The Adcock antenna is an

antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...

array consisting of four equidistant vertical elements which can be used to transmit or receive directional radio waves. The Adcock array was invented and patented by British engineer Frank Adcock in 1919 as

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No. 130,490, and has been used for a variety of applications, both civilian and military, ever since. (Note: The patent lawyer's name appears as inventor, with "F. Adcock" in parentheses, since Lt. Adcock, RE was serving in wartime France at the time.) Although originally conceived for receiving low frequency (LF) waves, it has also been used for transmitting, and has since been adapted for use at much higher frequencies, up to

ultra high frequency Ultra high frequency (UHF) is the ITU designation for radio frequency, radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one ten ...

(UHF). In the early 1930s, the Adcock antenna (transmitting in the LF/MF bands) became a key feature of the newly created

radio navigation Radio navigation or radionavigation is the application of radio frequencies to determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of radiodetermination. The basic principles a ...

system for aviation. The

low frequency radio range The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main Radio navigation, navigation system used by aircraft for instrument ...

(LFR) network, which consisted of hundreds of Adcock antenna arrays, defined the airways used by aircraft for instrument flying. The LFR remained as the main aerial navigation technology until it was replaced by the

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system in the 1950s and 1960s. The Adcock antenna array has been widely used commercially, and implemented in vertical antenna heights ranging from over in the LFR network, to as small as in tactical

direction finding Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio stati ...

applications (receiving in the UHF band).

Radio direction finding

Japanese_Adcock_Antenna_Rabaul_CINCPAC-5-45-3

Frank Adcock originally used the antenna as a receiving antenna, to find the

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al direction a radio signal was coming from in order to find the location of the radio transmitter; a process called radio direction finding. Prior to Adcock's invention, engineers had been using

loop antenna A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that is usually fed by a balanced source or feeding a balanced load. Within this physical description there are two (possibly three) d ...

s to achieve directional sensitivity. They discovered that due to atmospheric disturbances and reflections, the detected signals included significant components of electromagnetic interference and distortions: horizontally polarized radiation contaminating the signal of interest and reducing the accuracy of the measurement. Adcock—who was serving as an Army officer in the British Expeditionary Force in wartime France at the time he filed his invention—solved this problem by replacing the loop antennas with symmetrically inter-connected pairs of vertical monopole or dipole antennas of equal length. This created the equivalent of square loops, but without their horizontal members, thus eliminating sensitivity to much of the horizontally polarized distortion. The same principles remain valid today, and the Adcock antenna array and its variants are still used for radio direction finding.

Low frequency radio range

In the late 1920s, the Adcock antenna was adopted for aerial navigation, in what became known as the low frequency radio range (LFR), or the "Adcock radio range". Hundreds of transmitting stations, each consisting of four or five Adcock antenna towers,A fifth tower was often added in the center of the square for voice transmissions. were constructed around the U.S. and elsewhere. The result was a network of electronic airways, which allowed pilots to navigate at night and in poor visibility, under virtually all weather conditions. The LFR remained as the main aerial navigation system in the U.S. and other countries until the 1950s, when it was replaced by VHF-based

technology. By the 1980s all LFR stations were decommissioned.

References

{{DEFAULTSORT:Adcock Antenna Radio frequency antenna types Antennas (radio)

Radio direction finding

Low frequency radio range

See also

References