The effect of a grounded conductive sheet placed over a PCB with a microstrip line on the electromagnetic noise shielding is discussed experimentally and with FDTD modeling. The grounding position of the sheet, which is connected with the ground plane of PCB, is changed. In results, the resonance frequency is shifted by the grounding position, and reducing the resonance of the input impedance should make a more effective shielding for EM noise radiation below 1 GHz.