Analysis of Emission from Printed Circuit Board with a Conducting Wire Directed to Various Directions

Emission from a printed circuit board (PCB) with a finite size becomes serious when the common mode current is excited on it. Such the common mode current can be occurred at connections of conducting wires, or at a discontinuity of a line or a ground plane on a PCB. In order to clarify a relation between connected a conducting wire to emission, the authors analyzed emission from a PCB connected a conducting wire directed to upper or lower direction at the ground edge using finite difference time domain (FDTD) method. From numerical results, it is shown that in case of a conducting wire connected to upper direction, the radiation power is the largest. Moreover, for the position of a microstrip line, the radiation power is the largest when the distance between the microstrip line and the wire is small. Further, the experimental results of radiation power show the validity of the numerical results.