Frequency characterization of reverberation chambers

A series of measurements to investigate the modal structure of a reverberation chamber were conducted at the Dahlgren Division of the Naval Surface Warfare Center, Dahlgren, Virginia. These measurements were Phase I of a project to determine the frequency dependent characteristics of the fields in a reverberation chamber. Measurements were taken to compare the modal structure excited by both CW and band limited white Gaussian noise. Measurements were also obtained to determine the required step size for collecting field characterization data using discrete frequency data. The measurements were taken over frequency bands ranging from 1 MHz to 100 MHz using frequency steps from 0.1 to 100 kHz. The frequency bands selected covered frequencies from below the first chamber resonance to 18 GHz. Each frequency band was evaluated for multiple boundary conditions (i.e. independent positions of the paddle wheel tuner). The data collected were analyzed to determine the width of the peaks that occur within the chamber as a function of frequency. The results of the analysis yielded the uncertainty of obtaining the true peak of the fields in the chamber as a function of the width of the frequency band and size of the frequency step.