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yagiUda

Create Yagi-Uda array antenna

Description

The yagiUda class creates a classic Yagi-Uda array comprised of an exciter, reflector, and N- directors along the z-axis. The reflector and directors create a traveling wave structure that results in a directional radiation pattern.

The exciter, reflector, and directors have equal widths and are related to the diameter of an equivalent cylindrical structure by the equation

w=2d=4r

where:

  • d is the diameter of equivalent cylinder

  • r is the radius of equivalent cylinder

For a given cylinder radius, use the cylinder2strip utility function to calculate the equivalent width. A typical Yagi-Uda antenna array uses folded dipole as an exciter, due to its high impedance. The Yagi-Uda is center-fed and the feed point coincides with the origin. In place of a folded dipole, you can also use a planar dipole as an exciter.

Creation

Syntax

h = yagiUda
h = yagiUda(Name,Value)

Description

h = yagiUda creates a half-wavelength Yagi-Uda array antenna along the Z-axis. The default Yagi-Uda uses folded dipole as three directors, one reflector and a folded dipole as an exciter. By default, the dimensions are chosen for an operating frequency of 300 MHz.

example

h = yagiUda(Name,Value) creates a half-wavelength Yagi-Uda array antenna, with additional properties specified by one or more name-value pair arguments. Name is the property name and Value is the corresponding value. You can specify several name-value pair arguments in any order as Name1, Value1, ..., NameN, ValueN. Properties not specified retain default values.

Properties

expand all

Antenna Type used as exciter, specified as the comma-separated pair consisting of 'Exciter' and an object.

Example: 'Exciter',dipole

Total number of director elements, specified as a scalar.

Note

Number of director elements should be less than or equal to 20.

Example: 'NumDirectors',13

Data Types: double

Director length, specified as a scalar or vector in meters.

Example: 'DirectorLength',[0.4 0.5]

Data Types: double

Spacing between directors, specified as a scalar or vector in meters.

Example: 'DirectorSpacing',[0.4 0.5]

Data Types: double

Reflector length, specified as a scalar in meters.

Example: 'ReflectorLength',0.3

Data Types: double

Spacing between exciter and reflector, specified as a scalar in meters.

Example: 'ReflectorSpacing', 0.4

Data Types: double

Lumped elements added to the antenna feed, specified as a lumped element object handle. For more information, see lumpedElement.

Example: 'Load',lumpedelement. lumpedelement is the object handle for the load created using lumpedElement.

Tilt angle of antenna, specified as a scalar or vector with each element unit in degrees.

Example: 'Tilt',90

Example: 'Tilt',[90 90 0]

Data Types: double

Tilt axis of the antenna, specified as:

  • A three-element vector of Cartesian coordinates in meters. In this case, each vector starts at the origin and lies along the specified points on the X, Y, and Z axes.

  • Two points in space as three-element vectors of Cartesian coordinates. In this case, the antenna rotates along the line joining the two points.

  • A string input for simple rotations around the principal planes, X, Y, or Z.

For more information see, Rotate Antenna and Arrays

Example: 'TiltAxis',[0 1 0]

Example: 'TiltAxis',[0 0 0;0 1 0]

Example: 'TiltAxis','Z'

Data Types: double

Object Functions

showDisplay antenna or array structure; Display shape as filled patch
infoDisplay information about antenna or array
axialRatioAxial ratio of antenna
beamwidthBeamwidth of antenna
chargeCharge distribution on metal or dielectric antenna or array surface
currentCurrent distribution on metal or dielectric antenna or array surface
designDesign prototype antenna for resonance at specified frequency
EHfieldsElectric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedanceInput impedance of antenna; scan impedance of array
meshMesh properties of metal or dielectric antenna or array structure
meshconfigChange mesh mode of antenna structure
patternRadiation pattern of antenna or array; Embedded pattern of antenna element in array
patternAzimuthAzimuth pattern of antenna or array
patternElevationElevation pattern of antenna or array
returnLossReturn loss of antenna; scan return loss of array
sparametersS-parameter object
vswrVoltage standing wave ratio of antenna

Examples

expand all

Create and view a Yagi-Uda array antenna with 13 directors.

y = yagiUda('NumDirectors',13);
show(y)

Plot radiation pattern of a Yagi-Uda array antenna at a frequency of 30 0MHz.

y = yagiUda('NumDirectors',13);
pattern(y,300e6)

Calculate the width of the strip approximation to a cylinder of radius 20 mm.

w = cylinder2strip(20e-3)
w = 0.0800

References

[1] Balanis, C.A. Antenna Theory. Analysis and Design, 3rd Ed. New York: Wiley, 2005.

Introduced in R2015a

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