Analysis of microwave integrated circuits using the finite element method

A full-wave vector finite element method is implemented in this paper for modeling three-dimensional (3D) unshielded microwave circuits. A two-dimensional (2D) eigenvalue analysis is first applied at the input and output ports to evaluate the dominant field distribution, reference voltage, propagation constant, and characteristic impedance of the corresponding transmission line. The field distribution at the input port is used to excite the 3D circuit. The propagation constant is used in the implementation of first-order absorbing boundary conditions at the two ports, whereas the reference voltage and characteristic impedance are both used in the evaluation of the corresponding S-parameters.