Key points are not available for this paper at this time.
The concept of fractional curl operator is introduced, and as one of its roles, it is briefly shown that the duality principle in electromagnetism for the source-free case can be fractionalized. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 17: 86–91, 1998.
Nader Engheta (1998) studied this question.