Bulk Current Injection as an Alternative Radiated Susceptibility Test Enforcing a Statistically Quantified Overtesting Margin

Abstract

Experimental results are presented in support of the use of bulk current injection (BCI) as an alternative technique to unit-level radiated susceptibility (RS) verifications up to 1 GHz. The rationale for the correlation of BCI/RS test levels is grounded in the concept of overtesting (OT), which quantifies the excess of disturbances injected by BCI with respect to RS. Previous works showed that OT is a random variable, owing to unknown and uncontrolled setup parameters including the common-mode impedance of the equipment under test. The cumulative distribution function (cdf) of OT was shown to be predictable, by means of reasonable statistical assumptions and simple circuit models. This paper fills the gap between that simplified theoretical analysis and the complexity of real-world test setups. To this aim, an ad hoc structure mimicking typical wiring harness and equipment for aerospace applications is tested with BCI and RS to collect several results in terms of power injected/induced in the terminal units. The obtained datasets are processed to infer the empirical cdf of OT. Results are compared with theoretical predictions and properly discussed to point out the correlation between BCI and RS achieved in different test cases (vertical/horizontal antenna polarization, unshielded/shielded cables).