A Rapid Method for Measuring the Volume of a Large Cavity Using Averaged Absorption Cross Section

The rapid and accurate measurement of the volume of a large cavity is much in demand in practice, especially for a cavity of irregular shape. In this paper, a new method is proposed to measure the volume of a large cavity. This method is based on the measurement of the decay time constant of the cavity. A lossy object with a known averaged absorption cross section is used to aid the measurement. By measuring decay time constants of the cavity with and without the lossy object, the cavity volume can be extracted. It is found that only one antenna is required for the measurement and the whole measurement can be completed simply and rapidly. The method could be applied to both metallic and non-metallic cavities which makes the proposed method a very attractive alternative to existing methods.