IMPORTANT NOTICE about atlc
Author: Dr. David Kirkby, drkirkby@ntlworld.com
Description: atlc - Important notice
Keywords: atlc arbitrary transmission line any cross section

# IMPORTANT NOTICE

Many of the examples in the documentation were produced with atlc prior to verision 4.0.0. Versions prior to 4.0.0 are only capable of analysing two-wire transmission lines, such as coax, twin-wire or any other lines with two conductors. The only impedance pre version 4.0.0 executables will give is the characteristic impedance Zo, since that is all is defined for such a stucture.

Versions of atlc 4.0.0 and later can handle 3-wire transmission lines too (a directional coupler). Such a 3-wire coupler has both an odd mode and an even mode impedance defined, in addition to Zo, so atlc must print those too. However, these other impedances (Zodd and Zeven) are meaningless for 2-wire transmission lines, such as coax. or other two-wire transmission lines.

I took the decision to still print Zodd and Zeven, at all times, (even with 2-wire lines) so if anyone writes scripts that read the output files, they can be sure the answers remain in the same column, independant of the type of structure. i.e. Zo is always in the 11th column, no matter what the structure. This may cause some confusion, but please ignore the columns for Zodd and Zeven for normal transmission lines. Please just ignore the Zodd and Zeven outputs, unless analysing directional couplers.

Analysing a simple coax prior to version 4.0.0 will give

`coax2.bmp Er= 1.0000 C= 47.6374 pF/m L= 233.5667 nH/m Zo= 70.0215 Ohms v= 2.99792e+08 m/s v_f= 1.0000 VERSION= 3.0.6`

versions 4.0.0 and later will give

`coax2.bmp Er= 1.0000 C= 47.6374 pF/m L= 233.5667 nH/m Zo= 70.0215 Ohms Zodd= N/A Ohms Zeven= N/A Ohms v= 2.99792e+08 m/s v_f= 1.0000 VERSION= 4.0.0`

Analysing a coupler in version 4.0.0 will give the following output, where the even and odd mode impedances are given too.

`coupler1.bmp Er= 1.0000 C= 50.8316 pF/m L= 218.8893 nH/m Zo= 64.9952 Ohms Zodd= 64.3750 Ohms Zeven= 65.6213 Ohms v= 2.99792e+08 m/s v_f= 1.0000 VERSION= 4.0.0`

I hope it does not cause undue confusion, but I'm sure you realise it does make life easier when trying to read the text files in another programme, when you can be sure the positions of answers don't change with different stuctures.

atlc is written and supported by Dr. David Kirkby (G8WRB) It it issued under the GNU General Public License

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