Effect on electromagnetic radiation by conductive plane placed near a PCB

The suppression and/or radiation effects of electromagnetic noise with a conductive plane shielding near a PCB with a microstrip line are discussed. The distance d between the PCB and the conductive plane, the plane size, and the grounding position on the plane are varied. The magnetic near-field is measured by a shielded-loop probe. The input impedance is also measured, and calculated by the FDTD method. In results, the distance d /spl ges/ 8 mm is more suitable to reduce the effect of the electromagnetic coupling, and changing the conductive plane size and the grounding position change the shielding effect on the magnetic field.