The Hybrid-Mode Analysis of Coupled Microstrip-Slot Resonators (Comments)

We were interested to read the above paper, but it calls for a remark concerning the extension of the hybrid-mode analysis to coupled microstrip-slot resonator. In fact, when the coupled strips are very close to each other, the basis functions used in the above paper does not allow one to obtain a satisfactory resonant frequency. To do so, we must necessary increase the number of basis function by using symmetric and antisymmetric basis functions with respect to the axis of a strip. In this case, we must be sure that the criterion of relative convergence is satisfied. Furthermore, the mathematical developments of this hybrid-mode analysis have been already published by the same author. So it would have been better to focus the purpose of the above paper on the problem more specific to the coupling of the two strips.