This study presents wideband analytical Green's functions of microstrip structures using a two‐dimensional (2D) complex images method. The unknown coefficients of exponential terms are obtained using different particle swarm optimisation (PSO) algorithms such standard PSO, meta PSO, binary PSO, quantum PSO (QPSO) and ramped convergence PSO (RCPSO). The simulation results of both the magnetic vector and electric scalar potentials obtained by the PSO methods are compared and discussed. It is shown that the QPSO and RCPSO methods give considerably better solutions to the problem compared with other PSO algorithms. Then, a hybrid QPSO‐gradient‐based technique is used to improve the precision of the 2D complex images. The closed‐form Green's functions are valid over a wide range of frequencies and regions. The numerical results show close agreement with the rigorous numerical integration of Sommerfeld integrals.

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