# skrf.network.Network.s_active¶

Network.s_active(a)[source]

Returns the active s-parameters of the network for a defined wave excitation a.

The active s-parameter at a port is the reflection coefficients when other ports are excited. It is an important quantity for active phased array antennas.

Active s-parameters are defined by [1]:

$\mathrm{active(s)}_{m} = \sum_{i=1}^N s_{mi}\frac{a_i}{a_m}$

where $$s$$ are the scattering parameters and $$N$$ the number of ports

Parameters: a (complex array of shape (n_ports)) – forward wave complex amplitude (pseudowave formulation [2]) s_act – active S-parameters for the excitation a complex array of shape (n_freqs, n_ports)

See also

z_active()
active Z-parameters
y_active()
active Y-parameters
vswr_active()
active VSWR

References

 [1] Pozar, IEEE Trans. Antennas Propag. 42, 1176 (1994).
 [2] Williams, IEEE Microw. Mag. 14, 38 (2013).