Antenna types

Isotropic

Dipole

• Turnstile – Two dipole antennas mounted at right angles, fed with a phase difference of 90°. This antenna is unusual in that it radiates in all directions, with horizontal polarization in directions coplanar with the elements, circular polarization normal to that plane, and elliptical polarization in other directions. Used for receiving signals from satellites, as circular polarization is transmitted by many satellites.
• Corner reflector – A directive antenna with moderate gain of about 8 dBi often used at UHF frequencies. Consists of a dipole mounted in front of two reflective metal screens joined at an angle, usually 90°. Used as a rooftop UHF television antenna and for point-to-point data links.
• Patch – A type of antenna with elements consisting of metal sheets mounted over a ground plane. Similar to dipole with gain of 6–9 dBi. Integrated into surfaces such as aircraft bodies. Their easy fabrication using PCB techniques have made them popular in modern wireless devices. Often combined into arrays.

  Monopole

• Whip – Type of antenna used on mobile and portable radios in the VHF and UHF bands such as boom boxes, consists of a flexible rod, often made of telescoping segments.
• Rubber ducky – Most common antenna used on portable two-way radios and cordless phones due to its compactness, consists of an electrically short wire helix. The helix adds inductance to cancel the capacitive reactance of the short radiator, making it resonant. Very low gain.
• Ground plane – a whip antenna with several rods extending horizontally from base of whip attached to the ground side of the feedline. Since whips are mounted above ground, the horizontal rods form an artificial ground plane under the antenna to increase its gain. Used as base station antennas for land mobile radio systems such as police, ambulance and taxi dispatchers.
• Mast radiator – A radio tower in which the tower structure itself serves as the antenna. Common form of transmitting antenna for AM radio stations and other MF and LF transmitters. At its base the tower is usually, but not necessarily, mounted on a ceramic insulator to isolate it from the ground.
• Folded unipole antenna – is a modified mast antenna, usually grounded at its base, augmented by one or several parallel wires called "skirt wires" that attach to the mast part-way up the antenna. The skirt wires can attach at any height between part-way up and the top of the mast. One or more of the skirt wires is fed with the signal, similar to a gamma match. The number and relative thickness of the mast and the skirt wires adjusts the impedance magnitude at the feedpoint. Further, the fed wire and the mast form a vertically aligned loop which inductively loads the antenna, with the inductance controlled by the height of the attachment point.
• T and inverted L – Consist of a long horizontal wire suspended between two towers with insulators, with a vertical wire hanging down from it, attached to a feedline to the receiver or transmitter. Used on LF and VLF bands. The vertical wire serves as the radiator. Since at these frequencies the vertical wire is electrically short, much shorter than a quarter wavelength, the horizontal wire serve as a capacitive "hat" to increase the current in the vertical radiator, increasing the gain. Very narrow bandwidth, requires loading coil to tune out any remaining capacitive reactance. Requires low resistance ground.
• Inverted F – Combines the advantages of the compactness of inverted-L antenna, and the good matching of the F-type antenna. The antenna is grounded at the base and fed at some intermediate point. The position of the feed point determines the antenna impedance. Thus, matching can be achieved without the need for a separate matching network.
• Umbrella – Very large wire transmitting antennas used on VLF bands. Consists of a central mast radiator tower attached at the top to multiple wires extending out radially from the mast to ground, like a tent or umbrella, insulated at the ends. Extremely narrow bandwidth, requires large loading coil and low resistance counterpoise ground. Used for long range military communications.

