Transmission Cross Sections of Apertures Measured by Use of Nested Mode-StirredChambers (Maetning av Aperturers Transmissionstvaersnitt med Laenkade Modvaexlande Kammare)

摘要

Knowledge of the transmission cross section of apertures, sigma(sub a)constitutes an important factor in design and analysis of electrically large shielded structures. This report presents a recently developed method to measure sigma(sub a), between 200 MHz and 18 GHz, by use of nested mode-stirred chambers. After an introduction giving the rationale for the work, the report describes the measurement system and measured properties of the chambers. It also includes a theoretical outline of the electromagnetic properties of the mode-stirred chamber. The measurement method is validated using a circular aperture, for which an exact solution of sigma(sub a) exists. Measured results are also presented for several other types of apertures. These include simple, generic, ones as well as apertures of more complex shape, e.g. riveted seams.