Modeling HIRF Effects On Aircraft

3rd July 2013

ES Admin

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Whitepaper

Electromagnetic simulation has demonstrated that high intensity radiated fields on the aircraft can have an effect on its electronic system. Radar and satellite communication systems as well as TV and radio stations are all sources of HIRF. Using CST MICROWAVE STUDIO, the overall electromagnetic environmental effects are determined in each frequency band, and transfer functions are measured as a way to predict the behaviour of the aircraft.

The HIRF frequency spectrum is divided in three frequency bands: Low Frequency (LF: 10 kHz 50 MHz) band, Medium Frequency (MF: 30 MHz 400 MHz) band and High Frequency (HF: 100MHz 18/40 GHz) band.

Each frequency band produces different electromagnetic field distributions around and inside an aircraft. In the LF band, the aircraft acts like an antenna and the electromagnetic field penetration into the fuselage is weak, while in the HF band, strong field penetration into the fuselage is seen.

In the MF band, both effects antenna like behaviour and field penetration are superimposed. External fields in the LF and MF band induce currents on the fuselage skin. These may couple into cable harnesses and, as a result, into the aircraft electronics themselves.

The field that penetrates into the fuselage in the HF band may even exceed the external field, due to constructive interference of reflected waves within the fuselage. These strong electromagnetic fields can potentially affect the aircraft electronics directly.

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