When calculating the proper resistance of the basis function we must take into account the input resistance of the corresponding receiving module

(10а) |

(10б) |

Elements of the free term column in (8) are defined by the incident wave field and can be calculated as follows:

— extraneous field: *H*-wave (*Е*-polarization)

(11) |

— extraneous field: *E*-wave (*H*-polarization)

(12) |

where *F _{ip}* is defined as follows:

(13) |

Solution of the system (8) defines amplitudes of the basis functions of the currents for the given excitation. When calculating the scattered field, the depolarization of the incident *E* or *H*-wave is taken into account. To do it, we consider excitation of the structure by a combination of two plane homogenous waves, with one of them being *E*-wave and the other being *H*-wave. Let both waves propagate in the negative direction of the *Z* axis by angles *θ* и *φ*, and the intensity of the electric field modulo for both waves is equal to 1. Then the transversal components of vectors of these waves are defined by expressions (1) and (2). By solving the diffraction problem separately for each type of wave we get the values for transverse components of the back-scattered field in the far-field region

(14) |

In both these cases the full back-scattered field will be related to the incident wave by the fol-lowing relations:

(15) |

where *S* is the scattering matrix, which characterizes the reflective properties of the structure. Since, after solving the diffraction problem we know the left parts of the expressions (15), they can be considered equations relative to the elements of the *S* matrix

(16) |

By transposing the matrix in the system (16) we get the following expressions for the elements of the matrix [*S*]:

(17) |