Comparison of Power Measured by the MDS Clamp and Electric Field of the Interference

This paper discusses the correlation between the measured values, using the interference power measuring method with the MDS clamp specified in CISPR Publ.2, and the electric field measurement with a dipole antenna. The electric fields were measured for three cases concerning the disposition of the mains lead. The first was one which is specified in CISPR Pub1.2; the mains lead being wrapped around the reel. The second was the same as the MDS clamp method; the mains lead being stretched in a straight line about 5 meters long. The third was the same as the second one but the MDS clamp was put on the mains lead and the position of the clamp was moved to get the maximum reading of the field. By these measurements, the following results were obtained. (1) When the mains lead was wrapped around the reel as specified in CISPR Publ.2, radiation was very weak in comparison with the calculated value by the equation $\mathrm{E}=7\sqrt{\mathrm{p}}/\mathrm{d}$ (P: power, E: electric field, d:measuring distance). (2) The measured maximum electric field of interderence was less than the calculated value by about 10 dB or more.