I claim the ornamental design for a beacon, as shown and described.
FIG. 1 is a top perspective view showing the beacon;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a front view thereof, which is a mirror image of the right-side view thereof;
FIG. 6 is a left-side view thereof; and,
FIG. 7 is a rear view thereof.
The broken lines in the drawings are for the purpose of illustrating unclaimed portions of the beacon and form no part of the claimed design.
The shading lines shown in the drawings represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.