I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use? Any that are free?

- Consider that I am pretty much a beginner when it
comes to antennas.
- I am intrested in modeling receiving antennas in the
UHF and VHF bands.
- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.

On 11 May 2009 20:42:45 +0100, Gordon wrote:

I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use?

Hi Gordon,

Use NEC.

Any that are free?

What is your pain worth?

- Consider that I am pretty much a beginner when it
comes to antennas.

Then use the one most mentioned among a group of people who regularly
exchange their work and discuss their results. I won't be coy, it is
called EZNEC. However, that is not the last word in recommendations.

- I am intrested in modeling receiving antennas in the
UHF and VHF bands.

Receiving and transmitting are merely the difference of the PTT
button.

- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

This would demand a modeler with the ability to work with a large
number of "segments." Don't go there until you can build a dipole and
understand how it works in free space, over ground, and across three
orders of frequency change. If you do this first on a simple, cheap
or free modeler; then you will be better educated in what you need in
a tool, and how much to spend if it comes to that.

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.

Good for you for saying that; but rest assured you still will pepper
the group with questions. This is not a past-time that fades over the
weekend.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On 11 May 2009 20:42:45 +0100, Gordon wrote:

I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use?

Hi Gordon,

Use NEC.

Any that are free?

What is your pain worth?

- Consider that I am pretty much a beginner when it
comes to antennas.

Then use the one most mentioned among a group of people who regularly
exchange their work and discuss their results. I won't be coy, it is
called EZNEC. However, that is not the last word in recommendations.

4nec2 also has it's adherents as a front end.

Both are basically good front/back ends to the core NEC engine.


- I am intrested in modeling receiving antennas in the
UHF and VHF bands.

Good.. so you're not looking for handling dielectrics, soil, etc.
Mostly free space models of purely conductors.


Remember that NEC works best with things described as collections of
wires (of various diameters, etc.).

It's not so hot with things like patches, dish reflectors, etc. (except
by modeling them as grids of wires).

On 11 May 2009 20:42:45 +0100, Gordon wrote:

I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use? Any that are free?

- Consider that I am pretty much a beginner when it
comes to antennas.
- I am intrested in modeling receiving antennas in the
UHF and VHF bands.
- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.
I like EZNEC.
There is a Demo program available at http://eznec.com/

On 11 May 2009 20:42:45 +0100, Gordon wrote:

I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use?

Hah. I don't think there's anything this group agrees upon. There
are often as many opinions as there are participants.

Any that are free?

Yep. I use 4NEC2 (because I'm cheap). Lots of examples included for
learning and plagerization.
http://home.ict.nl/~arivoors/
be sure to get both the default version and 3D extensions. Examples
of some of my output at:
http://802.11junk.com/jeffl/antennas/

Another freebee is CocoaNEC for the Mac.
http://homepage.mac.com/chen/w7ay/cocoaNEC/

Yet another free program:
http://mmhamsoft.amateur-radio.ca/mmana/

The free demo version of EZNEC works nicely for simple antennas. There
are also demos for some rather expensive commercial packages, that are
suitable for tinkering and learning.

There are others at the bottom of:
http://en.wikipedia.org/wiki/Numerical_Electromagnetics_Code
and in:
http://www.si-list.net/swindex.html (old but worth reading)
Mo
http://www.dxzone.com/catalog/Software/Antenna_analysis/

- Consider that I am pretty much a beginner when it
comes to antennas.

Learn by Destroying. Design, model, build, test, redesign, repeat.

- I am intrested in modeling receiving antennas in the
UHF and VHF bands.
- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

You'll probably need to convert your surfaces to a wire grid (mesh).
4NEC2 includes a wire mesh generator called a "geometry builder". Some
examples:
http://www.softpedia.com/progScreenshots/4nec2-Screenshot-110359.html

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.

Most basic questions can be answered with RTFM and Learn by
Destroying. Please make a few mistakes on your own before asking.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Gordon" wrote in message
...
I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use? Any that are free?

- Consider that I am pretty much a beginner when it
comes to antennas.
- I am intrested in modeling receiving antennas in the
UHF and VHF bands.
- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.


I would recomend reading both the following books:

http://www.antennex.com/Sshack/tutor.../tutorial2.htm

Frank

Gordon,

The ARRL Antenna Book at $40.00 is an excellent reference and worth the
money all by itself. However, the book includes a CD with EZ-NEC models of
the antennas, and a modified version of EZ-NEC software that allows you to
open/manipulate those models (no limit on # of elements like the "demo"
version - but you cannot save your modified files).

IMHO, this is an excellent way to begin using modeling software, using
existing models, with little or no financial risk (like I said, the book
alone is worth $40). If you decide you like the program, buy it! You can
still access all of the ARRL's models as you experiment and extend its
antennas with models of your own.

I am no expert with this stuff, but I have been using modeling software for
many years. I never begin modeling an antenna from scratch; instead I start
with an existing, similar antenna (one from the ARRL book or from the Cebic
collection) and modify it.

-larry
K8UT
"Gordon" wrote in message
...
I have seen a few antenna modeling programs mentioned here.
Is there any concensus within the group on which one is
better to use? Any that are free?

- Consider that I am pretty much a beginner when it
comes to antennas.
- I am intrested in modeling receiving antennas in the
UHF and VHF bands.
- My big point of couriosity right now is reflectors.
I want to see the effects of various wires, rods, screens,
foil, etc.

I suppose that I could pepper the group with questions.
But, at some point it's best to do my own damn research.