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Old March 12th 08, 04:58 PM posted to rec.radio.amateur.antenna
Art Unwin Art Unwin is offline
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First recorded activity by RadioBanter: Mar 2008
Posts: 1,339
Default From NEC2 to the real world with accuracy

On Mar 12, 10:22 am, wrote:
On Mar 12, 11:01 am, Art Unwin wrote:

Scott, you are introducing sharp corners to your new antenna so NEC
will stray from accuracy.


Is NEC4 better in this regard?

Here is the NEC2 reported performance of my current design. Its a 24
foot boom, with 5 bands. 4 elements on 15-10 and 3 elements on 20-17.
Optimization is for F/R around mid-band and bandwidth (under 2.5:1 at
edges).

http://remote.wu2x.com:8888/WU2X/

Click each band.html file to see the graphs on each band. The non-
active driven elements are shorted.

Here is the stock Cubex 4 element quad, which is 4 elements on all
bands (on a 24' boom).

http://remote.wu2x.com:8888/Cubex/

-Scott, WU2X


I would suggest that you check with what Cebik says about it.
At the same time you are also now dealing with vertcal polarisation
which also has a lot of characteristics that are different from planar
yagis where the elements are not in equilibrrium as compared to a quad
design.
One can discharge corona where the other doesn't soto use the same
calculations
for designs that behave differently raises a lot of questions besides
the sharp corners.
Niether of the programs are perfect but better than shooting in the
dark.
Art