External radiation of complex cavities described by the random coupling model

This paper considers the problem of coupling of an external radiation to the field of a cavity with irregular shape. In particular, the connections of a statistical model based on random matrix theory, called random coupling model, to deterministic models is explored. The canonical expansion of cavity fields in eigenmodes is preserved, and the coupling of an incoming plane-wave is supposed to take place through a narrow aperture radiating inside the cavity. The fluctuation of the aperture radiation admittance is investigated in various cavity loss conditions. Obtained results constitute the basis for understanding the energy propagation through tightly coupled environments.