The measurement method of EM field inside box

This paper presents the way of measuring EM field inside metal box using loop and monopole sensor. The rectangular box which has two rooms and two apertures was placed in four-wire TEMcell. EM field can penetrate the shield through apertures and cables. Penetrated EM field into box was investigated. Knowledge of EM field inside box is useful information to determining areas of high current concentration which may cause chip or circuit to malfunction. It is possible to find out selectively dominant frequencies which exist and influence circuits inside box. The calibration method was used to obtain accurate EM field measurement. To calibrate the measurement of surface current, theoretical surface current of the sphere computed from the Mie series was used. And the measured results were compared to the simulation results.