Experimental and numerical analysis of a carousel stirrer for reverberation chambers
The paper analyzes the performance of a reverberation chamber equipped by a “carousel” stirring system. The working volume is positioned inside the stirrer rotating volume. More precisely, the carousel consists of several vertical strips that rotate around a central axis and having a total diameter as large as possible compared to chamber dimensions. An FDTD code, optimized for reverberation chamber simulations and tested with experimental results, is used to analyze the chamber performance as function of strip number and width. The proposed setup increases the working volume and improves the reverberation chamber behavior with respect to a traditional setup. Moreover, it needs just one motor to control the stirrer, and it does not require more complex mechanical part. All simulations are compared to measurements showing a good agreement.
Stirring performance of helically distributed paddles
The performance of a rotating stirrer made of helically positioned paddles is experimentally analyzed. The statistically independent positions are computed as a function of the number of paddles, paddle separation and relative tilt angle. With respect to a traditional single paddle wheel stirrer, the structure combines a helical path and just a simple engine required for the rotation. The analysis reveals an improvement in the lower frequency range where the chamber performance is more critical. The number of the paddles is limited by the distance and the tilt angle. The correlation between two adjacent paddles is also analyzed as function of the distance and the tilt angle. The activity suggests the need for optimization of all parameters.
A Reciprocity Approach for Computing the Response of Wiring Systems to Diffuse Electromagnetic Fields
This paper is concerned with the problem of computing the response of a wiring system to a high frequency, short wavelength, electromagnetic field, such as that which can arise in the interior of an irradiated vehicle. It is shown that a “diffuse-field reciprocity principle” developed recently in the field of vibroacoustics can be applied to electromagnetic systems, thus, enabling the currents induced in a wiring system by diffuse electromagnetic waves to be computed in an efficient manner. With this approach only the radiation characteristics of the wiring system are required to be computed; more specifically, the impedance matrix associated with radiation into an infinite dielectric is required, and an efficient method of computing this matrix is given in the present paper, based on exact solutions to Maxwell's equations. Initially, the diffuse-field reciprocity principle is proved explicitly for one- and two-wire systems, and the method is then applied to numerical examples involving these systems. The applicability of diffuse-field theory to high-frequency interior reverberant electromagnetic fields has been verified analytically and experimentally in recent years, and this paper offers the possibility of exploiting these developments to avoid large-scale electromagnetic compatibility computations.