Spectral Domain Analysis of an Elliptical Microstrip Ring Resonator (Comments)

Along with the above paper several other papers have been published recently by Sharma and his co-workers [2]-[3] on the analysis of the resonant frequencies of a microstnp disk using the quasi-static approach. The quasi-static approach has been proven to be incorrect in [4] and [5]. The quasi-static argument on the correction to the resonant frequencies of a microstrip disk is based on some intuitive arguments that are not rigorous. The only thing it predicts correctly is that the resonant frequencies of a microstrip disk should decrease compared to that of a magnetic-wall model. The author may argue that since the correction to the magnetic-wall model is small, any approximate method is viable. However, we have found that the quasi-static correction could be as much as 50 percent in error. Even when this correction is small, if we bother to caIculate it, I think we should calculate it correctly. The author´s quasi-static correction has a new twist compared to earlier authors, but when epsilon_r = 1, it does not differ from the quasi-static correction of earlier work.