FDTD simulations used to correct for ground effects during aircraft illumination tests

Aircraft illumination tests are carried out by exposing the aircraft with electromagnetic radiation, while at the same time induced currents on internal cables are measured. In this paper, a method is described in which FDTD simulations are used to derive a frequency-dependent correction factor K(f) describing the differences between the test setup and the free-flight situation one actually would like to study. The underlying assumptions of the method are justified using results from simulations of a generic object. Also, the method is applied to the Saab 39 Gripen fighter aircraft. A detailed statistical analysis of the simulation results yields a single function K(f), which can be used to transform the measured cable currents to those expected during a representative free-flight illumination situation