Terms pertaining to S-Parameters:
Magnitude (MAG): The length of the vector in the polar plane. Also expressible in dB as 10log(MAG).
Angle (ANG): The direction (or phase angle) of the vector in the polar plane.
Characteristic impedance (Zo): The system characteristic impedance (typically 50 ohms) to which the measurements are referenced.
S11: Expresses the magnitude and phase of the input reflection coefficient, measured with the input and output ports terminated in Zo.
S21: Expresses the forward gain magnitude and phase, measured with the input and output ports terminated in Zo.
S12: Expresses the reverse gain (sometimes called isolation) magnitude and phase, measured with the input and output ports terminated in Zo.
S22: Expresses the magnitude and phase of the output reflection coefficient, measured with the input and output ports terminated in Zo.
