Reverberation characteristics of a large welded steel shielded enclosure

For the past several years, there has been an increasing interest in the possibility of testing large items such as aircraft in a reverberation chamber. One of the concerns is the scaleability of the operational characteristics of reverberation chambers. The Naval Surface Warfare Center, Dahlgren Division (NSWCDD) maintains a database on the performance of operating reverberation chambers worldwide. This data consists of stirring ratio data at 1 GHz. Currently there are data from ten chambers in the data base. The volumes of these chambers range from less than 1 m/sup 3/ to about 200 m/sup 3/. The characteristics are scaleable over this two order of magnitude variation in volume. To test a reasonably large aircraft, a chamber would have to have a volume of 5/spl times/10/sup 4/ m/sup 3/ or greater. The two order of magnitude extrapolation for an expensive facility is of concern. An opportunity arose to test an empty cavity with a volume of about 2500 m/sup 3/. This volume is intermediate between that of the chambers in the database and a chamber required for testing large aircraft.