Yagi Design Software

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Dene Oehme:
Hi There,

I want to build a Yagi for some data I TX on 467Mhz at work.  I've run the numbers in three different software packages and get different answers.

I'm looking at a 3/4" (19mm) boom with 3/8" (10mm) elements.  Probably 8 directors.

I've tried
VE3SQB's
http://www.ve3sqb.com/yagi.exe

VK5DJ's
http://vk5dj.mountgambier.org/Yagi/Yagi.html

and K7MEM's
http://www.k7mem.150m.com/Electronic_Notebook/antennas/yagi_vhf.html

All give a different answer.

Can anyone suggest which of these to believe or another source.

Thanks,

Dene
VK5DO

Owen Duffy:
Quote from: VK5DO on March 15, 2010, 09:15:25 PM

...
All give a different answer.

Can anyone suggest which of these to believe or another source.



Hi Dene,

K7MEM purports to design a DL6WU Yagi.

I did some recent work with Ian White (GM3SEK) and Guenter Hoch (DL6WU) and the prog maintained by Ian has been changed to use a method for stacking spacing based on Estimating Beamwidth of DL6WU long boom Yagis for the purpose of calculating an optimum stacking distance. Last time I looked, K7MEM had not caught up with those changes. My design tool at DL6WU Long boom Yagi design tool is current AFAIK.

VK5DJ's tool is I think based on VK3AUU's interpretation of the DL6WU design and produces different dimensions. I gather it is VK3AUU's improvements, but I have never seen a description, and I don't think it declares itself an an 'improved' design.

I don't know about the other tool you mention.

Does that help?

Owen

Dale Hunt:
How critical is your application?  There is no single set of dimensions for yagi designs.
Instead there are a wide range of designs that will work, with some sort of tradeoffs
among gain, input impedance, bandwidth, F/B ratio, etc.  So just because the
various calculators don't give exactly the same result doesn't mean that any of the
resulting designs won't produce an adequate antenna for your needs.

A quick way to assess the differences is to model the yagis and see how they
perform.  While I use EZNEC to do this, a quick way is to use W9CF's online
yagi modeling applet, available here:

http://fermi.la.asu.edu/w9cf/

You can use that to get a sense of how much difference there is in performance
among the results of the various calculators.  (It won't handle stacked antennas,
however.)  You can also use it to scale yagi designs from other frequencies to
465 MHz, such as some of the 432 MHz yagis shown on these sites and others:

http://www.mydarc.de/dk7zb/
http://wa5vjb.com/yagi-pdf/cheapyagi.pdf
http://www.ifwtech.co.uk/g3sek/diy-yagi/index.htm

But I'm sure that Owen's calculator will give you a good implementation of the
DL6WU yagi if you don't want to get overloaded with too many options!

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