Hey, Jonathan,
That is exactly how you are to do it. One point though, you do
not have to specify the exact segment to place it. Just give the
LOAD window a "percentage from the end" and it will place it
close enough. However, If you do have the 500 segment version you
can place it exactly where you wish by using many segments to
define the element.
Definitions and How To's --- In EZNEC, go to Help/Contents and
click on LOADS / RLC and LOADING COILS and also
TRAPS. There are good explanations of each implementation and
probably more detail than you want if you follow all of the
subsequent links.
GL and 73...rick
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On Wed, Dec 2, 2020 at 10:13 AM Jonathan Guthrie via BVARC
<bvarc@bvarc.org <mailto:bvarc@bvarc.org>> wrote:
I got a question about analyzing antennas with traps and loading.
If you're familiar with the book "The Short Vertical Antenna
and Ground Radial" by Sevick, I simulated one of the antennas
he wrote about in an NEC2 system and I think I got it right,
but the way that you put traps and loading coils and such
into NEC is not well described anywhere that I could find,
nor are there many examples with simple antennas that have
any loading coils. If you're not familiar with the book, or
you're interested in which antenna, Sevick describes a 40m
antenna that's right at 6 feet tall with a cap hat on the top
and a loading coil in the middle. The way I modeled this is
by having a single wire from near the ground to the top of
the antenna and then one wire for each of the eight spreaders
in the cap hat and a wire between each of the ends of the
spreader. I arranged the elements such that the coil is near
the center of one of the segments in the vertical wire and I
put a lumped inductance on that segment. It seems to work,
in that I got SWR curves that are similar to what's in the
book, but is that how you're supposed to do it?
Similarly, with a trap dipole, I just have one wire and put
an appropriate capacitor and inductor in parallel at the
center of the desired segments.
On 12/1/2020 8:35 PM, Rick Hiller via BVARC wrote:
Comments on your suggestions: Sorry for the length.
*MiniNEC, EZNEC, 4NEC2, MMANA-GA*L are all based on the NEC
computation engine. What differs is the interface to you,
the user. I prefer EZNEC but then I have been using it for
about 20 years.
Cost for the Ham Radio level versions: EZNEC DEMO is free
but with severe limitations for all but very simple
antennas. $99 gets you to a quite useable version. 4NEC2 is
totally free. MiniNEC is $29. MMANA-GAL is 139 Euro's,
There are PRO versions and interface add-ons from various
3rd parties for most of the modeling engines. Just like my
comment about the Nano VNA, in that it's gonna take some
time to understand its' use and even more time to study
antenna systems to understand what you are doing and why and
how -- same goes for modeling software. But....certainly
all in good fun and ham education and well worth the journey.
*Folded dipoles a*re simply a way to get a match to 300 ohm
TL. No advantage in gain , etc. Maybe slightly quieter
on receive...maybe. TTFD is a different fish.
*Books: *ARRL Antenna Handbook is certainly the antenna
builders/users bible. You can however buy the Kindle
version of each of the separated set books, so you don't
have to spend the $60. Most of the theory is the same in
these new editions versus going back to the 70's and
before. The practical side of antennas with new materials,
etc. is what gets upgraded with each new edition. Old
versions of the ARRL antenna manual can be had for $10
typically. You can't go wrong buying any older version.
If I had to steer you to books to read to get you up to
speed about your total antenna system -- ATU, TL, tools, and
grounding, I would tell you to get the following ARRL Joel
Hallas and Ward Silver books:
The Care and Feeding of Transmission Lines -- Hallas
Understanding your Antenna Analyzer -- Hallas
ARRL Guide to Antenna Tuners -- Hallas
Grounding and Bonding for the Radio Amateur -- Silver
I'd tell you to read and understand these before jumping
into a NanoVNA, of which there is also a small book on the
use of the NanoVNA. Kindle version available for $4 or
thereabouts.
Sorry for the bandwidth, but I don't agree with just buying
something just because it is suggested. There is alot to
learn in Amateur Radio and it is certainly fun to have a
continual information influx throughout the life of your Ham
Radio journey. But watching the $'s helps you buy bigger
toys later on.
GL ES 73....Rick -- W5RH
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On Tue, Dec 1, 2020 at 1:16 PM KJ Anderson via BVARC
<bvarc@bvarc.org <mailto:bvarc@bvarc.org>> wrote:
* MiniNEC pro analyzer
o
http://www.blackcatsystems.com/software/mininec-antenna-analysis-modeling-software.html
<http://www.blackcatsystems.com/software/mininec-antenna-analysis-modeling-software.html>
* DX Commander
o https://www.m0mcx.co.uk/ <https://www.m0mcx.co.uk/>
* Folded dipoles (couldn’t google a site reference
other than the actual antenna form)
* EZNEC
o https://www.eznec.com/ <https://www.eznec.com/>
o There’s a free version
* ARRL Antenna Physics
o
http://www.arrl.org/shop/Antenna-Physics-An-Introduction-2nd-Edition/
<http://www.arrl.org/shop/Antenna-Physics-An-Introduction-2nd-Edition/>
o http://www.arrl.org/shop/ARRL-Antenna-Book-Boxed-Set/
<http://www.arrl.org/shop/ARRL-Antenna-Book-Boxed-Set/>
*-------------------------------------------------*
*KJ Anderson*
253-380-2636
www.linkedin.com/in/scrumnerd
<http://www.linkedin.com/in/scrumnerd>
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--
Rick Hiller
*/e-mail: rickhille...@gmail.com
<mailto:rickhille...@gmail.com>/*
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*/Physical: 9031 Troulon Drive/*
*/ Houston, TX 77036/*
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*/e-mail: rickhille...@gmail.com <mailto:rickhille...@gmail.com>/*
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*/ Houston, TX 77036/*
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