Thierry wrote:
Thanks for all comments.

I did a mistakle in my specs because they are no traps on the windom (I
confused with W4DZZ).

In fact I thought that both designs being wire antennas of almost the same
length, they 'd display the same radiation pattern at a few percent.
But I was focused on the shortest segment (1/3) of the windom and wonder
whether it could cause or not additional problems or display drawbacks
compared to a real dipole...
In all case I will test it in 2 weeks.
Problem with dipole3, the influence of a shorter segment is not taken into
account. I don't know if that could be important, probably not much, but it
'd have been interesting to add some additional parameters like the length
of each segment and the tilt of the tilt too to get a more accurate result.

Addition:
My believe is founded. I just find some radiation patterns and comments in
the ARRL antenna book ch7-8. The windom is much more omnidirectional than a
dipole. They say that "the system (windom) takes advantage of the asymmetry
of the horizontal wires to induce current onto the braid of the vertical
coax section.... The radiation pattern... tends to fill in the deep nulls
that 'd be present ... if horizontally center fed".
globally they consider that the windom give better results due to the
omnidirectional pattern or so than a true dipole.
Anyway, if I have the courage I will try to simulate the windom in Multinec.


Thanks for the help
Thierry, ON4SKY


"Reg Edwards" wrote in message
...

Taking one band with another and one direction with another, the

difference

between a Windom and G5RV will be entirely undetectable.

They will both have somewhat poorer performance than a simple random

length

dipole of about the same length and height fed over a random length, high
impedance, any Zo, open-wire line.

Following the study you have given to the subject, you may be disappointed
at the responses to your question, But you did ask.

And there's no reason why you should be deterred from experimenting with
either or both types of antenna. You will then be at least as wise as us
Old Wive's.

If you should like playing with just a few numbers then amuse yourself

with

small programs DIPOLE3 and ENDFEED. Download from website below in a few
seconds and run immediately. They provide lots of data but the most
important thing is the single number - radiating efficiency!
---
................................................ ...........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
................................................ ...........





Hi Thierry:

The only draw back of the off center fed dipole is the possibility of
introducing radiation from the feedline which can make for R.F. in the
Shack if not properly acconted for , it also makes predicting the
radiation pattern a little skewed to the long end of the dipole. I Use
two off center fed dipoles (miss nomer windoms) here one is cut for 40m
long the other 20m long the 40m long one is fed with a 4:1 balun and 75
ohm coax the 20m long is fed with 300 ohm open wire line to a tuner.
both antennas do a good job for me. I do mostly causual dxing (but as
one poster has already said you'll have to decide which propagation mode
you are seeking if grayline put up a vertical or other lowangle radiator
for 80meters.) They are mounted at 90 degrees to each other. I've been
able to work lots of dx on these antennas .. I had two g5rv's up prior
to these and from a pure operational veiw point find them a little
better at my location.

hope this is of some help.
73 Dave