EVALUATION OF E-FIELD UNIFORMITY FOR IMMUNITY TESTING IN A REVERBERATION CHAMBER

Testing for immunity against electromagnetic disturbances has become an important aspect of preventing malfunctions in electronic equipment, particularly medical equipment, caused by mobile and other radio transmitters. Radiated immunity tests are generally performed in an anechoic chamber as a standard method [1]. However, reverberation chamber and TEM waveguides, such as a stripline and a TEM-cell, are discussed with IEC and CISPR as an alternative or new testing to conventional measurement, which uses an anechoic chamber [2]-[4]. The reverberation chamber is a shielded enclosure equipped with one or more mechanical stirrers [5]-[8]. The stirrers are used to vary the electromagnetic boundary conditions to obtain a statistically uniform field in the chamber. Therefore, the field in a reverberation chamber, in which the direction of polarization changes randomly by the stirrers, is different from that of an anechoic chamber. Determining the number of stirrer positions and measurement locations for a given test volume in a reverberation chamber is important because they affect the uniformity and field calibration of the test volume. We have experimentally evaluated the effect on field uniformity of the number of stirrers, their positions, and the number of locations measured for the case of a reverberation chamber applied to radiated immunity testing.