Goliath transmitter

Goliath transmitter was a very low frequency transmitter for communicating with submarines, built by Nazi Germany's Kriegsmarine navy near Kalbe an der Milde in Saxony-Anhalt, Germany, which was in service from 1943 to 1945. It was capable of transmission power of between 100 and 1000 kW and was the most powerful transmitter of its time.
Submarines are shielded by conducting seawater from ordinary radio communication frequencies, but radio waves in the very low frequency band from 30 to 3 kHz can penetrate seawater to depths of about 50 feet, allowing submarines to receive communications without surfacing and becoming vulnerable to detection. From 1943 to the end of World War II, Goliath was the main radio transmitter for German submarine radio communications, operating on frequencies between 15 and 25 kHz with a main working frequency of 16.55 kHz. Transmitting up to 1000 kilowatts of power, Goliath's transmissions could be received worldwide including submerged submarines in the Caribbean, but had difficulty penetrating Norwegian fjords.

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