A federal court is expected to rule Wednesday on the effort by the nation's leading broadcast networks to shut down Aereo, a $12-a-month service backed by media entrepreneur Barry Diller that allows users to view network shows any time they wish. Broadcasters claim that the service could Hinder their ability to negotiate retransmission-consent agreements with the major cable outlets. Aereo uses an array of tiny antennas, each one assigned to an individual subscriber, to transmit programs stored in the cloud to mobile devices. It has launched only in New York City, but in an interview with the London Financial Times, Chet Kanojia, Aereo's chief executive officer, said that the company hopes to expand rapidly from a few thousand currently to more than several hundred thousand in New York before moving to other markets.