New method for efficient HIRF attenuation in aircraft cooling ducts

Radiation incident on aircraft can cause high intensity radiated fields (HIRF) to be present close to electronic systems. This threat is made more serious by the fact that some electronic systems need to be cooled via air ducts on the side of the aircraft, creating leakage points for electromagnetic radiation. One such electronic system is the Full Authority Digital Engine Controller (FADEC). The FADEC is cooled from airflow through a duct called a NACA (National Advisory Committee for Aeronautics) Scoop, located on the side of the engine nacelle. This paper examines the electromagnetic characteristics of the duct and determines the efficiency of existing HIRF protection. The paper also proposes a new method for HIRF protection and considers other applications for the method.