UPDATE 1-U.S. FCC says it receives 104 bids to participate in spectrum auction

WASHINGTON/NEW YORK March 18 (Reuters) - The U.S. Federal Communications Commission said on Friday that it had received 104 applications to take part in an auction of valuable low-frequency airwaves relinquished by TV broadcasters, including many wireless companies who want to use the airwaves to build new networks or improve existing coverage.