A Low-loss Transition for Substrate Integrated Coaxial Line to Grounded Coplanar Waveguide Based on Bayesian Optimization Approach

Abstract

In this paper, a low-loss transition between substrate integrated coaxial line (SICL) and grounded coplanar waveguide (GCPW) is proposed, which is designed based on Bayesian optimization (BO) approach. The proposed transition contains stepped vias with different dimensions and grounded vias surrounding the stepped vias, which can reduce the discontinuities between the SICL and the GCPW. To optimize the proposed transition, a BO-based approach is applied. The objective function is set as the return loss of the proposed transition. The Gaussian process (GP) model is used as the probabilistic surrogate model of the objective function. The Probability of Improvement (PI) is selected as the acquisition function. The proposed transition is designed and simulated based on the Printed Circuit Board (PCB) process. The simulation results show that the return loss is larger than 20 dB and the insertion loss is lower than 0.25 dB from Dc to 50 GHz. In addition, compared with the parametric sweep method, the iteration times of the BO approach can be reduced by approximately 90.3%.