A discone antenna is a version of a

biconical antenna In radio systems, a biconical antenna is a broad-bandwidth antenna made of two roughly conical conductive objects, nearly touching at their points.Zhuohui Zhang,''Analysis and design of a broadband antenna for software defined radio'', ProQuest, 2 ...

in which one of the cones is replaced by a disc. It is usually mounted vertically, with the disc at the top and the cone beneath.

Omnidirectional Omnidirectional refers to the notion of existing in every direction. Omnidirectional devices include: * Omnidirectional antenna, an antenna that radiates equally in all directions * VHF omnidirectional range, a type of radio navigation system for ...

, vertically polarized and with

gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in de ...

similar to a dipole, it is exceptionally wideband, offering a frequency range ratio of up to approximately 10:1. The radiation pattern in the

vertical plane In astronomy, geography, and related sciences and contexts, a '' direction'' or ''plane'' passing by a given point is said to be vertical if it contains the local gravity direction at that point. Conversely, a direction or plane is said to be hor ...

is quite narrow, making its sensitivity highest in the direction of the

horizon The horizon is the apparent line that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This line divides all viewing directions based on whether i ...

and rather less for signals coming from relatively close by.

History

On February 6, 1945, Armig G. Kandoian of

New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...

was awarded

U.S. patent Under United States law, a patent is a right granted to the inventor of a (1) process, machine, article of manufacture, or composition of matter, (2) that is new, useful, and non-obvious. A patent is the right to exclude others, for a limited ...

number (assignor to Federal Telephone and Radio Corporation, later merged with

ITT Corporation ITT Inc., formerly ITT Corporation, is an American worldwide manufacturing company based in Stamford, Connecticut. The company produces specialty components for the aerospace, transportation, energy and industrial markets. ITT's three businesses ...

), from an application made on May 15, 1943. Excerpt from the Kandoian patent:

In keeping with progress made during the last few years in the development of ultra-high frequency
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
technique, and applications thereof to
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
communication, direction finding, and so forth, it has become necessary to develop special antennas and antenna systems suitable for installation on such aircraft. Flying conditions are such that these antennas must necessarily be small and rigid in their construction and also offer a minimum of
wind resistance In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...
, in order that the flying efficiency of the aircraft will be unimpaired. In accordance with my invention I have provided a small rigid antenna suitable for mounting on the surface of the
fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...
or other component of the airplane structure and in certain embodiments I have also provided a streamlined protecting shield or housing covering or so cooperating with the construction of the antenna system as to greatly reduce wind resistance.

Description

The discone antenna has a useful frequency range of at least 10 to 1. When employed as a transmitting antenna, it is often less efficient than an antenna designed for a more limited frequency range. SWR ( standing wave ratio) is typically 1.5:1 or less over several octaves of frequency. A discone antenna consists of three main parts: the disc, the cone, and the insulator. * The disc: The disc should have an overall diameter of 0.7 times a quarter

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...

of the antenna's lowest

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

. The antenna's feed point is at the center of the disc. It is usually fed with 50-ohm

coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...

, with the center conductor connected to the disc, and the outer conductor to the cone. * The cone: The length of the cone should be a quarter wavelength of the antenna's lowest operating frequency. The cone angle is generally from 25 to 40 degrees. * The insulator: The disc and cone must be separated by an insulator, the dimensions of which determine some of the antenna's properties, especially on near its high frequency limit.

Construction materials

A discone may be made from solid metal sheet (often

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

), which is practical for small indoor UHF antennas, such as for

Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wave ...

. At lower frequencies a sufficient number of metal wires or rods in a

spoke A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. The term originally referred to portions of a log that had been riven (split l ...

configuration is often used to approximate a solid surface. This simplifies construction and reduces wind loading. The spokes may be made of stiff wire, brazing rods or even coat hanger wire. The optimal number of rods comprising the disc and cone is often quoted as being from 8 to 16.

Applications

The discone's wideband coverage makes it attractive in commercial, military,

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

and radio scanner applications. The discone's inherently wideband nature permits it to broadcast undesirable spurious emissions from faulty or improperly filtered

transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna (radio), antenna. The transmitter itself generates a radio frequency alternating current, which i ...

Extending low-frequency response

A vertical whip may be affixed to the center of the disc in order to extend the low frequency response, but this may compromise efficiency at higher frequencies. In this configuration, at lower frequencies the discone may more closely resemble a ground plane antenna or a coaxial dipole.

References

External links

UHF Discone Antenna

Parabolic Discone (Michael Lake KD8CIK)

Broadband radial discone antenna: Design, application and measurements

Discone antenna basics
{{Antenna Types Radio frequency antenna types Antennas (radio)