Stationary expressions for scattering coefficients of rectangular waveguides with dielectric plugs constituting a finite planar array

The stationary expressions for the scattering coefficients are given for a finite planar waveguide array (FPWA) with dielectric plugs whose dielectric constants and lengths are arbitrary. The scattering coefficients defined at the air-dielectric interfaces in the waveguides are expressed in terms of the aperture electric fields only and evaluated from the ratio of two determinants. This method is useful for analyzing the mutual coupling effects in FPWA.