Atlc is a finite difference programme that is used to calculate the properties of a two-conductor electrical transmission line of arbitrary cross section. It is used whenever there are no analytical formula known, yet you still require an answer. It can calculate: The impedance Zo (in Ohms) The capacitance per unit length (pF/m) The inductance per unit length (nF/m) The velocity of propagation v (m/s) The velocity factor, v/c, which is dimensionless. A bitmap file (usually with the extension .bmp or .BMP) of the cross section of the transmission line is drawn in a graphics package such as The Gimp and then analyzed using Atlc.