Re: NEC-LIST: (Boeingj 747)Phase of currents on wires?

Peter,

Some quick suggestions and comments

> I am trying to build a wire frame model of a 747. I have the model
> and am trying to determine if it is valid. Freq. of interest is 2
> MHz and segments are between 9 and 20 inches with the majority
> between 15 and 20. No segment is longer than 20 inches.

Download the free SuperNEC demo from

http://www.poynting.co.za/emsoft/supnec/sndisk/supernec.zip

and use the built in checker. The demo is limited to 300 segs (for
running) but will check and display larger problems. It should load a
normal NEC file. Our SuperNEC program has a built in checker which
uses NEC2 rules and some user guidelines. It checks for many error
conditions (segment length, length and radius ratios, thickness,
overlapping segs, near misses, extreme angles resulting in observation
point containment, duplicate segments etc). Most of these rules were
published by Trueman and Kubina in ACES magazine - they also sell a
program to check geometries

> > It appears that the phase of the current on a wire is in
> > reference to the wire direction.

Quite correct. The end 1 and end 2 is used to define direction. If for
example you put two excitations on two segments and both are 1 V angle
0, but you have reflected them round a plane (for example) you have
two antennas with 180 degrees phase shift. Quite a subtle modeling
error and I have personally seen it a few times.

Regards
Andre Fourie

Tel: Intl + 27 11 4030380
Fax: Intl + 27 11 4030381
Website: http://www.poynting.co.za
email: fourie_at_poynting.co.za
Papermail: Dr APC Fourie, PO Box 318, Wits, 2050, South Africa
Received on Thu May 25 2000 - 12:19:12 EDT