Fast adaptive mode reduction scheme for efficient computation of cascaded filters by the MoL

The method of lines (MoL) with discretization lines in longitudinal direction is a versatile tool for the numerical modeling of cascaded structures. However, the rigorous full wave analysis of complex circuits affords a fine discretization mesh resulting in a large eigenmode spectrum. By employing the concept of localized and accessible modes, the computational complexity of the MoL-algorithm is greatly reduced. A fast adaptive mode reduction scheme is demonstrated for a cascaded planar hairpin filter, where the results of the new algorithm compare well to the conventional MoL approach and to measured results.