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Noncylindrical ConductorsAuthor: Edmund A. Laport
An example of this process is the case of two parallel flat strips of half thickness p with spacing a, used as a balanced transmission line.
The numerical results of each step only are included. The dimensions used are as follows (see Fig. 6.6): Thickness 0.031 inch ( ρ = 0.0155 inch) Width 0.500 inch Spacing 0.500 inch between center lines In step 1, the extremities of each strip are replaced by four wires of diameter equal to the thickness of the strips and having the same outside dimensions. Solving this as a balanced line,
In step 2, another wire is placed midway between each of the above pairs and given the same potentials, and for this step Z_{0} = 185 ohms. The charge ratios for step 3 (Fig. 6.6) for the inner wires are found to be Q_{3}/Q_{1} = 0.418 and Q_{2}/Q_{1} = 0.600. The computed value Z_{0} = 178 ohms. These values can now be plotted in Cartesian coordinates. If we call N the number of wires in one side of the circuit and plot the computed values of Z_{0} against 1/N, as in Fig. 6.7, the ultimate value of a continuous strip of wires conforming to the originally desired flat strips can be found at the intersection of this curve with the value 1/N = 0. This value is seen to be about 175 ohms. The process can be applied to complex surfaces such as angles, channels, or other structural forms which are much more complicated than this simple example.


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