permanent echo

American  

noun

Electronics.

1. a radar signal reflected to a radar station on the ground by a building or other fixed object.

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Example Sentences

Dunnavant, who will be on hand at Monday’s suburban summit, said every Republican in these regions needs to work on “practical things” that relate to these neighborhoods and communities in ways that cut through the permanent echo chamber of national news.

From Washington Post

Strange rotating red, blue, green and white flashing lights seen by police officers in the English towns of Boston and Skegness and also detected on radar turned out to be nothing more unusual than bright stars and “a ‘permanent echo’ created by a tall church spire in the Lincolnshire Wolds.”

From New York Times