A new method for the calculation of the equivalent inductances of coplanar waveguide discontinuities

Capacitive and inductive model parameters of coplanar waveguide discontinuities are calculated using the quasi-state three-dimensional finite difference method. The equivalent inductances are derived from the magnetic field distribution in the coplanar slots which is determined by solving the Laplacian equation for the inverse structure (i.e., replacing the conductors with slots and vice versa). The method is applied to coplanar air bridge T-junctions and the results are compared with measurements. The influence of different types of air bridges is also investigated. The biggest advantage of the proposed method is its small computation time (20-30 seconds for the presented junctions) and its relatively small memory storage requirement as a result of the nonequidistant discretization and the use of the iterative overrelaxation method.<>