A course added to the LearningMeasure.com course catalog in the last year is
In this course the concepts of impedance and admittance are explored. For one-port devices impedances and admittances are complex numbers, but for devices with two or more ports, impedance and admittance are matrices that relate currents and voltages at the device’s ports. Related to these matrices are the ABCD matrix for two-ports, and the scattering matrix or S-parameters. These concepts are all introduced in this course.