プリント回路基板上のコモンモード電流を用いた遠方電界強度の予測

抄録

A far-field prediction from the common-mode current on the traces of printed circuit boards (PCBs) was investigated, which had partly been examined by Paul in the frequency range up to 200 MHz for electrically short traces on the PCB with a narrow bandwidth signal source. Two sample PCBs were prepared, which have two different lengths of balanced parallel traces that are not always electrically short. A battery powered signal generator excited each PCB so that we could expand the frequency range up to 1 GHz with sinusoidal waves. A surface current probe consisting of thin wires wounded on the middle of half-cut ferrite core was used to measure the trace currents. Calculated electric far-field strength based on the common-mode current was compared with the measured far-field strength at a distance of 3m for the above sample PCBs in the frequency range from 30 MHz to 1 GHz. Good agreement between the common-mode current predictions and the measurements was obtained.