Approximate Coupling Formulas for the Coupling Between Microstrip Resonator Antennas

Generally the best-known methods for computing mutual impedances are based on a direct integration of the Ē and H fields, as given in Jordan [1]. Other methods involve approximations valid for large, in theory infinite arrays, reducing any integration in the spectral domain to mere summations [2]. Some derivations have been made by array specialists coming to the solution for identical slots in both the electric and magnetic wall formalism [3]. This theory will be extended here, and applied for the case of rectangular microstrip antennas. So simple formulas that can be used both for analysis and synthesis will be found by asymptotic approximations of the integrals found.