Capacitance of an annular ring between two conducting plates

In this article we propose a general method for estimating the capacitance of a ring placed between two dielectric layers, externally grounded. This g eometry is relevant in microstrip design and testing. The problem, formulat ed as three integral equations defined in complementary regions, is solved by adopting a generalised Neumann series, whose general term is the product of two Bessel functions. Plots of the capacitance are given in a wide rang e of geometric and electric parameters.