which, as I
see it, would place the feedpoint (you would expect 50 % off the
ends,IF you use Even # segments, what happens
when the feed is, say 9 (or 4-1/2) segments, at 50 % feed point ?

Sorry, I don't understand the question.

. .

Roy Lewallen, W7EL

Segmentation question, + Eznec
 

Think see my error- thinking FULL wave on element,
NOT 1/2 Wave! maybe that where i confused ! Jim

Roy Lewallen wrote:
Jim - NN7K wrote:
Recently got W4RNL's collection of .EZ
models. and many were written for more advanced
versions than my Basic EZ (limited to 500
Segments) And tho, when you reduce those segments
to the limits of 500, And seem to work fine,have 2 DUMB query's about
them .

1), when looking at MOST models, they end in a
ODD number of segments, say I reduce those segs
from 19 to 16, for a given wire,,does this make all that much
difference in the calculations?, and

No, but you need an odd number of segments if you want to put a source,
load, etc. at the middle of a wire.

2) as I have gone from ODD number's to an EVEN numbers, is THIS
anything to worry about? Even with the Driven Element (which, as I
see it, would place the feedpoint (you would expect 50 % off the
ends,IF you use Even # segments, what happens
when the feed is, say 9 (or 4-1/2) segments, at 50 % feed point ?

Sorry, I don't understand the question.

. .

Roy Lewallen, W7EL

Segmentation question, + Eznec
 

Jim - NN7K wrote:

Thanks , Roy, and let me try to rephrase #2, with my poor anylitical
mind. IF you feed a dipole , dead center, on a wire that has an ODD
length of segments, how does that compair to a dipole of EVEN segments
(mathamatically)?
In other words we are describeing a DIPOLE (balanced feed), with 6
segments (3+, and 3- at the feedpoint), with a dipole with 7 Wires (
3-1/2 , vs - 3, 1/2 segments, at the same feed
point, or am i tilting at windmills?

Guess the best bet is to make sure Segments ALL odd numbers!
Jim

EZNEC places a source or other object at the center of a segment, as
close as it can to the position you specify. If a wire has an even
number of segments and you specify the wire center (50% of the way from
end 1), the object will be placed at the center of one of the segments
adjacent to the center of wire, a position which is 1/2 segment from the
center of the wire. If the wire has 10 segments, this will result in the
object being placed 5% of the wire length off center. If the wire has
100 segments, it'll be off center by 0.5%. This typically won't have
much effect on the model results, except that you might see a bit of
asymmetry in the pattern and some change in impedance compared to
putting the object in the center of the wire.

The EZNEC manual discusses segmentation at some length.

Roy Lewallen, W7EL