“…Computational speedup can be obtained using surrogate-assisted techniques [7,43,44], where the optimization burden is shifted into the cheaper representation of the structure of interest. In some situations, typically for simple components, development of analytical models is possible [45,46], in others (particularly for structures such as microwave filters, couplers or power splitters), equivalent circuit models can be used [1], [30]. Both types of models are very fast.…”