UHF television antenna on a residence. This type of antenna, called a Yagi-Uda antenna, is widely used at UHF frequencies.
A stack of "fishbone" and Yagi–Uda television antennas
Corner reflector UHF-TV antenna from 1950s
Animation of a half-wave dipole antenna radiating radio waves, showing the electric field lines. The antenna in the center is two vertical metal rods connected to a radio transmitter (not shown). The transmitter applies an alternating electric current to the rods, which charges them alternately positive (+) and negative (−). Loops of electric field leave the antenna and travel away at the speed of light; these are the radio waves. In this animation the action is shown slowed down enormously.
Electronic symbol for an antenna
Antennas of the Atacama Large Millimeter/submillimeter Array.
An automobile's whip antenna, a common example of an omnidirectional antenna.
Half-wave dipole antenna
Diagram of the electric fields ( blue ) and magnetic fields ( red ) radiated by a dipole antenna ( black rods) during transmission.
Cell phone base station antennas
Standing waves on a half wave dipole driven at its resonant frequency. The waves are shown graphically by bars of color ( red for voltage, V and blue for current, I ) whose width is proportional to the amplitude of the quantity at that point on the antenna.
Typical center-loaded mobile CB antenna with loading coil
Polar plots of the horizontal cross sections of a (virtual) Yagi-Uda-antenna. Outline connects points with 3 dB field power compared to an ISO emitter.
The wave reflected by earth can be considered as emitted by the image antenna.
The currents in an antenna appear as an image in opposite phase when reflected at grazing angles. This causes a phase reversal for waves emitted by a horizontally polarized antenna (center) but not for a vertically polarized antenna (left).
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The length of an antenna is related to the length of the radio waves used.

- Ultra high frequency

Since high directivity in an antenna depends on it being large compared to the wavelength, highly directional antennas (thus with high antenna gain) become more practical at higher frequencies (UHF and above).

- Antenna (radio)
UHF television antenna on a residence. This type of antenna, called a Yagi-Uda antenna, is widely used at UHF frequencies.

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A telecommunications tower with a variety of dish antennas for microwave relay links on Frazier Peak, Ventura County, California. The apertures of the dishes are covered by plastic sheets (radomes) to keep out moisture.

Microwave

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Form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively.

Form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively.

A telecommunications tower with a variety of dish antennas for microwave relay links on Frazier Peak, Ventura County, California. The apertures of the dishes are covered by plastic sheets (radomes) to keep out moisture.
The atmospheric attenuation of microwaves and far infrared radiation in dry air with a precipitable water vapor level of 0.001 mm. The downward spikes in the graph correspond to frequencies at which microwaves are absorbed more strongly. This graph includes a range of frequencies from 0 to 1 THz; the microwaves are the subset in the range between 0.3 and 300 gigahertz.
Waveguide is used to carry microwaves. Example of waveguides and a diplexer in an air traffic control radar
Disassembled radar speed gun. The grey assembly attached to the end of the copper-colored horn antenna is the Gunn diode which generates the microwaves.
A satellite dish on a residence, which receives satellite television over a Ku band 12–14 GHz microwave beam from a direct broadcast communications satellite in a geostationary orbit 35,700 kilometres (22,000 miles) above the Earth
The parabolic antenna (lower curved surface) of an ASR-9 airport surveillance radar which radiates a narrow vertical fan-shaped beam of 2.7–2.9 GHz (S band) microwaves to locate aircraft in the airspace surrounding an airport.
Small microwave oven on a kitchen counter
Microwaves are widely used for heating in industrial processes. A microwave tunnel oven for softening plastic rods prior to extrusion.
Absorption wavemeter for measuring in the Ku band.
1.2 GHz microwave spark transmitter (left) and coherer receiver (right) used by Guglielmo Marconi during his 1895 experiments had a range of 6.5 km
ku band microstrip circuit used in satellite television dish.
Heinrich Hertz's 450 MHz spark transmitter, 1888, consisting of 23 cm dipole and spark gap at focus of parabolic reflector
Jagadish Chandra Bose in 1894 was the first person to produce millimeter waves; his spark oscillator (in box, right) generated 60 GHz (5 mm) waves using 3 mm metal ball resonators.
Microwave spectroscopy experiment by John Ambrose Fleming in 1897 showing refraction of 1.4 GHz microwaves by paraffin prism, duplicating earlier experiments by Bose and Righi.
Augusto Righi's 12 GHz spark oscillator and receiver, 1895
Antennas of 1931 experimental 1.7 GHz microwave relay link across the English Channel.
Experimental 700 MHz transmitter 1932 at Westinghouse labs transmits voice over a mile.
Southworth (at left) demonstrating waveguide at IRE meeting in 1938, showing 1.5 GHz microwaves passing through the 7.5 m flexible metal hose registering on a diode detector.
The first modern horn antenna in 1938 with inventor Wilmer L. Barrow
thumb|Randall and Boot's prototype cavity magnetron tube at the University of Birmingham, 1940. In use the tube was installed between the poles of an electromagnet
First commercial klystron tube, by General Electric, 1940, sectioned to show internal construction
British Mk. VIII, the first microwave air intercept radar, in nose of British fighter. Microwave radar, powered by the new magnetron tube, significantly shortened World War II.
Mobile US Army microwave relay station 1945 demonstrating relay systems using frequencies from 100 MHz to 4.9 GHz which could transmit up to 8 phone calls on a beam.

Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands.

Their short wavelength also allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter.

Erdfunkstelle, a large parabolic satellite communications antenna in Raisting, Bavaria, Germany, the biggest facility for satellite communication in the world. It has a Cassegrain type feed.

Parabolic antenna

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Erdfunkstelle, a large parabolic satellite communications antenna in Raisting, Bavaria, Germany, the biggest facility for satellite communication in the world. It has a Cassegrain type feed.
Parabolic antennas are based on the geometrical property of the paraboloid that the paths FP1Q1, FP2Q2, FP3Q3 are all the same length. So a spherical wavefront emitted by a feed antenna at the dish's focus F will be reflected into an outgoing plane wave L travelling parallel to the dish's axis VF.
Wire grid-type parabolic antenna used for MMDS data link at a frequency of 2.5-2.7 GHz. It is fed by a vertical dipole under the small aluminum reflector on the boom. It radiates vertically polarized microwaves.
Main types of parabolic antenna feeds.
Array of multiple feed horns on a German airport surveillance radar antenna to control the elevation angle of the beam
Effect of the feed antenna radiation pattern (small pumpkin-shaped surface) on spillover. Left: With a low gain feed antenna, significant parts of its radiation fall outside the dish. Right: With a higher gain feed, almost all its radiation is emitted within the angle of the dish.
Radiation pattern of a German parabolic antenna. The main lobe (top) is only a few degrees wide. The sidelobes are all at least 20 dB below (1/100 the power density of) the main lobe, and most are 30 dB below. (If this pattern was drawn with linear power levels instead of logarithmic dB levels, all lobes other than the main lobe would be much too small to see.)
The angle theta is normal to the aperture.

A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves to the receiver in its focal point.

In order to achieve narrow beamwidths, the parabolic reflector must be much larger than the wavelength of the radio waves used, so parabolic antennas are used in the high frequency part of the radio spectrum, at UHF and microwave (SHF) frequencies, at which the wavelengths are small enough that conveniently-sized reflectors can be used.

Whip antenna on FM radio receiver

Whip antenna

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Whip antenna on FM radio receiver
Whip antenna on car
A rubber ducky antenna, a common type of electrically short whip, on a handheld UHF CB transceiver. With rubber sheath (left) removed.

A whip antenna is an antenna consisting of a straight flexible wire or rod.

Whips are the most common type of monopole antenna, and are used in the higher frequency HF, VHF and UHF radio bands.

