A Vivaldi antenna or Vivaldi aerial or tapered slot antenna is a co-planar broadband-
antenna, which can be made from a solid piece of sheet metal, a
printed circuit board
A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...
, or from a
dielectric
In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric ...
plate metalized on one or both sides.
The
feedline
A radio transmitter or receiver is connected to an antenna which emits or receives the radio waves. The antenna feed system or antenna feed is the cable or conductor, and other associated equipment, which connects the transmitter or receiver w ...
excites an open space via a
microstrip line or
coaxial cable
Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...
, and may be terminated with either a
sector
Sector may refer to:
Places
* Sector, West Virginia, U.S.
Geometry
* Circular sector, the portion of a disc enclosed by two radii and a circular arc
* Hyperbolic sector, a region enclosed by two radii and a hyperbolic arc
* Spherical sector, a po ...
-shaped area or a direct coaxial connection. From the open space, the signal traverses an exponentially tapered pattern via a symmetrical
slot line.

Vivaldi antennas can be made for
linear polarized waves or – using two devices arranged in orthogonal direction – for transmitting / receiving both
polarization
Polarization or polarisation may refer to:
Mathematics
*Polarization of an Abelian variety, in the mathematics of complex manifolds
*Polarization of an algebraic form, a technique for expressing a homogeneous polynomial in a simpler fashion by ...
orientations.
If fed with 90° phase-shifted signals, orthogonal devices can transmit/receive
circular
Circular may refer to:
* The shape of a circle
* ''Circular'' (album), a 2006 album by Spanish singer Vega
* Circular letter (disambiguation), a document addressed to many destinations
** Government circular, a written statement of government pol ...
-oriented
electromagnetic wave
In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ...
s.
Vivaldi antennas are useful for any frequency, as all antennas are scalable in size for use at any wavelength. Printed circuit technology makes this type antenna cost effective for
microwave
Microwave is a form of electromagnetic radiation with wavelengths shorter than other radio waves but longer than infrared waves. Its wavelength ranges from about one meter to one millimeter, corresponding to frequency, frequencies between 300&n ...
frequencies 1 GHz or higher.

Advantages of Vivaldi antennas are their broadband characteristics (suitable for
ultra-wideband
Ultra-wideband (UWB, ultra wideband, ultra-wide band and ultraband) is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applicat ...
signals ), their easy manufacturing process using common methods for
PCB
PCB may refer to:
Science and technology
* Polychlorinated biphenyl, an organic chlorine compound, now recognized as an environmental toxin and classified as a persistent organic pollutant
* Printed circuit board, a board used in electronics
* P ...
production, and their easy
impedance matching
In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Often, the desired value is selected to maximize power transfer or ...
to the feeding line using
microstrip line modeling methods.
The MWEE collection of
EM simulation benchmarks includes a Vivaldi antenna.
Several researchers have experimented variations in the shape of the Vivaldi antenna to improve some of its characteristics. An example is the Palm Tree Vivaldi Antenna, with greater gain and directivity, used in Near-Field Microwave Biomedical Imaging Applications.
References
Radio frequency antenna types
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