  Array

• Collinear – Consist of a number of dipoles in a vertical line. It is a high-gain omnidirectional antenna, meaning more of the power is radiated in horizontal directions and less wasted radiating up into the sky or down onto the ground. Gain of 8–10 dBi. Used as base station antennas for land mobile radio systems such as police, fire, ambulance, and taxi dispatchers, and sector antennas for cellular base stations.
• Yagi–Uda – One of the most common directional antennas at HF, VHF, and UHF frequencies. Consists of multiple half-wave dipole elements in a line, with a single driven element and multiple parasitic elements which serve to create a uni-directional or beam antenna. These typically have gains between 10–20 dBi depending on the number of elements used, and are very narrow band though there are derivative designs which relax this limitation. Used for rooftop television antennas, point-to-point communication links, and long distance shortwave communication using skywave reflection from the ionosphere.
• Log-periodic dipole array – Often confused with the Yagi-Uda, this consists of many dipole elements along a boom with gradually increasing lengths, all connected to the transmission line with alternating polarity. It is a directional antenna with a wide bandwidth. This makes it ideal for use as a rooftop television antenna, although its gain is much less than a Yagi of comparable size.
• Reflective array – Multiple dipoles in a two-dimensional array mounted in front of a flat reflecting screen. Used for radar and UHF television transmitting and receiving antennas.
• Phased array – A high gain antenna used at UHF and microwave frequencies which is electronically steerable. It consists of multiple dipoles in a two-dimensional array, each fed through an electronic phase shifter, with the phase shifters controlled by a computer control system. The beam can be instantly pointed in any direction over a wide angle in front of the antenna. Used for military radar and jamming systems.
• Curtain array – Large directional wire transmitting antenna used at HF by shortwave broadcasting stations. It consists of a vertical rectangular array of wire dipoles suspended in front of a flat reflector screen consisting of a vertical "curtain" of parallel wires, all supported between two metal towers. It radiates a horizontal beam of radio waves into the sky above the horizon, which is reflected by the ionosphere to Earth beyond the horizon.
• Half-square antenna – A pair of ground-isolated, quarter-wave vertical monopoles, whose tops are connected by a line one half-wavelength long. The verticals are the radiators and function as a two-element array, similar to the bobtail curtain. The structure is shaped like the Greek letter Π. The top-to-top connecting wire serves as a phased feedline, or an auxiliary feed, which puts the point of maximum current at the top of each monopole. Neither monopole element has a wire connection to the ground beneath it. Top-fed monopoles produce a strong signal low to the horizon, as opposed to an ordinary bottom-fed monopoles. The feedpoint for the combined system may be placed at any of several locations.
• Batwing or superturnstile – A specialized antenna used in television broadcasting consisting of perpendicular pairs of dipoles with radiators resembling bat wings. Multiple batwing antennas are stacked vertically on a mast to make VHF television broadcast antennas. Omnidirectional radiation pattern with high gain in horizontal directions. The batwing shape gives them wide bandwidth.
• Microstrip – an array of patch antennas on a substrate fed by microstrip feedlines. Microwave antenna that can achieve large gains in compact space. Ease of fabrication by PCB techniques have made them popular in modern wireless devices. Beamwidth and polarization can be actively reconfigurable.

  Loop

Large loops

• Large loops – Loops with perimeter of a full wavelength, two wavelengths, or any whole-number multiple of a full-wavelength, are naturally resonant and act somewhat similarly to the full-wave or multi-wave dipole. When it is necessary to distinguish them from small loops, they are called "full-wave" loops.
• Quad – Although "quad" can refer to a single quadrilateral-shaped loop, the term usually refers to two or more loops stacked side by side; at first glance, quads resemble a box kite frame. One loop in the quad is connected to the feedline and functions as the driver for the antenna and is the main signal radiator, while the others are parasitic element that act as resonators, increasing the gain. Quad antennas function analogously to Yagi-Uda antennas made with loops, and are similarly used as a directional antennas on the HF bands for shortwave communication. They are sometimes preferred for longer wavelengths because they are half as wide as a Yagi.
• Half-loop – A ground-mounted upper half of a full-wavelength loop antenna. The full loop is cut at two opposite points along its perimeter, and the lower half is omitted. It is shaped like the Greek letter Π or an upside-down capital letter U, and is the loop antenna analog of a ground-mounted monopole antenna. Like a vertical monopole, the missing lower half of the antenna is replaced by its ground-plane image. If shaped like a half of a square, a half-loop can operate either as a loop antenna or, on its first harmonic, as a dipole antenna whose ends have been bent over and grounded, depending on the form and location of the feed-point.

  In between

• Halo antennas – Loops that are exactly one half-wavelength in perimeter – with a small gap cut in the loop – are called "halo antennas" and are intermediate in form and function between small and large loops. They are often described as a half-wavelength dipole that has been folded into a circle, rather than being a true loop antenna.

