Re: NEC-LIST: How to get actual far field value??

Hi, Ed,

NEC4WIN, despite the name, is actually MININEC wrapped up in Windows
with an EXCEL-style geometry input sheet and output data plotting of
patterns and currents in windows.

I don't think NEC2 or MININEC take into account impedance mismatches
between the source and drive point on the antenna; they assume
whatever kind of sources you specify, whether realizable or not, and
put those conditions on the antenna conductors. The reason a small
antenna generates a small field is due to the losses associated with:
(1) the antenna conductor I^2R loss, and (2) the loss in the matching
network between the antenna and source, usually associated with the
inductor losses.

A tiny dipole would have more gain than an isotropic radiator in
certain directions if you could match losslessly into it, and if its
conductors were lossless. This is why some people are trying to make
superconducting HF antennae.

In NEC2, the gain output normalization is described by XNDA in columns
17-20 of the RP card, but I'd like to know the differnce between
"Power Gain" and "Directive Gain." Is "Power Gain" the "Gain" and
"Directive Gain" the "Directivity?" How is the efficiency, (printed
in the NEC output file) accounted for?

There is a program called "NECVIEW" written by the author of NEC4WIN
available as a (very) beta version from his web site
[www.CAM.ORG/~mboukri] as necviewb.zip which sort of runs NEC2 from
windows and plots patterns and currents. Majid Boukri indicated to me
at one time that he did not intend to support this software, but
rather, wants to do a Windows95 version of NEC2.

I'm sorry that this is more like questions than answers!

73, Paul Gili, AA1LL Greenville, NH
paul.e.gili_at_lmco.com
Received on Thu Sep 25 1997 - 10:38:05 EDT