Effect of ground guard fence with via and ground slot on radiated emission in multi-layer digital printed circuit board

In high-speed digital printed circuit board (PCB), the ground guard fence is often used to reduce the radiated emission and the crosstalk. Moreover, it is quite useful for the presence of the ground slot under the signal trace to avoid the reflection and the radiated emission. In this paper, the effects of the guard fence are studied by experimental measurement and numerical electromagnetic simulation. It is found that the ground guard fence acts efficiently as the shielding wall against the signal trace, which results in the significant reduction of the radiated emission. Also, its inherent low radiation property works well at presence of the ground slot under the signal trace.