Just connect one end to the radio's whip antenna and stick the other end into
the big, round ground pin of a wall socket. Loop the bared end so it will stay
in the socket and make good contact, too.

That ground pin is at DC ground but way above RF ground. Too, the ground wire
will couple off signals from those long hot wires. Be prepared, though, for
overloading from nearby MW stations.

A more elegant way would be to put an alligator clip on the radio end of the
wire and a banana pin on the socket end.

Note: This suggestion is only for U.S. and similar three-prong AC outlets.

Bill, K5BY