The ornamental design for a supportingmeans for antenna, as shown and described.
FIG. 1 is a perspective view of a supporting means for antenna showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view thereof in use.
The broken line showing of an antenna and second supporting means in FIG. 8 is included for the purpose of illustrating environment and forms no part of the claimed design.