HIRF penetration into a fuselage-like body: FDTD predictions vs. measurements

The ability of the finite-difference time-domain (FDTD) method to readily handle complex structures having a complex mix of materials makes it suitable for predicting the penetration of high intensity radiated fields (HIRF) fields into aircraft fuselages. This paper summarizes the next step in ASU´s on-going research into developing the computational tools that are needed to predict this HIRF penetration. The shielding effectiveness, a measure of field penetration, of a 1:20 scaled simplified aircraft fuselage was predicted using the FDTD method and was compared with measurements. To accelerate the FDTD solution of this relatively high-Q structure, a resistive source model was used, and the time-domain fields were windowed prior to Fourier transformation into the frequency domain. A reasonable level of agreement was observed between measurement and prediction at the lower frequencies of the 0.25 GHz to 9 GHz band considered. At the higher frequencies, the measurement and prediction are not in close agreement, deterministically. However, the envelope of the predicted shielding effectiveness continues to compare favorably at the higher frequencies with that measured, suggesting that a statistical approach may be appropriate.