The Federal Communications Commission’s auction of television airwaves is wrapping up after attracting about $18.2 billion in bids, far less than the last sale of government licenses amid weaker demand.

The complex process freed up spectrum from local TV stations so it could be repurposed for cellular use. But analysts said bidders likely weren’t as interested in the low-frequency television airwaves compared with other airwaves that can carry more data over shorter distances. Participants are barred from talking about the...