We claim the ornamental design for an electromagnetic field apparatus, as shown and described.
FIG. 1 is a top, side perspective view of an electromagnetic field apparatus comprising the present invention.
FIG. 2 is a top, rear perspective view of the apparatus shown in FIG. 1.
FIG. 3 is a left side elevational view of the apparatus shown in FIGS. 1 and 2. The right side elevational view is a mirror image of the left side elevational view.
FIG. 4 is a front elevational view of the apparatus shown in FIGS. 1, 2, and 3; and,
FIG. 5 is a top plan view of the apparatus shown in FIGS. 1, 2, 3, and 4.
The broken lines in FIGS. 2 and 5 are included for the purpose of illustrating a portion of the electromagnetic field apparatus that forms no part of the claimed design.