Analysis of electromagnetic noise suppression in microstrip lines with absorber sheets

Application of an absorber sheet on printed circuit boards is one of the solutions for improving an electromagnetic compatibility of high-frequency systems. We set to analyze the effect of the absorber sheet on S11 and S12 parameters of a simple microstrip line. We analyzed dependence of the return loss and the insertion loss on absorber sheet thickness and type of material. In addition, we examined also the effect of covering geometry and the effect of absorber sheet covers on thru-hole connections. With this we discuss the best measurement geometry for relevant characterization of absorbers sheets with microstrip set-up.