Study on the Characteristics of S21 and EMI on a Shifted Electromagnetic Band Gap (EBG) Structure

AI-EBGs attenuate the through characteristics with broad bands of high frequency. AI-EBGs have structures in which sections of low characteristic impedance and high characteristic impedance are arranged periodically. However, the characteristics of radiated EMI of AI-EBGs are not well known. In this study, the characteristics of S₂₁ and EMI are examined when the patch and the branch sizes are varied while the size of the printed circuit board and the number of patches are kept constant. In addition, the characteristics of S₂₁ and EMI are examined when the dielectric thickness is varied. An AI-EBG structure with a thin dielectric is found to give the optimal S₂₁ and EMI characteristics. Finally, a shifted EBG structure is proposed.