In analog transmission technology, a quadripole is a functional unit with a two-pole input and a two-pole output. The function of the quadripole is adequately described by the transmission behavior or the quadripole parameters.
The main characteristics of quadripoles include the attenuation or gain, phase response, group delay, and input imp edance and output impedance. As for the quadripole parameters, we are talking about the matrices for impedance, known as Z-parameters, admittance with theY-parameters, scattering parameters(S-parameters), as well as the forward and reverse hybrid matrix parameters, H-parameters and G-parameters.
A quadripole can be a cable, an attenuator, filter, resonant circuit or oscillator, an amplifier, transmitter, or a complex analog circuit with a wide variety of functions. In digital technology, the quadripole is sufficiently defined by its internal logic.