Investigation on the Interplay Between S Parameters and Near-Field Radiation Characteristics of Defected Ground Structures

Defected Ground Structures (DGSs) are widely used to improve the electric and electromagnetic characteristics of devices and components, which may affect the signal transmission performance and lead to radiation emissions at specific frequencies. In this work, the relationship between near-field radiation and S parameters of the signal transmission channels with DGSs was revealed using theoretical modeling and experimental tests. Based on the S parameters results, the Seq parameter was derived and calculated. The results indicate that the peak near-field electric radiation intensities occur at frequencies of peak Seq values. A three-dimensional (3-D) electromagnetic field model and an equivalent circuit model were developed to analyze the S parameters and near-field electric radiation intensity. High-frequency and near-field measurements were both conducted to verify the simulation results. This study provides a theoretical support for predicting frequencies corresponding to peak radiation intensities of DGSs via S parameters, which are essential for mitigating electromagnetic compatibility (EMC) issues in electronic systems.