atlc is an Arbitrary Transmission Line Calculator (for transmission lines and directional couplers).

There are 12 programs that comprise the package atlc. One of the programs is called atlc; the other 11 have different names. Using the programs comprising the package atlc one is able to:

-Calculate the characteristic impedance and other properties of two conductor transmission lines, like coaxial cable (far left above), but the cross section can be of any shape whatsoever, including that second from the left. A technique known as finite difference is used for this.

There can be an arbitrary number of different dielectrics. The inner conductor is shown red, the outer green and a vacuum dielectric is shown as white - for all practical purposes, the permittivity of a vacuum (1.0 by definition) dielectric is the same as that of air (approximately 1.0006)

-Calculate the impedance's for both the odd-mode and even-mode, along with many other properties of directional couplers of arbitrary cross section, like that third from the left below. Note, with couplers, there is two inner conductors, with - one red as before, but another one blue, in addition to the green outer conductor. The finite difference technique is used for this too. Analysis extends to couplers with multiple dielectrics, such as the microstrip coupler on the PCB on the right below.

-Compute the common-mode impedance Zcomm and differential-mode impdance Zdiff of arbitrary directional couplers.

-Compute the values of electric field, voltage, energy stored etc in 2 and 3 conductor transmission lines and save this data to binary files, as well as bitmaps which can be viewed in a graphics package.

-Automatically create bitmaps for some common transmission lines, to save the user having to create them in a graphics package, which would soon become tedious.

-Compute the odd and even mode impedances required of an arbitrary directional coupler to satisfy a given frequency response and coupling factor.

-In the case of a coupled stripline with thin conductors, the program design_coupler can fairly quickly (within a few minutes) compute the dimensions of a directional coupler to satisfy your requirements of frequency response, coupling factor and optionally length.

If you wish to implement the design on a double-sided printed circuit board like that on the right below, the program find_optimal_dimensions_for_microstrip_coupler will do this for you, but it takes several hours (perhaps a couple of days) to find a solution, although some well-timed and sensible human intervention can reduce this considerably.

-Since the program atlc can save quantitative data on the x and y components of electric field, energy, voltage etc to binary files, there is a program readbin that can read the binary files and tell you something about the data saved in them.

This information is for debugging only - it is not expected the user will use readbin. The user is expected to write their own programs to read this binary information, in the very unlikely event they wish to use the information. It is likely to be of academic interest only. The normal output from atlc is in simply text.