Comments on "Upper Bound Calculations on Capacitance of Microstrip Line using Variational Method and Spectral Domain Approach"

The author read with interest the above paper in whkh an analytical approach based on the Fourier transformation and variational techniques have been employed; the surface potentiaf V(x) of the dielectric sheet in order to find the upper bound of the microstrip line capacitance C has been used. Thus this approach complements that of Yamashita et al, who calculated the lower bound C/sup L) dealing with the charge density Q(x) on the surface of the conductor strip; consequently, the margins of error in the variational calculation can be estimated.