DETERMINATION OF CIRCULAR MICROSTRIP DISK BY NOBLES VARIATIONAL METHOD

Noble's variational method is applied to the calculation of the static capacitance of a circular microstrip disk by using a linear combination of two types of charge distributions, namely, a uniform charge distribution, or gate function, and the classical form of the charge distribution for the infinitely thick slab, or Maxwell's function. The variational method reduces the dual equations describing the microstrip problem to the evaluation of three similar integrals, which can then be evaluated efficiently and accurately by the Gauss-Laguerre quadrature. It is found, as a rule, that the method gives a more accurate representation of the charge distributions on the disk, yields values of capacitance which are within better than 0. 4% of the values obtained from a numerically accurate method and is capable of being implemented on a programmable calculator, e. g. the HP-41 C.