New Approach to Fast Full Wave Optimization of Microwave Filters

The gradient based optimization technique along with a new definition of a cost function is applied to the direct electromagnetic CAD of coupled resonators filters. The topology of the structure is enforced on each step of optimization and the cost function is defined using location of zeros and poles of the filter´s transfer function. With the new objective function the optimization process converges to the desired solution from an arbitrary selected initial point (provided the assumed topology permits it). Moreover, the new objective function is constructed form numerical processing of scattering matrix parameters computed at a very few frequency points. As a result the optimization is fast and very good filter designs can be obtained in short time without any need of microwave synthesis.