  Small loops

• Small loops – If the loop perimeter is smaller than a half-wavelength, the loop must be modified in some way to make it resonant, if resonance is necessary. Small loops are called "magnetic loops", and if modified for resonance they are also called "tuned loops". Their directionality and radiation efficiency is drastically different from full-wave loops. Small loops are widely used as compact direction finding antennas.
• Ferrite – Loopstick antennas are omnidirectional around their axes, and are premier examples of small loop antennas. They are the magnetic analogue of the short dipole antenna. These are used as the receiving antenna in most consumer AM radios operating in the medium wave broadcast band. Wire is coiled around a ferrite core which greatly increases the coil's inductance and its effective signal-capturing area. The radiation pattern is maximum at directions perpendicular to the ferrite rod. The null direction of ferrite core antennas are bi-directional and much sharper than the maximal directionality. This often makes the direction of the null more useful for locating a signal source than the direction of the strongest signal. The null direction of small loops can also be exploited to reject unwanted signals from an interfering station or noise source.

  Conical

• biconical antenna is a dipole-like antenna made of two cones, oriented along the same axis and oriented tip-to-tip.
• Butterfly antenna is a two-dimesional biconical antenna.
• discone antenna is half of a biconical with a flat disc mounted above the cone

Aperture

• Parabolic – The most widely used high gain antenna at microwave frequencies and above. Consists of a dish-shaped metal parabolic reflector with a feed antenna at the focus. It can have some of the highest gains of any antenna type, up to 60 dBi, but the dish must be large compared to a wavelength. Used for radar antennas, point-to-point data links, satellite communication, and radio telescopes
• Horn – a simple antenna with moderate gain of 15 to 25 dBi that consists of a flaring metal horn attached to a waveguide. Used for applications such as radar guns, radiometers and as feed antennas for parabolic dishes.
• Slot – consists of a waveguide with one or more slots cut in it to emit the microwaves. Linear slot antennas emit narrow fan-shaped beams. Used as UHF broadcast antennas and marine radar antennas.
• Lens – a lens antenna consists of layer of dielectric or a metal screen or multiple waveguide structure of varying thickness in front of a feed antenna, which acts as a lens which refracts the radio waves, focusing them on the feed antenna.
• Dielectric resonator – consists of small ball or puck-shaped piece of dielectric material excited by aperture in waveguide Used at millimeter wave frequencies

  Traveling wave

• Beverage – Simplest unidirectional traveling-wave antenna. Consists of a straight wire one to several wavelengths long, suspended near the ground, connected to the receiver at one end and terminated by a resistor equal to its characteristic impedance, 400–800 Ω at the other end. Its radiation pattern has a main lobe at a shallow angle in the sky off the terminated end. It is used for reception of skywaves reflected off the ionosphere in long distance "skip" shortwave communication.
• Rhombic – Consists of four equal wire sections shaped like a rhombus. It is fed by a balanced feedline at one of the acute corners, and the two sides are connected to a resistor equal to the characteristic resistance of the antenna at the other. It has a main lobe in a horizontal direction off the terminated end of the rhombus. Used for skywave communication on shortwave bands.
• Leaky wave – Microwave antennas consisting of a waveguide or coaxial cable with a slot or apertures cut in it so it radiates continuously along its length.
• Helical – Consists of a wire in the shape of a helix mounted above a reflecting screen. It radiates circularly polarized waves in a beam off the end, with a typical gain of 15 dBi. It is used at VHF and UHF frequencies where antenna sizes are feasible. Often used for satellite communication, which uses circular polarization because it is insensitive to the relative rotation on the beam axis. When a helical antenna has about 10 turns or more, each turn a full wavelength, then it is a form of traveling-wave antenna. If it only has a few turns and the turns' totaled circumference is one or a few wavelengths, then it is some variety of a large loop antenna. When the totaled circumference of all the turns taken together is less than one wavelength, then the helix is a continuously-loaded monopole, called a "rubber ducky antenna", or a "Slinky" antenna, or a "broomstick" antenna.

  Other antenna types

• Random wire – This describes the typical antenna used to receive shortwave radio, consisting of a random length of wire either strung outdoors between supports or indoors in a zigzag pattern along walls, connected to the receiver at one end. The antenna typically will have complex radiation patterns with several lobes at angles to the wire, in different directions for each fold in the antenna. Random wire antennas typically are categorized as folded monopole antennas if their lengths are two wavelengths or less, but operate similarly to traveling-wave antennas when they are laid out in a straight line several wavelengths long.