Efficient calculation technique for the impedance matrix equation in the MPIE technique for microstrip and slotline planar structures of arbitrary shape

A mixed-potential integral equation (MPIE) technique is used to simulate the circuit parameters of arbitrary shaped microstrip and slotline circuits embedded in a multilayered medium. The well-known rooftop functions defined over a mixed grid of rectangular and triangular cells are used to model the electric and magnetic currents on the microstrip and slot circuits. Galerkin´s method is applied to reduce the integral equation to a linear system of equations Z.I = V. Special approximations of the Green´s functions make the analytical calculation of the cell-cell interactions possible. An efficient calculation technique for the elements of the impedance matrix Z is presented. Simulation results for a microstrip bandpass filter and a microstrip-slot coupler are presented.<>