Normalized field strength value improvement method for aircraft system-level HIRF test using reverberation chamber method

During the HIRF (RS) test of the C919 aircraft's flight control system-level reverberation room method, the normalized field strength obtained by calibration is lower than the reverberation chamber cavity value, which may adversely affect the test results. Analysis of the test layout and process found that bubble plate area for paving the equipment instrument, the number of stirring steps of mixer in the reverberation chamber, and the overall electromagnetic reflection and shielding properties of the system can affect the normalized field strength of the calibration. Controlled variable tests were conducted on different foam board areas, different stirring steps of the mixer, and whether to use a large area of copper mesh to wrap non-tested equipment to enhance the overall electromagnetic reflectivity and shielding of the system. The test results show that reducin g the area of the foam board can slightly improve the normalized field strength value during the calibration process, while increasing the number of stirrer steps and using a large area of copper mesh to wrap non-tested equipment, cables and oil pipes can significantly improve the value. The three measures are implemented simultaneously to make the normalized field strength meet the requirements of the test field strength conditions.