Quasi-static Analysis of a Coplanar Strip Line with Shielding Planes Used as a Distributed Sensor

A calculation of the primary parameters of coplanar strip lines placed between two shielding planes is presented. The line cross sections contain a dielectric material non-uniformly distributed over the layers. The analysis problem is solved in a quasi-static approximation by the conformal mapping and numerical grid methods. Analytical expressions are derived for calculating the unit-length capacitance, effective dielectric constant, and characteristic impedance. An example of application of such lines as a distributed sensor is given. The property of slight dependence of the electric field in the lower dielectric layer of the coplanar line under study on the electric field in its upper part is used. This property is observed in the case of narrow gaps between the current-carrying strip and the side planar screens. A linear dependence of the per-unit-length capacitance and the effective dielectric constant of the coplanar strip line on the dielectric constant of the upper dielectric layer is obtained. Other applications of this strip structure are shown.