31 January – Edwin Howard Armstrong first demonstrates the employment of three-element vacuum tubes in circuits that amplify signals to stronger levels than previously thought possible and that could also generate high-power oscillations usable for radio transmission. On 29 October he applies for a United States patent covering the regenerative circuit.[1][2]
Late – Lee de Forest is acquitted of stock fraud in connection with the Radio Telephone Company in the United States.
The Marconi Company initiates duplex transatlantic wireless communication between North America and Europe for the first time, transmitting from Marconi Towers at Louisbourg, Nova Scotia, to Letterfrack in Ireland.
The cascade-tuning radio receiver is introduced.[3]
Lee de Forest publishes a description of his Audiontriode detecting or amplifying vacuum tube.[4]