NEC-LIST: Re: NEC-List Digest, Vol 8, Issue 4

General Helix Modeling Question:

I have modeled a simple helix,

Seems nice except that the experimentally determined gains are increasing
with frequency rather than decreasing (infact, almost like the numbers are
reversed, the lowest gain is about 14.4 at 2100 and the highest is about

16.5 at 2300). Comments?

The number of segments within the helix should be adjusted
so that at each turn the adjacent segments are positioned
at the same x,y coordinates. Run the average gain test; you
will see the model is defined as either "Bad", or "Questionable".

Also your source segment -- and its adjacent segments -- should
have the same length as the helix segments. I would also recommend
that a single segment be used as the source; rather than 3.

Although I have not verified all physical parameters you must:
ensure that the segment length to diameter ratio, and distances
between adjacent conductors, meet the minimum NEC requirements.

I am using GNEC 1.6.

Regards,

Frank Meredith

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