RE: NEC-LIST: Problem using arcs

Russell,

In your file using arcs, your second GA card is just tracing over top
the structure generated in your first. If you use one GA card with
angles from 0 to 360, you will get a complete circle. In addition,
your total number of segments should be equal to the number used in
your octagonal approximation (24). If you want to get the source in
the same spot as on the octagon (bottom of loop), rotate your 24
segment GA structure by 7.5 degrees about the y-axis and place the
source on segment 19 of the circle. Here's the structure:

CM Circular loop
CM 10 cm radius, 6 mm wire
CE
GA 1 24 .1 0 360 .003
GM 0 0 0 7.5 0 0 0 0 0
GE 0
EX 0 1 19 00 1 0

You don't really need the GS card since NEC works in meters by
default.

To judge whether the number of segments, radius, and segment/radius
ratio are appropriate, I would have to know what your operating
frequency is. You should use segments 0.1 wavelengths long or less,
radius less than 0.01 wavelengths, and segment/radius ratio greater
than 8. In the file above, the segment/radius ratio is about 8.7,
which is fine, but the other two parameters depend on operating
frequency.

Regards,

John Yorko
ITT Industries, Aerospace/Communications Division
Fort Wayne, IN
Received on Wed Dec 09 1998 - 10:32:20 EST