“…The characteristic equation for calculating y, , for an array of NP dielectric slabs per cell was later obtained [8,11,12] and given by where MPii are elements of an M, matrix, resulting from the product of the transmission matrices of each Lth dielectric slab. This matrix is obtained by applying the boundaly conditions, at the interfaces between slabs e and e+ 1, on the fie'3 colALponents transverse to the x axis, propagating along this axis, in each one of the Lth slab, with a phase constant given by and expressed by [ll, 121 (10) is the admittance of each mode propagating along the x direction, equal to ( m , E r i ) / k i n or kin/Wpo for the 'I'M or TE modes, respectively, and u,, = k,,d, is the phase constant, normalized with respect to the dielectric slab thickness. After obtaining the values of y, , from eq.…”