Errors modelling very lossy arbitrary 3D structures with commercial solvers

Commercial modelling packages (e.g. HFSS and COMSOL) cannot accurately model very lossy arbitrary 3D structures. This problem is clearly explained in the following paper:

S. Papantonis and S. Lucyszyn, ?Lossy spherical cavity resonators for stress-testing arbitrary 3D Eigenmode solvers?, PIER Journal, vol. 151, pp. 151-167, May 2015

This paper is open access and can be downloaded from:

http://www.jpier.org/PIER/pier.php?volume=151