Inverse Design Method of Metal Structures in Multiport Waveguide Based on Numerical Green's Function

This article proposes an inverse design method based on numerical Green's function (NGF-IDM) to achieve the intelligent and efficient design of waveguide devices. Inspired by the metal inverse scattering theory, we use the induced current source model to inverse-design metal structures in a waveguide. We divide the design domain by meshing grid points and parameterize the design metal structure and the induced current distribution. Through the numerical method, we extract the numerical Green's function of the multiport waveguide at one time. Different structures will be transformed into different current sources placed in the background waveguide through the least-squares method. Then, under the constraints of physical equations, we achieve the inverse solution from the design target to the metal structure. Case 1 presents an inverse-designed 1-to-3 phase-shifting power divider, proving the method's capability for designing multifunctional electromagnetic devices. Keeping the background waveguide structure unchanged, Case 2 realizes a 1-to-3 frequency divider, illustrating the flexibility of the NGF-IDM. The experimental results show that the theoretical, simulation, and measurement results are highly consistent, proving the feasibility and effectiveness of our method. NGF-IDM enables efficient design in complex environments without iterative full-wave simulations, significantly improving design efficiency. This article provides a new idea for the integrated and highly flexible design of electromagnetic waveguide devices.