Verification of the HERO Requirements of an Explosive System with Reference to the MIL-STD 464A (HERO testing).

In this paper the results of a HERO measurements campaign on an ordnance system are reported, together with additional considerations regarding the use of a reverberation chamber as suggested in the recently issued MIL-STD 464A standard [1] and in the related MIL-HDBK 240 [2]. The investigation phase for resonance conditions was performed using a GTEM cell in the frequency band 10 KHz-1 GHz, and a reverberation chamber starting from 1 GHz up to 18 GHz; to reduce the test duration, the number of test frequencies was limited to the minimum requested by the standard. A resonance was found around f=1.783 GHz, therefore a second phase of the test was performed in an anechoic chamber in the reduced frequency range 1.543-2 GHz, with the result to identify the “true” more hazardous frequency of 1.863 GHz. In conclusion, the use of a reverberation chamber allows to perform the preliminary investigation for resonance conditions in shorter time - without to repeat the test twice for both field polarizations, as the standard would require - and with lower power to obtain the required test levels Moreover, the Authors think that improving the performance of reverberation chamber below the LUF (Lowest Usable Frequency) could make it more competitive in generating the test fields, and perhaps could allow to investigate for resonance conditions using only the reverberation chamber for the complete frequency range.