s2abcd

Convert S-parameters to ABCD-parameters

Syntax

abcd_params = s2abcd(s_params,z0)

Description

abcd_params = s2abcd(s_params,z0)converts the scattering parameters to the ABCD-parameters.

Examples

Convert S-Parameters to ABCD-Parameters

Define a matrix of S-parameters.

s_11 = 0.61*exp(j*165/180*pi);
s_21 = 3.72*exp(j*59/180*pi);
s_12 = 0.05*exp(j*42/180*pi);
s_22 = 0.45*exp(j*(-48/180)*pi);
s_params = [s_11 s_12; s_21 s_22];
z0 = 50;

Convert S-parameters to ABCD-parameters.

abcd_params = s2abcd(s_params,z0)

abcd_params = 2×2 complex

   0.0633 + 0.0069i   1.4958 - 3.9839i
   0.0022 - 0.0024i   0.0732 - 0.2664i

Input Arguments

s_params — 2N-port S-Parameters

2N-by-2N-by-M array of complex numbers

2N-port S-parameters, specified as a 2N-by-2N-by-M array of complex numbers, where M represents the number of frequency points of 2N-port S-Parameters.

z0 — Reference impedance

50 (default) | positive real scalar | positive real vector

Reference impedance in ohms, specified as one of the following:

• Positive real scalar when you want to specify the same the reference impedance for all ports in the network.

• Positive real vector of length N when you want to specify a different reference impedance for each port in the N-port network. (since R2023a)

• Positive real vector of length K when you want to specify a different reference impedance for each in the K frequencies in the data. (since R2023a)

If the reference impedance is a vector and the number of ports N equals the number of data frequencies K, N == K, then the sparameters object will assign each element of the vector to each port of the network. To specify reference impedances for each frequency in this case, specify Z0 as a 3-D vector of length 1-by-1-by-K.

Output Arguments

abcd_params — 2N-port ABCD parameters

2N-by-2N-by-M array of complex numbers

2N-port ABCD parameters, returned as a complex 2N-by-2N-by-M array, where M represents the number of frequency points of 2N-port ABCD-parameters. The output ABCD-parameters matrices have distinct A, B, C, and D submatrices:

$$\left[\begin{array}{cc}[A]& [B]\\ [C]& [D]\end{array}\right]$$

References

[1] Pozar, David M. Microwave Engineering. 3rd ed, J. Wiley, 2005.

Version History

Introduced before R2006a

R2023a: Specify multiple reference impedance values

Specify a different reference impedance for each port in the network by setting the z0 argument to a vector.