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Re: [TowerTalk] C31XR versus SteppIR

To: Kelly Taylor <>
Subject: Re: [TowerTalk] C31XR versus SteppIR
From: David Gilbert <>
Date: Sun, 13 May 2007 16:52:49 -0700
List-post: <>
I don't disagree with most of what you've said about actually getting 
out there and building antennas.  It's a huge part of the enjoyment I 
derive from this hobby.

That being said, it's not easy to compare one antenna to another unless 
they are up at the same time on towers separated far enough to minimize 
interaction.  And under the best of circumstances, antenna pattern is 
difficult to experimentally determine.  On the air performance is a nice 
indicator, but unless you're willing to test a particular antenna over a 
long period of time, propagation and other factors cloud the results 
(witness some of the ridiculous claims for antennas on this and other 
forums).  Modeling with one version of NEC or other, taking into account 
known errors and limitations, is (in my opinion) more likely to give 
valid comparisons between various designs. 

But the biggest reason I would urge anyone interested in antennas to 
experiment with modeling is precisely because of what you learn.  I have 
been a ham for 40 years and have built almost every kind of antenna 
except rhombics and LPDAs, but I learned more the first year I owned 
EZNEC than I did the previous 30 years worth of experimenting.  There is 
simply so much information available from a model ... antenna pattern, 
effects of phasing, current distributions on the elements, impact of 
length and spacing changes ... that you can't help but learn a lot if 
you make a point of understanding what you get.  There isn't the same 
ability to measure all those things (i.e., current magnitude or phase in 
the top leg of a delta loop) in real life.  If I build an antenna and it 
doesn't perform very well, I don't have the same ability to figure out 
why as I do if I am able to model it.

I just don't see the point of making it an either/or situation between 
modeling and practice.

Dave   AB7E

Kelly Taylor wrote:
> I'm not going to enter any debate on the merits of modelling. Like I said, 
> if it's what you like to do, do it. But for those on the reflector who may 
> have forgotten that learning about radio is part of what ham radio is about, 
> go have fun with your antennas. Learn from what works and what doesn't. For 
> someone who is still learning, it's the most effective way to learn, even if 
> it's not the most effective way to get a killer antenna.
> 73, kelly
> ve4xt 
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