BROCKTON —Ward 5 Councilor Dennis DeNapoli was not surprised to learn that a pirate radio station was traced to the city, but said he was surprised that federal agencies acted to close down the operation.

“We have a lot of illegal radio stations in the city,” said DeNapoli, a radio buff and sometimes talk show host. “They're all over the dial.”

But DeNapoli, who does volunteer work for Brockton WXBR radio, said the area Federal Communications Commission office has turned a deaf ear to complaints by him and others.

“They tell us they're too busy. That was the quote I got from FCC headquarters in Quincy,” DeNapoli said Friday, listing off a number of frequencies he says are broadcasting without licenses and sites in the city where antennas identify radio signals.

The FCC requires that any radio signal equal to 1/4-watt be licensed through that agency, according to DeNapoli.

According to a published report, federal agencies traced a radio signal to a Richmond Street address after that signal interfered with air traffic at Logan International Airport in Boston.

A woman at that address said Friday she was unaware of the enforcement or of any radio station at that location. She identified herself only as the sister of Natacha Souffrant, one of the people named in federal court records ordering the forfeiture of radio equipment, according to a Boston Globe report.

A spokesman at the FCC's headquarters in Washington, D.C., on Friday would not comment on the case involving Logan airport interference because it is an open item before the commission. Nor would she respond to DeNapoli's claim that the area office would not address his complaints.

“We do take complaints of interference very seriously,” she said. “We take all of our complaints very seriously.”

DeNapoli said the pirate radio stations are in private homes and often in warehouses. City inspectors also found a pirate radio station in the second story of a garage in the south side.

He estimated there are 10 or 11 such stations operating in the city, many more in Boston and across the country. Often they interfere with signals of licensed radio operators, including some of the most popular stations in the area, he said.

More importantly, DeNapoli said, the pirate stations are taking advertising revenue that would otherwise go to licensed stations and other media outlets.

“They're selling radio time, that's totally illegal,” he said. “They're foreign language stations — Cape Verdean and Spanish. They just pop up on the dial here, there and everywhere.”

DeNapoli rattled off a series of frequencies he has picked up in his travels around the city.

Setting up a radio station is as simple as buying a transmitter for as little as $500 on the Internet and putting it on the roof of a building.

Because most pirate stations use “cheap” transmitters, he said they are not properly filtered and interfere with or infringe on licensed frequencies.

He said licensed stations need air space that extends below and above the designated frequency and that is where the pirate stations are encroaching, often overriding the legitimate stations.