Characteristics of Fields From Lightning Test Currents in the Presence of a Nearby Finite-Size Metal Plate

To analyze the public in situations of simultaneous exposure to fields with different frequencies, the common lightning test current of 8/20 μs is employed to perform numerical and experimental analysis. First, the energy distribution of the exciting source in different frequency bands is given. Then, the induced magnetic field at different observation points is calculated, and the influence of finite-size metal plates with different materials, dimensions, and buried depth on the magnetic field propagation characteristics are discussed as well. The numerical and experimental results suggest that the energy of 8/20 μs is mainly concentrated below 1 MHz, the working space of lightning surge generator is in general electrically small compared to its wavelength. Due to the fact that the coupled energy is limited, it is not necessary to totally shield the impact laboratory according to the reference levels for general public exposure.