Improvement in Harmonic Measurements for Military Radiated Immunity Tests

According to updated EMC standards, harmonic levels of radiated immunity test systems must be measured. Several measurement techniques are defined in literature. The MIL-STD-461G RS103 test is one of the important closed-loop radiated immunity tests for military and aerospace equipment. As per MIL-STD-461G, it must be ensured that the field sensor used in the test indicates the field from the fundamental frequency and not from the harmonics. On the other hand, no method is proposed in the standard or in literature to precisely measure or detect the harmonic levels in the presence of the metal surface test table, the ground floor and even the Equipment Under Test (EUT) in a closed-loop test. In this paper, we propose a very efficient way to measure the undesired harmonics produced by the amplifier and antenna during an actual closed-loop military immunity test in the presence of the test setup and EUT.