Simulation for the RCS of the scattering by a dieletric sphere, compared with Mie theory
I follow the build-in Getting Started guide on Radar Cross Section to do a computation on the scattering by a dieletric sphere. The bistatic RCS result from HFSS (even after many refinement passes) still seems to be pretty off from the Mie theory solution.
The PEC cube in the guide is changed into a dielectric sphere of relative permittivity = 2.56. The simulation is done at 300MHz. The distance between PML and sphere is set to be 1 meter > λ/4. The incident wave is a plane wave towards +z, with E-field polarized along x-axis. After 16 adaptive passes, the solution has a delta energy ~ 0.001, and the sphere mesh has about 480k tetrahedrons. The normalized Bistatic RCS on E-plane looks closed to Mie theory, while on H-plane, it looks pretty off.
I check the Mie theory solution, for example in Figure 7.11 (Section 7.4.4) on page 356 from the text book Theory and Computation of Electromagnetic Fields amazon link: https://www.amazon.com/Theory-Computation-Electromagnetic-Fields-Wiley/dp/1119108047/
I would like to know why this discrepancy happens and how to mitigate it. Thanks in advance !