EMC testing on airborne equipment

Electrical and electronic equipment often (unexpectedly) produce Radio Frequency (RF) energy. Every digital/analog device has the potential of causing unintentional interference to other electrical devices. Communication and radar systems rank highest in the areas of concern when interference from unintentional sources of RF energy would be observed. The impetus to EMC in avionics arose from the US Air Force concerns due to the problems caused by the Distant Early Warning (DEW) line Radar. Even though analog devices are more susceptible to EMI/EMC, still EMC became a wider concern with the development of digital logic devices. Digital devices on one hand had revolutionized the avionics on the other hand it is becoming demanding to control EMI aspects due to high density of components in microelectronics and their high sensitivity make them susceptible to EMI and EMC. With the increasing trend of receiver sensitivity, the EMC compliance is becoming more and more difficult. It is well recognized that EMI/EMC aspects must be taken care of right from the beginning in the design of the circuits, including PCBs and packaging of equipment and systems. The endurance of the paper is to briefly discuss various aspects of EMC testing, instrumentations and test set-ups for airborne applications in ensuring better compliance. The paper briefly covers Nature of interference, Overview of product testing, Validation of measured data, Problems encountered during Emission testing, EMC testing methodologies, Instrumentation, Test facilities and support equipment, Conducting testing, Radiated testing and EMC problems associated with production. The challenges faced in integrating new technologies with the existing one as part of avionics upgrades on military aircraft also have been discussed in the paper.