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Old March 12th 08, 05:47 AM posted to rec.radio.amateur.antenna
[email protected] mcclements@gmail.com is offline
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First recorded activity by RadioBanter: Jan 2007
Posts: 26
Default From NEC2 to the real world with accuracy

Hi,

So I've spent months, rather years, carefully designing a new 5 band
cubical quad for myself. I've always known that I would use #12 solid
copper wire (not stranded), so that is what I used when running NEC2
to optimize this touchy antenna design (over millions of iterations).

Well, real world things are starting to happen. For wire, I've decided
what I would like to use is an enameled coated copperweld wire. I'll
buy the plain copperweld wire and coat it myself.

So my question is, what is the most accurate way to make sure when I
build the quad that I account for the velocity factor (unknown) of the
wire I use? Should I grid dip the elements and make sure they agree
with my NEC2 model? Can I build a simple loop on a higher frequency
with the wire and then somehow use that information to rescale my wire
lengths? What is the "right" way to do this? I wonder how consistent
velocity factor will be if I do my own coating on the wire....maybe
hand coating is a bad idea for this reason....

I spent a lot of time designing a Yagi with NEC2. I used Leeson's
correction for taper elements and to calculate the effect of the
element to boom mounts. All that attention paid off - I thought my
Yagi lived up to the NEC2 predictions very well.

-Scott, WU2X