RadioBanter - View Single Post - How to model a 6:1 ratio balun using NEC2

June 22nd 06, 08:42 PM posted to rec.radio.amateur.antenna

wrote:
Hi Roy,

Yeah, I just started a thread a few days ago regarding current vs.
voltage baluns with respect to my OCF Dipole. I started to play with
around with modeling feedline radiation following the notes on Cebik's
page about it. Doesn't seem like its really possible to accurately
predict the SWR/bandwidth when you start trying to model feedline
radiation too.

Very carefully modeling the very simple OCF Dipole I have assuming no
feedline radiation yields a SWR curve over the HF band that is no-where
near my real world measured values. The NEC2 computed values are much
higher.

That's no surprise. Assumptions that the feedline won't radiate and that
the balun effects a 6:1 impedance transformation regardless of impedance
are both invalid. Garbage in, garbage out.

Roy Lewallen, W7EL