This is a special purpose calculator which performs simple transmission line calculations. Given three line parameters, the Widget calculates the value of a fourth. Two formulae are used, one for coaxial cable, the other for parallel line.
When the Widget is started, it displays a window with four fields. Enter data into the three white fields, then press the RETURN or ENTER key. The Widget computes the other value and displays it in the fourth field.
Which of the four values is to be computed can be set by clicking on the Output Mode menu button.
The Widget uses two formulae, one for coaxial cable, the other for parallel line. The formula to be used can be chosen by clicking on the Input Mode menu button from which the input mode (Coaxial Cable or Parallel line) can be chosen.
For coaxial cable, the formula used is: Z0 = Zv * ln(o / i) / (2 * π * sqrt(e)),
where Zv is the characteristic impedance of a vacuum, o and i are the outer and
inner cable radii, e is the relative permittivity of the dielectric, and Z0 is
characteristic impedance of the transmission line.
For parallel line, the formula used is: Z0 = Zv * ln(s/r) / (π * sqrt(e)), where
Zv is the characteristic impedance of a vacuum, s and r are the line separation
and line radius, e is the relative permittivity of the dielectric, and Z0 is
characteristic impedance of the transmission line.
The value of Zv is taken to be 376.73031346177066 ohms.
Because the measurements of length only appear in the ratios (o / i) and (s / r), they can be in any units desired, provided the same units are used for both.
The Tx Line Calculator is Copyright © 2007-2015 Harry Whitfield (G6AUC).
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA