Perfect is a big word! If you are talking FDTD simulations, if it to stop things re-entering the model the trick is to match the refractive index of your immersive absorber with your model's (i.e. no reflections) and a really high absorption coefficient. (solvers are engineering, will need to translate properties to complex permittivity or permittivity+conductivity. )
In real life? Water absorption is very high - 50/cm to 1000/cm in your range, graphene may be good. Depends what you are wanting to do.
Farklı Frekans aralığında farklı mükemmel emici olan malzemeler elde edilebilir. Bu elde etmek istediğimi malzemenin özelliğine ve yapacağımız çalışmaya bağlıdır.