Scattering parameters describe the electrical behaviour of linear electrical networks under the influence of electrical signals. These are useful for designing the electrical, electronic and communication systems. Although applicable at any frequency, the s-parameters are mostly used for networks operating at UHF and above, including the microwaves where signal power and energy considerations are more easily quantified than currents and voltages. As these parameters change with the frequency, the frequency needs to be specified for any stated s-parameter measurement, in addition to the characteristic impedance or system impedance. The scattering parameters are readily represented in matrix form and thus are the elements of a scatter-
At microwave range, the wavelengths of the signals are dismally small and the dimensions of the components are drastically reduced. While propagating through such components or combination thereof, even a microscopic aberration in the surface of any device or mismatch at joints in the passage is seen by the wave as an obstacle. The unevenness and mismatch, bends, corners, twists and so on may (often) result in undesirable phenomena of reflection or scattering of energy. The s-parameters that represent the reflection coefficient of a port and transmission coefficients between different ports, when other ports are matched terminated, can account for any such discrepancy. As incident and reflected waves contain phases and amplitudes, s-parameters, which are closely related to these, they are complex quantities.