Steamship wireless T antenna

Typical wireless antenna on a steamship in 1914. This was a type called a T aerial, consisting of several horizontal wires suspended from spreaders between two masts, with vertical feeder wires connected to the center extending down to the transmitter in the radio cabin. The vertical wires served as a monopole radiator, while the horizontal wires served as a "top-load", adding capacitance to the antenna to increase the current in the vertical radiators. One of the first uses for radio was on ships, to keep in touch with shore and call for help in the event the ship was sinking. High profile rescues like the sinking of the RMS Titanic had prompted the US Congress to require in 1912 that all ships over a certain tonnage carry wireless gear that was manned at all times. The spark-gap transmitters in use at this time could not transmit speech but transmitted information by wireless telegraphy; the transmitter was turned off and on rapidly by the operator to spell out messages in Morse code. Ship wireless used wavelengths of 300-600 meters (500 kHz - 1 MHz) with radiated power of 500 - 5000 W. The Marconi Co. had a virtual monopoly on ship wireless, since its operators were forbidden to

Date

1914

Photographer / author

Charles R. Gibson

Archive

Wikimedia Commons

Type

image

Original size

1,668 × 1,076 pixels

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