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A sense antenna normally consists of a single vertical antenna positioned some distance from the crossed loops, in line with one of the two loops, at a distance about the same as the distance between the two vertical portions of the loop. The sense antenna's output is mixed with the loop it is in-line with, through a switch that allows it to be ...
RDF systems using mechanically swung loop or dipole antennas were common by the turn of the 20th century. Prominent examples were patented by John Stone Stone in 1902 (U.S. Patent 716,134) and Lee de Forest in 1904 (U.S. Patent 771,819), among many other examples.
Ferrite antennas are usually enclosed inside the radio receiver. Ferrite loop antennas are made by winding fine wire around a ferrite rod. They are almost universally used in AM broadcast receivers. [12] (p 23) [d] Other names for this type of antenna are loopstick, ferrite rod antenna or aerial, ferroceptor, or ferrod antenna.
When the loop is aligned at right angles to the signal, the signal in the two halves of the loop cancels out, producing a sudden drop in output known as a "null". Early DF systems used a loop antenna that could be mechanically rotated. The operator would tune in a known radio station and then rotate the antenna until the signal disappeared.
Loop antennas interact directly with the magnetic field of the radio wave, rather than its electric field as linear antennas do; for that reason they are on rare occasions categorized as magnetic antennas, but that generic name is confusingly similar to the term magnetic loop normally used to describe small loops.
The rhombic antenna was designed in 1931 by Edmond Bruce [1] and Harald Friis, [2] [3] It was mostly commonly used in the high frequency (HF) or shortwave band as a broadband directional antenna. As of 2023, one last remnant pole still stands from the AT&T pole farm which was located in Mercer County, New Jersey
A quad antenna is a type of directional wire radio antenna used on the HF and VHF bands. A quad is a Yagi–Uda antenna ("Yagi") made from loop elements instead of dipoles: It consists of a driven element and one or more parasitic elements ; however in a quad, each of the loop elements may be square, round, or some other shape.
The Adcock antenna is an antenna 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 and since his August 1919 British Patent No. 130,490, the 'Adcock Aerial' has been used for a variety of ...