AN ALTERNATIVE DESCRIPTION OF THE MAGNETIC CURRENT ANNULAR RING (FRILL) SOURCE

摘要

An alternative method is presented of considering, and of deriving expressions for the fields generated by, an annular ring of magnetic current (magnetic frill source). The magnetic frill appears to offer a means of numerical model excitation that is more realistic than the pulse source and, moreover, provides analytical expressions for fields in some cases. The fields for the magnetic frill source were first derived by Tsai from the electric vector potential produced by the magnetic current. The method described shows the source to resemble a toroidal transformer and the field expressions are derived from the magnetic vector potential produced by electric currents. The expressions derived are, in essence, the same as those of Tsai, but it is considered that the method yields greater physical insight into the source and so facilitates modification to suit particular applications. Tsai's expression which is of most interest for numerical calculations is derived by inspection using the method described. For calculations using point matching however, the benefits of using the frill source seem more apparent than real. [Vol. 5, No. l, pp. 47-62 (1990)]