Field non-uniformity over the uniform field area as per IEC 61000-4-3 radiated immunity test

The scope here is to quantify the non-uniformity of the electric field over the uniform field area as defined in the IEC 61000-4-3 standard for radiated immunity test. To this purpose the electric field intensity data over the 1.5 m x 1.5 m area, provided by nine laboratories, were collected and analysed. The frequency range considered is between 80 and 1000 MHz. It is shown that the non-uniformity is nearly frequency independent and amounts to 1.2 dB in terms of one standard deviation. This figure is meant to represent the average performance expected from a laboratory complying with the – 0 to + 6 dB field-uniformity requirement of the standard and is offered as a reference value useful for uncertainty evaluations.