Development and investigation of approximate phenemonological models for the coupling of electromagnetic energy through apertures into enclosures

The development and investigation of approximate phenomenological models used for the estimation of the coupling of electromagnetic energy through apertures into enclosures is presented in this thesis. Some theoretical aspects of the electromagnetic field penetration into a rectangular enclosure through apertures are reviewed. It is shown that for a simple system topology analytical formulations based on a transmission model of shielding give good predictions of the shielding effectiveness of a rectangular enclosure with apertures. Higher-order modes or enclosure “signatures” included in the developed model expand phenomenological understanding at higher frequencies while the incidence and polarization angle of the incoming electromagnetic field extend the model applicability. Losses can be easily incorporated in the transmission-line modelling of higher-order modes and may be used to mimic the loading effect of electronics. The aperture-enclosure resonant condition is defined for the transmission-line model. Knowledge of the resonant condition allows one to detune the enclosure at the design stage. The developed models are validated by comparing the shielding effectiveness predictions with full-field simulations using the finite-difference time-domain technique and experimental investigations of the shielding effectiveness in an anechoic chamber. It is demonstrated that this analytical approach to shielding effectiveness estimation of a rectangular enclosure with apertures provides a cost-effective alternative to numerical methods, thus saving significant computing resources.