Re: NEC-LIST: What am I doing wrong and/or don't understand ?

Arie,

I see you don't have conductor loss in your inputs. Try
that and see what happens. Also, what's the input impedance
look like? The gain you get from NEC is relative to the
input power. If the two antennas have the same pattern, and
no loss is modeled, their efficiencies will be 100 % and
their gains will be the same. However, I bet the SWR on the
one-wire version is a lot worse than that fore the two-wire
version, even with unbalanced currents on the feed-line.

Doug Miron

<4nec2_at_gmx.net> writes:

understand ?

Someone who can give me an answer or suggestions
about what I am doing wrong ?

Below I have listed 2 (simplified) Nec2 models. First a
simple
dipole/inverted-V model, fed with open-wire line.
In the second model I have removed one of de dipole wires to
get a kind of 'zeppelin' antenna. The feedline is left as it
was.

When looking at the far field pattern for at all Thete/Phi
angles
with 5 degree increment, it seems for 90% of the cases the 2
wire
antenne outperforms the 1-wire antenna for some 4-5 dB's.
For those
few angles where the 1-wire antenne outperforms the 2-wire
the
differences are much less.
I am asking myself why the 2-wire antenne seems to work much
better tahn the one-wire antenna.

Probably it's something stupid I have missed, but I still
can not
find out what I it is....

When doing an average-gain test both deliver a value of
about 1.11,
saying one should interpret the results with care...
But, because both models deliver almost the same
average-gain value,
I would think, although maybe a bit doubtfull, both models
can be compared with each other.

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

CM 2-wire model
CE
GW 1 26 -.015 0 2 -.015 0 20.0 6.3e-4
GW 2 26 .015 0 2 .015 0 20.0 6.3e-4
GW 20 1 -.0212837 0 1 .0212837 0 1 6.3e-4
GW 21 6 -.0212837 0 1 -.015 0 2 6.3e-4
GW 22 6 .0212837 0 1 .015 0 2 6.3e-4
GW 31 6 -.015 0 20.0 -.0212837 0 21.0 6.3e-4
GW 32 6 .015 0 20.0 .0212837 0 21.0 6.3e-4
GW 51 258 -44.0 0 15.0 -.0212837 0 21.0 .0005
GW 52 258 .0212837 0 21.0 44.0 0 11.0 .0005
GE
GN 2 0 0 0 14 .006
EX 0 20 1 0 1 0
FR 0 1 0 0 7.05
RP 0 37 73 1000 -90.0 0.0 5.0 5.0

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

CM 1-wire model
CE
GW 1 26 -.015 0 2 -.015 0 20.0 6.3e-4
GW 2 26 .015 0 2 .015 0 20.0 6.3e-4
GW 20 1 -.0212837 0 1 .0212837 0 1 6.3e-4
GW 21 6 -.0212837 0 1 -.015 0 2 6.3e-4
GW 22 6 .0212837 0 1 .015 0 2 6.3e-4
GW 31 6 -.015 0 20.0 -.0212837 0 21.0 6.3e-4
GW 32 6 .015 0 20.0 .0212837 0 21.0 6.3e-4
GW 51 258 -44.0 0 15.0 -.0212837 0 21.0 .0005
GE
GN 2 0 0 0 14 .006
EX 0 20 1 0 1 0
FR 0 1 0 0 7.05
RP 0 37 73 1000 -90.0 0.0 5.0 5.0

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

Thanks in advance
Arie Voors

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