Comments on ”A new conformal FDTD for lossy thin panels”

In the paper ”A new conformal FDTD for lossy thin panels” by M. R. Cabello et al., the appearance of spiky antiresonances in the simulation of the shielding properties of lossy thin-shell spherical cavities by FDTD, was categorised as spurious solutions. In this document, we briefly clarify this topic, and show that these solutions are not really spurious in the common interpretation of the term. Actually, they correspond to physical solutions, appearing due to lack of symmetry inherent to the staggered co-location nature of field components in FDTD.