A comparison of bulk cable current injection and radiated field susceptibility test methods

Bulk cable current injection of modulated RF signals will be included in MIL-STD-461D and MIL-STD-462A as conducted susceptibility Test Method CS114. Test Method CS114 is designed to evaluate the susceptibility of electronic equipment to RF signals coupled into the equipment through the cabling. The author presents an examination of cable current produced by bulk cable current injection (BCCI) and by a radiated field for two cases: a simple multiwire cable mounted above a ground plane with each wire terminated with resistors at both ends, and an operational radar altimeter system mounted on a mockup of an aircraft instrument panel. For the simple multiwire test case, the bulk cable current induced on the cable by a current injection probe and by a radiated field is examined for two cable shield termination configuraions and two wire termination resistances. The radar altimeter, with a known cable-coupled digital altitude susceptibility, is evaluated for several cable shield termination configurations. BCCI testing tends to produce a more significant standing wave on the test cable than radiated field testing. Radiated field testing produces greater variation in the per wire current than BCCI testing. BCCI testing is an effective technique for evaluating system susceptibilities caused by electromagnetic-interference coupling into the system through the cabling