Читать книгу Introduction To Modern Planar Transmission Lines - Anand K. Verma - Страница 126

The true S‐parameters of the line section, i.e. its de‐embedded S‐parameters over a range of frequencies are known either through the measurement or through the EM‐simulation. This information can be converted to the [ABCD] parameters of a line section as follows [B.1]:

(3.2.23)

Usually, S₁₁ = S₂₂ and S₁₂ = S₂₁ because a section of the transmission line is treated as the symmetrical and reciprocal network. The frequency‐dependent [ABCD] parameters of a lossy line of length ℓ are used to compute the characteristic impedance Z₀ and propagation constant γ = α + j β over a range of frequencies [B.1]:

(3.2.24)

The frequency‐dependent secondary line parameters are extracted to get the dispersion characteristics of a line. Once the secondary line parameters of a line section are known, their frequency‐dependent primary constants are computed as follows:

(3.2.25)