The Adcock antenna array has been widely used commercially, and implemented in vertical antenna heights ranging from over 130 feet (40 meters) in the LFR network, to as small as 5 inches (13 cm) in tactical direction finding applications (receiving in the UHF band).
The earliest experiments in RDF were carried out in 1888 when Heinrich Hertz discovered the directionality of an open loop of wire used as an antenna.
During World War I he established the principles that led to sound-type directional finders.
;N0N : Continuous, unmodulated carrier - as previously commonly used for radio direction finding (RDF) in marine and aeronautical navigation.
After a spell as Deputy Director of Signals, he was appointed the Director of Radio in 1941, the Director of RDF in 1942 when he was promoted to Air Vice-Marshal.
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In the evening of 20 June 1942, while patrolling two miles off the coast of British Columbia, I-26 surfaced and shelled the lighthouse and radio-direction-finding (RDF) installation at Estevan Point.