NEC-LIST: EZNEC-Pro and Long Computation Time and other Tid-Bits

Roy,

Last year I made a detailed study of multi-wire fans, like the one
Marconi used for his transatlantic experiments in December 1901. A
multi-wire fan, closed at the top, is a most interesting antenna to
model, since the wire structure carries both trasnsmission-line and
in-phase currents. I had previously numerically and experimentally
modelled multi-wire fans, Marconi was a multi-wire antenna nut --- but
wrt numerically modelling a 54-wire fan I had never made a frequency
analysis --- too long --- it takes my computer about two hours for
each frequency.

So, last Wednesday I programmed EZNEC-Pro for a frequency sweep, 0.4
to 15 MHz, in 0.2 MHz steps, 73 frequencies. I figured this would
take about 6-days. The computer was still thrashing away Monday noon
(telephone call to the Lab) --- and when I came in Tuesday morning the
machine was quiet --- but it had stored all 73 frequency values for
antenna impedance. Great!!

I thought this might amuse you.

The next antenna system I would like to come-to-grips with is the
Corum antenna. You might remember that a few years ago (November
1995) I made comment (posted on this media) on the contrawound
toroidal helix antenna, and on (other) hoax antennas (the cross-field
antenna). Recently Peter Dodd, G3LDO, questioned me about that
comment, and in a follow up, I learned that the inventer of the
self-resonant toroidal helix was James F. Corum, K1AON.

So I wrote Jim, and I received yesterday a fourteen page letter, and a
stack of reprints. Now all I have to do is find the time to gain (if
possible) some understanding of the subject.

The air-wound version could be numerically modelled --- but employing
my simple modelling proceedures this would take some time --- even if
I had a physical antenna to model. Whatever, the subject is still
alive (or revived).

I have added this note to the first part of this message, which was
what I intended to say --- but since I thought I would post the
message --- I continued on on the other subject.

73, Jack

_____________________________________________
John S. (Jack) Belrose, PhD Cantab, VE2CV
Senior Radioscientist
Radio Sciences Branch
Communications Research Centre
PO Box 11490 Stn. H
OTTAWA ON K2H 8S2
CANADA
TEL 613-998-2779
FAX 613-998-4077
e-mail <john.belrose_at_crc.ca>
_____________________________________________
Received on Wed Feb 03 1999 - 16:37:56 EST