Paper on diffusion of reverberant energy

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Paper on diffusion of reverberant electromagnetic energy in enclosed spaces accepted for publication in IEEE Transaction on Electromagnetic Compatibility.

The diffusion equation approach to simulating high-frequency electromagnetic fields has a very low computational cost compared to other applicable techniques, offering the potential for a radical increase in the efficiency of the solution high frequency electromagnetic shielding problems with complex topologies. This paper makes an initial evaluation of the method’s utility for electromagnetic compatibility applications.

Diffusion of diffuse energy between two cavities

The image above shows a cross-sectional view of the the flux of the reverberant energy density at 8 GHz in two cubic cavities coupled by a slot along one edge of the adjoining wall. The cavity on the left has a source of total radiated power 1 watt located near the wall and the cavity on the right contains a highly absorbing cylinder which acts as the “sink” for most of the power. The solution was obtained in under one second on a desktop PC.

The idea of transferring the diffusion equation approach from acoustics to electromagnetics arose from work on using reverberations chambers to study electromagnetic exposure. “Room acoustics” had already been taken over to “room electromagnetics” (Andersen2007) as a method of studying environmental exposure, which led me into the substantial acoustics literature on reverberation. Meanwhile my work on high frequency enclosure shielding effectiveness simulations was demonstrating the huge computational resource required to obtain results using “full-wave” techniques like FDTD.

Full details of the work can be found in the papers (Flintoft and Dawson, 2017; Robinson et al., 2017; Flintoft et al., 2017).


  1. Flintoft, I.D., Marvin, A.C., Funn, F.I., Dawson, L., Zhang, X., Robinson, M.P. and Dawson, J.F., 2017. Evaluation of the diffusion equation for modelling reverberant electromagnetic fields. IEEE Transactions on Electromagnetic Compatibility, 59(3), pp.760–769.
  2. Robinson, M.P., Flintoft, I.D., Dawson, J.F., Marvin, A.C., Funn, F.I., Dawson, L. and Zhang, X., 2017. Effect of loading on field uniformity: Energy diffusion in reverberant environments. In: Proceedings of the XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science. Montreal, Canada, pp.E13–2.
  3. Flintoft, I.D. and Dawson, J.F., 2017. 3D electromagnetic diffusion models for reverberant environments. In: 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA2017). Verona, Italy, pp.511–514.