Analysis of the Electromagnetic Interaction Between Periodically Corrugated Transmission Lines Through the Mutual Capacitance and Mutual Inductance

In this study, we established, for the first time, an equivalent circuit model for coupled subwavelength periodic microstrip lines (CSPMLs) over a wide frequency range. The circuit composed of two identical and parallel subwavelength periodic microstrip lines has two fundamental modes, i.e., odd and even modes. Based on the two fundamental modes, the finite element method (FEM) is used to extract the circuit parameters, especially the frequency-dependent behavior of the mutual capacitance and mutual inductance for the CSPMLs. The S-parameters evaluated by full-wave simulation and the circuit model were highly consistent with a maximum deviation of only 0.249 dB for transmission coefficient below 15GHz. Because of reduced the mutual capacitance and mutual inductance, the crosstalk between two adjacent microstrip lines could be suppressed by optimizing the subwavelength periodic structure. The measured characteristic impedances for differential and common signals of CSPMLs also agree well with the numerical results. Therefore, we expect that the application of circuit models of CSPMLs would accelerate the use of metamaterial technology in the existing high-speed circuit systems.