Resonance frequency variation with a nearby floated metal plate

It is not rare case that a floated metal plate exists nearby high speed cir cuit traces. Heatsink placed on a IC chip nearby circuit traces, metal encl osure or circuit traces in a compact designed product may be a good example . It may be also seen such structure for a shield hox and circuit traces co nfined. It is generally known that such metal plate as plating nearby circu it trace may change circuit trace parameters and then resonance frequency a ssociated with the circuit trace. In this study, we clarified resonance fre quency variation with comprehensive observation of input impedance of micro strip line that is an essential model of circuit traces on a printed circui t board. Since such structure is created in various cases in product design s, we believe that the results shown in this study may he useful for EMC de sign as well as signal integrity. For computation, method of moment was use d.