Low level coupling techniques for the HIRF clearance of air systems

Abstract

Current methods for the assessment of military and civil systems for their response to High Intensity Radiated Fields (HIRF) are numerous and varied in their approach. The two principal methods employ either low level techniques for the calculation of transfer functions for extrapolation to high power environments or the use of high power sources specific to the environment to be considered. Low Level Swept (LLS) techniques are commonly used in the certification of both military and civil aircraft to HIRF. This paper examines the Low Level Swept Current (LLSC) technique and demonstrates the effect that the receive antenna height may have on the reference field calibrations. The results of this study show significant variation of up to 10dB which may be directly attributed to the electromagnetic test configuration. Moreover, recommendations are made to reduce measurement uncertainty.