EM-based optimization of a single layer SIW with microstrip transitions using linear output space mapping

A computationally efficient linear output space mapping technique is proposed in this work to optimize single-layer SIW interconnects with microstrip transitions using full-wave electromagnetic simulators. The initial design of the SIW structure is obtained from empirical equations. A very low-resolution EM model with solid walls (grooves) and lossless metals is exploited as an efficient surrogate for direct EM optimization. The surrogate model is enhanced by developing an output linear mapping over a large region of interest, centered at the optimal coarse model solution. The enhanced interpolated surrogate is re-optimized to find the optimal transition. An excellent match is obtained between the original fine model and the enhanced surrogate model at the optimal solution found. The proposed technique is illustrated by designing a 10-50 GHz SIW interconnect with microstrip transitions on a standard FR4-based substrate.