re: NEC-LIST: vertical monopole impedance

>From the desk of Keith Lysiak <KLysiak_at_swri.edu>

I tried varying the radius with both NEC-3 (a derivative of NEC-2) and
NEC-4 using a fixed length. Both tracked each other and varied
significantly in impedance and resonant frequency. On the other hand,
if you re-trim the wire for each radius back to resonance, the
impedance will remain relativily constant.

End of Message

---------- Original Text ----------

From: "Rick Karlquist" <rick_at_area.com>, on 9/17/1999 3:53 AM:
To: Incognito2_at_CTC@SwRI26[<nec-list_at_ee.ubc.ca>]

I ran some EZNEC simulations of ~1/4 wave monopoles over perfect
ground. According to the program, if you shorten the monopole just
enough to achieve resonance, the impedance is 36.0 ohms, independent
of diameter for a range of diameters from 0.00001 to .02 wavelengths.
This doesn't agree with any textbooks on the subject that I have read.
Are the textbooks all wrong, or is this an NEC-2 limitation (or did I
goof up somewhere). I tried various numbers of segments and it
doesn't seem to affect the results.

Rick Karlquist N6RK
rick_at_area.com
Received on Thu Sep 23 1999 - 01:57:04 EDT