Analysis and Optimization of Nonlinear Diode Grids for Shielding of Enclosures With Apertures

Lumped-element grids provide an attractive option for wave propagation control in electromagnetic compatibility (EMC) engineering. This article investigates the peak shielding effectiveness (SE) of a diode grid used for protection of enclosures with apertures against high-intensity radiation fields (HIRFs). The nonlinearly loaded aperture is investigated with an efficient hybrid field-circuit simulation approach. Numerical experiments show that design aspects, e.g., aperture and enclosure size, grid density, impedance characteristic of lumped loads, play an important role in the field transmission through a diode grid which is nonlinear and time-variant. With a physics-based analysis of the interaction between the grid and the enclosure-backed aperture, nonlinear shielding techniques are identified that allow a control of the peak SE between 0 and 26 dB in novel ways. For the first time, the peak SE curve of a diode grid is demonstrated with four different field intensity dependencies, i.e., intensity low-pass, intensity high-pass, intensity bandpass, and intensity band-stop selectivities from tens V/m to hundreds of V/m. By considering design aspects into a two-step optimization procedure, practical guidelines are provided for the nonlinear shielding implementation.