Ultra-fast finite element simulation of planar electromagnetic structures

Microwave devices and antennas often form layered structures consisting of multiple dielectric and metallization layers with the metallization interconnected by vias. The paper employs a mode decomposition approach to modeling such structures that greatly reduces simulation requirements. We decompose the fields in planar structures into two types of modes: (1) parallel plate cavity modes in which the electric field is assumed to be purely normal to the power and ground planes in the structure; (2) TEM modes for propagation in the direction of the metallization traces between the power and ground planes. The finite element method is used to obtain a solution for both modes. The computations are very fast and usually take only seconds. Electromagnetic models of vias are used to tie the two types of modes together. The procedure has been used to simulate a wide variety of planar electromagnetic components. A simple test example is presented. Examples involving many layers and complex metallization patterns with thousands of traces are solved accurately orders of magnitude faster than would be possible with full three-dimensional finite element solvers.