A Field-Circuit Co-Simulation Method for Antenna and RF Front-Ends with DGTD Solver

Due to the complex structure of array antenna and nonlinear microwave circuit system, the co-simulation of antenna structure and back-end microwave circuit will have multi-scale problems, which greatly affects the simulation efficiency. To solve the above problem, an antenna equivalent model extraction method based on the electromagnetic pulse effect is proposed in this paper first. When the load port of antenna is open, open circuit voltage can be obtained at the antenna receiving port. When the load port is short-circuited, the short-circuit current can also be obtained at the antenna receiving port. According to Davinan's theorem, the complex antenna structure is equivalent to a circuit in series between the signal source and the equivalent impedance. By using fitting function to approximate the resistance curve of antenna in frequency domain, all parameters of fitting function can be solved, and then the expression of impedance function can be obtained. The high-order fitting function in the frequency domain is transformed into the time domain by inverse Fourier transform, and the time domain partial differential equation is discretized by the forward difference method to solve the current density at the antenna port. The next step is to get the current density of the IC (integrated circuit) ports. In this step, the integrated circuit port current can be solved by using the voltage-current relationship such as equivalent lumped-charge model and Ohm's law. Finally, the current density information of antenna port and integrated circuit ports is introduced into Maxwell equation tested by DGTD (discontinuous Galerkin time domain) method through the continuity condition of the field to form a field-circuit co-simulation format. Then several examples of RF field-circuit co-simulation including antenna model can be further proved that the proposed method simplifies the simulation process and the simulation results consistent with commercial simulation software, which shows the effectiveness and accuracy of the proposed method. The method proposed in this paper will provide a convenient way for the co-simulation of complex models.