"Art Unwin" wrote in message
...
On Sep 5, 5:37 pm, "christofire" wrote:
"Art Unwin" wrote in message

-- snip --


* I don't doubt that it is possible to obtain results from a computer
program that appear to contradict conventional theory. Interpretation of
what comes out is always the responsibility of the operator so, whilst
anyone can enter parameter values and hit 'go', not everyone will
interpret
the results correctly. In this respect it must help greatly to have a
clear
understanding of the basic principles of how antennas radiate and how the
modelling programs operate; in most cases how the moment method works. My
recommendation, as before, is to read an edition of 'Antennas' by Kraus
(or
an equivalent), cover to cover, before trying to make sense of the output
of
any antenna modelling program. Of course, I realise that some who
'publish'
here feel this would be beneath them, or too hard ... but, really, it is
neither.

My own take on the effect of tilting a vertical antenna is that if its
length is an appreciable fraction of a wavelength then tilting it will
distort its radiation pattern and will upset the uniformity of its
polarisation, which will impose a further effective radiation pattern. If
this results in a bit of gain in one particular direction with respect to
a
particular polarisation then fine, and this may be of some use in amateur
radio service although it isn't how vertical monopoles are most often used
(i.e. their omni-directional pattern is their strength and there are many
other, better ways, to obtain directional patterns).

However, the theory on which all the well-known modelling programs is
based
is the simple stuff described by Kraus, et al, and probably in most cases
follows from the original work that led to NEC
(http://www.nec2.org/other/nec2prt1.pdf). It takes _no_ account of the
Coriolis force or gravity (outside of its impact on the speed of light).
If
such a program produces output that the operator interprets as depending
on
the Coriolis force then, logically, this must be a mistake on the part of
the operator - wouldn't you agree? However, if you believe the theory on
which the program is based is in error then maybe you shouldn't use it.

More to the point, it is common knoweledge that there is no full
understanding of radiation available anywhere. Thus he is asking probing
questions to fill in the
gaps.

* There is sufficient understanding of radiation and antennas out there,
as
widely documented, to have enabled practical radio, radar, and suchlike
for
more than a century. I understand that part of the point of amateur radio
is to encourage experimentation, but I don't understand why experimenters
should wish to shun the accepted, conventional theory and try to come up
with their own, perhaps paraphysical, versions - especially when those
people don't exhibit much understanding of the basics. Maybe they treat
the
subject a bit like art (no pun intended) instead of the science that it
should be.

Personaly I am not willing yet to say antenna programs are at fault
until more explanations come about. Can you explain what he is
commenting upon.?

* It's possible he is being deliberately provocative.

Chris

Chris I assume that you have a computer with an optimizer so you are
aware that it will follow the intent of Maxwells laws. And if you
allow it to do this the input should not be designed for planar forms
but allow the optimizer to do its thing. When it finishes it will
provide a response of 100 percent accountabilityYou know this because
maxwells laws account for all forces such that it then provides a
tipped radiator But if you feel it is operator error then what did
your program supply with that input or is it you do not own or use an
optimizer which seems to be prevalent on this newsgroup. Sooooooo
address the statement made by me and provide an academic response
since all posted on this subject comes back to that simple statement I
made. All the other postings are distortions that have run amoke such
that nobody knows the subject of debate and it has become a joke. Your
input to the statement I am sure from your comments will be academic
in form and greatly appreciated. I am winding this thread down now as
statement made are being attributed to me which is false and errors
are piling up on errors


* I have used NEC professionally and I am aware of some of the lower-cost
derivatives used by amateurs. What I stated before does not conflict with
my experience of using NEC - if I were to tip a vertical element then those
effects would result; there wouldn't be any general improvement in its
performance.

If the program you use shows increased coupling factor in all directions
when you tip a vertical monopole then it, and your interpretation of its
results, is in error. If you run an 'optimiser' and it yields such a result
then the error is widespread in your computing system. The simplest
analysis (using arithmetic) of a tipped-over monopole or dipole will
demonstrate that its pattern in the horizontal plane is no longer uniform so
whatever is gained in one direction is lost elsewhere.

I'm beginning to think that the issue is some kind of arrogance - certain
individuals purporting to know better than the conventional wisdom (when
they probably don't know much of the basics). But I don't really understand
why they do this. Perhaps the volume of responses in this NG is enough to
give them a feeling of importance and, I realise, I'm not helping by adding
to the bonfire!

Chris