Rapid Microwave Optimization Using a Design Database and Inverse/Forward Metamodels

Electromagnetic (EM)-driven parameter tuning plays an ever-increasing role in contemporary microwave design. The primary reason is the growing complexity of circuits and the lack of simpler (analytical, network-equivalent) models capable of accounting for effects such as EM cross-couplings within miniaturized microstrip components. The high CPU cost of EM-based optimization can be alleviated in various ways, one being utilization of already existing designs obtained for various sets of performance specifications. This paper proposes a practical procedure that greatly accelerates parameter tuning by exploiting the information contained in the existing design database. The latter is encoded into an inverse kriging metamodel utilized to yield a good starting point and a forward surrogate providing an initial estimate of a Jacobian matrix of the system response. Our methodology is illustrated using a miniaturized three-section impedance matching transformer with its operating bandwidth edges re-designed from 1.5 GHz to 3.5 GHz (lower end) and 4.5 GHz to 6.5 GHz (upper end).