Computation of mutual coupling between slot-coupled microstrip patches in a finite array

An analytical method is presented for the evaluation of mutual coupling between slot-coupled microstrip patches in a finite array. The approach is a combination of the equivalence principle and the reciprocity theorem and uses the spectral domain Green´s functions for a dielectric slab in a moment method solution for the unknown patch and slot current distribution. The excitation mechanism of the patches is taken into account by introducing an N-port equivalent network, and the impedance matrix of an array of N-element slot-coupled patches is evaluated directly from its network voltage and current matrices of order N². As examples, the mutual impedances and scattering coefficients for two-, four-, and eight-element arrays are evaluated. Results are compared with measured data