Vertical Antenna Performance Question
 

"Buck" wrote in message
...
On Sun, 17 Feb 2008 02:11:56 GMT, "Jerry"
wrote:


I have some limited accuracy test equipment for evaluating antennas.
Recently Richard Clark prodded me till I couldnt take it any more so I got
some of Roy's software. Richard even told me how to use it. It has
become
clear that *my* test equipment is is very good agreement with Roy's EZNEC.
. EZNEC works so well for my situation that I thought it was woring well
for
everyone. I can make real radiation patterns of my prototype antennas
(using POES signals for the illuminator) that are in agreement with EZNEC
prediction. Even the inpedance of the eklements are well predicted by
EZNEC. Do you know where any real data is in disagreement with EZNEC
predictions? I'd like to know more about any data anyone has that shows
where EZNEC gives wrong data.

Jerry KD6JDJ (who is extreemely happy with his EZNEC
"tool")



I believe there are still a lot of unknowns about antenna theory and
propagation and that something may someday come along that EZNEC
cannot properly calculate and model. There are several hams who may
or may not be lurking about this group that have invented 'new'
antenna designs that cannot be properly modeled by EZNEC.
Unfortunately, for the ones I know about, the information is held so
secretly close to the inventors that their designs cannot be properly
compared to other antennas of known design to validate the inventors'
claims.

I have been a ham for 29.5 years now and for HF base, I have almost
exclusively operated from my own home-brew antennas. I learned a few
things over the years, rules of thumb so to speak. For Yagi antennas,
the longer the boom, the greater the gain, the shorter the boom, the
wider the beam width. For wire antennas, (within certain constraints)
the more wire, the more gain, the longer the antenna, the better the
gain, the shorter the antenna (shortened antenna) the narrower the
bandwidth. It is very hard to get a 1/16th wave antenna to work as
well as a decent 1/2 wave antenna for the same frequency. Most
importantly, any antenna (that won't destroy the radio) will
communicate given adequate propagation between the two points.

I don't use EZNEC. I haven't had the time set aside for studying that
and antenna theory long enough to make good use of the program. I have
tried, but it isn't capable of modeling the antenna design that I want
to experiment with,

I don't say this to discredit Roy, as, in all honesty, from the bottom
of my heart, I acknowledge that by far he has greater intelligence in
the antenna field than I hope to have. But, his software has certain
limitations and he states at least some of the limitations in his user
manual.

There are a number of professional antenna specialists here, some
real, some wanna-be. Some of those professionals don't care for us
amateurs being here asking questions anyone with a Masters degree in
antenna science shouldn't have learned by their fifth or sixth year of
study. Others are glad to help as long as we have shown to have made
some effort to understand the basics of how an antenna works.

I have respect for both Roy and Cecil, even tho they are quite often
at odds with each other, and I have respect for others here as well.
In time you will know who you want to trust and who you don't want to
hear from.

Good luck,
Buck
N4PGW

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Hi Buck

My comments related to computer modeling are directed to the validity of
the EZNEC results. I want to support the fact that it works. There is no
question that there may be some concepts that EZNEC cant deal with. My
thoughts about EZNEC relate to its ability to give good answers to questions
with which it is intended to be used. I consider the EZNEC program to be
quite accurate for the VHF antenna concepts I work with. I worked fairly
consistently for a couple years on an antenna design concept that was
written up in the Feb 2008 QST and consider EZNEC to be responsible for my
being able to better understand the concept. I would certainly never be
without the program, now that I have used it.

Jerry KD6JDJ