Re: NEC-LIST: Twin wire transmission line calculations

I use the following formula for a 2 wire transmission line:

Z = 120 cosh(-1) (D/d)

where D is the center-to-center spacing
and d is the wire/tube diameter

Also, you may use Z = 276 LOG (2D/d) as an approximation.

if square tubing is used, d = 1.18 * side length (this was used based on
previous discussions on this list)

This is implemented in my LPCAD software for DOS/Windows computers. If
you would like a copy of the program, please let me know or download from:
http://www.homestead.com/antennas/files/models.htm.

Roger Cox WB0DGF
Senior Antenna Design Engineer
Telex Communications, Inc.
8601 East Cornhusker Hwy.
Lincoln, Nebraska 68505
http://www.telex.com/wireless
402-465-7084
FAX 402-465-6623

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