A typical mast radiator monopole antenna of an AM radio station in Chapel Hill, North Carolina. The mast itself is connected to the transmitter and radiates the radio waves. It is mounted on a ceramic insulator to isolate it from the ground. The other terminal of the transmitter is connected to a ground system consisting of cables buried under the field.

Monopole antenna

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A typical mast radiator monopole antenna of an AM radio station in Chapel Hill, North Carolina. The mast itself is connected to the transmitter and radiates the radio waves. It is mounted on a ceramic insulator to isolate it from the ground. The other terminal of the transmitter is connected to a ground system consisting of cables buried under the field.
Showing the monopole antenna has the same radiation pattern over perfect ground as a dipole in free space with twice the voltage
Vertical radiation patterns of ideal monopole antennas over a perfect infinite ground. The distance of the line from the origin at a given elevation angle is proportional to the power density radiated at that angle.
Multi-lobed radiation pattern of 3⁄2 wavelength monopole. Monopole antennas up to 1⁄2 wavelength long have a single "lobe", with field strength declining monotonically from a maximum in the horizontal direction, but longer monopoles have more complicated patterns with several conical "lobes" (radiation maxima) directed at angles into the sky.
VHF ground plane antenna, a type of monopole antenna used at high frequencies. The three conductors projecting downward are the ground plane

A monopole antenna is a class of radio antenna consisting of a straight rod-shaped conductor, often mounted perpendicularly over some type of conductive surface, called a ground plane.

At VHF and UHF frequencies the size of the ground plane needed is smaller, so artificial ground planes are used to allow the antenna to be mounted above the ground.

A modern high-gain UHF Yagi television antenna with 17 directors, and one reflector (made of four rods) shaped as a corner reflector.

Yagi–Uda antenna

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A modern high-gain UHF Yagi television antenna with 17 directors, and one reflector (made of four rods) shaped as a corner reflector.
Drawing of Yagi–Uda VHF television antenna from 1954, used for analog channels 2–4, 54–72 MHz (USA channels). It has five elements: three directors (to left) one reflector (to right) and a driven element which is a folded dipole (double rod) to match the 300 Ω twin lead feedline. The beam direction (direction of greatest sensitivity) is to the left.
Quartet of two-dipole Yagi arrays '(Hirschgeweih) of the German FuG 220 VHF-band radar on the nose of a late-World War II Bf 110 night fighter aircraft.
Yagi–Uda antenna with a reflector (left), half-wave driven element (centre), and director (right). Exact spacings and element lengths vary somewhat according to specific designs.
A portable Yagi–Uda antenna for use at 144 MHz (2 m), with segments of yellow tape-measure ribbon for the arms of the driven and parasitic elements.
Two Yagi–Uda antennas on a single mast. The top one includes a corner reflector and three stacked Yagis fed in phase in order to increase gain in the horizontal direction (by cancelling power radiated toward the ground or sky). The lower antenna is oriented for vertical polarization, with a much lower resonant frequency.
A Nakajima J1N1-S night fighter with quadruple Yagi radar transceiver antennas
Close-up of Yagi arrays of the ASV Mark II radar fitted beneath a Bristol Beaufort aircraft for anti-submarine warfare.
How the antenna works. The radio waves from each element are emitted with a phase delay, so that the individual waves emitted in the forward direction (up) are in phase, while the waves in the reverse direction are out of phase. Therefore, the forward waves add together, (constructive interference) enhancing the power in that direction, while the backward waves partially cancel each other (destructive interference), thereby reducing the power emitted in that direction.
Illustration of forward gain of a two element Yagi–Uda array using only a driven element (left) and a director (right). The wave (green) from the driven element excites a current in the passive director which reradiates a wave (blue) having a particular phase shift (see explanation in text, note that the dimensions are not to scale with the numbers in the text). The addition of these waves (bottom) is increased in the forward direction, but leads to partial cancellation in the reverse direction.

A Yagi–Uda antenna or simply Yagi antenna, is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array; these elements are most often metal rods acting as half-wave dipoles.

Also called a beam antenna and parasitic array, the Yagi is very widely used as a directional antenna on the HF, VHF and UHF bands.