[TowerTalk] Modeling a Yagi in EZNec

[john at kk9a.com]

That is something I have also thought about.  I do not include the balun
lead wires.  They are likely part of the transmission line but if not, a
short 90° segment like that may still may not model correctly in NEC2.  I
use OWA designs and so even if the lead wires had some effect, I adjust the
driven element for the desired SWR pattern anyway.  Typically I see SWR
curves very close to my EZNEC model with very little adjustment.

John KK9A


Tom K0SN wrote:

Those who use NEC to model a yagi, do you include the lead lengths in the
model for the connecting wires that go from the balun to the feed terminals
of the driven element?
If so, do you model them as part of the element itself or as a transmission
line?
My leads are 4" long. So if I model them as part of the element, I would
just describe the center portion of the element to be an 8" piece of say,
#12 wire, then the next portion of the element would contain the correction
for the element to boom clamps.
Do I have this right or am I overthinking it?
My goal is to get the model perfected to the point that when I actually
build the beam, I will not have to make adjustments in the lengths of the
driven elements to bring them to resonance.
Maybe that's an unreasonable expectation, or not?

Any input appreciated.

Tom Hellem
K0SN