Time domain integral equations in EMP shielding performance testing
Testing of electronic equipment and systems against the impact of an electromagnetic impulse (EMP) is a standard procedure for military systems. The EMP couples with the circuitry and cables inside the military equipment, causing current surges and eventually breakdown of semiconductors. EMP shielding is focused on preventing component breakdown by locating points of entry (POE).
During design of military equipment, guidelines aid the designer in EMP shielding. Still, testing is required to guarantee safety. Although experimental testing is possible for smaller systems, for systems aslarge as e.g. naval ships this would become very costly. Numerical modelling in combination with small-scale experimental data is a more cost-effective approach, which would aid in developing a more robust shielding design in a full-threat EMP environment.
A collaboration between the electronic defense department at TNO and the Electromagnetics group has resulted in an implementation of a numerical method for the time-differentiated electric field integral equation (TD-EFIE), to calculate the equivalent surface current density on a perfect electric conductor (PEC) excited by an incoming pulsed electromagnetic plane wave. In the first clip below an example is shown of an electromagnetic Gaussian plane wave polarized in the x-direction and travelling in the negative z-direction, represented by the evolving blue curve in the (x,z)-plane, hitting a 2 m by 2 m PEC plate. The current density in the x-and y-direction (left and right respectively) are plotted on a logarithmic scale.
(MovieTUe/Plate/PlaneWaveGaussianPulsePlate2x2.mp4)
The inhouse built TD-EFIE numerical model has also been tested on other objects such as a 1 m by 1 m by 1 m PEC cube and a sphere with a diameter of 2 m. The movies show the logarithmic current density on the objects due to an incident Gaussian plane polarized in the x-direction and travelling in the negative z-direction, represented by the evolving blue curve in the (x,z)-plane.