A study on suppression of induced voltage on printed wire by external electromagnetic field

One of the most effective ways to prevent malfunctions in electronic apparatus caused by external electromagnetic waves is to develop techniques that effectively suppress the voltage in printed wiring boards caused by these waves. In this paper, the differences in suppression effect that component insertion positions have was discussed when impedance component such as ferrite beads are used. The electromagnetic simulation was used to determine the distribution of voltage and current induced in the wiring when a printed wiring board was placed in an external electromagnetic field, and the relationship between impedance component insertion position and suppression effect was studied by simulation and experiment. Simulation results showed that the impedance component produced the greatest suppression effect at a position one quarter of a wavelength away from the end of a line at which the induced voltage is measured, and experiments confirmed the evidence. Also, suppression effect of resister and chip ferrite beads was compared and it was found that the effect of ferrite beads can be estimated from the impedance value