Analysis of Multi-Layer Composite Cavity Using FEKO

Modeling of a large cavity containing multiple layers inside the structure has been studied using equivalent impedance approximations along with simplified single ray tracing analysis. This modeling effort investigates the effects of radiating with a source enclosed in a large vacant composite structure relative to a short wavelength. The development of the model involves the completion of a two step process. First, the heritage geometric reduction and approximation is investigated. This particular investigation involves an approach that is an application of Poynting's Theorem. This work was performed by Hallett and Reddell at Goddard Space Flight Center in 1998. For this comparison, the Multi-Level Fast Multipole Method (MLFMM) available in the commercial tool FEKO, is used to model a generic multi-layer payload fairing (hollow cone connected to a hollow cylinder) with a radiating source to determine the resonant cavity effects within the fairing as another approximation baseline. The intent is to provide predictions for the electric field levels if a transmitter in the fairing either deliberately or unintentionally is activated. The results show a comparison with the heritage calculation and FEKO software tool. However, FEKO shows the electric field distributions within the composite fairing cavity instead of a single average value.