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

yu = yagiUda

yu = yagiUda(Name,Value)

Description

yu = 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.

yu = 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

Exciter — Antenna type used as exciter

dipoleFolded (default) | object

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

Example: 'Exciter',dipole

NumDirectors — Total number of director elements

3 (default) | scalar

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

DirectorLength — Director length

0.4080 (default) | scalar | vector

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

Example: 'DirectorLength',[0.4 0.5]

Data Types: double

DirectorSpacing — Spacing between directors

0.3400 (default) | scalar | vector

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

Example: 'DirectorSpacing',[0.4 0.5]

Data Types: double

ReflectorLength — Reflector length

0.5000 (default) | scalar

Reflector length, specified as a scalar in meters.

Example: 'ReflectorLength',0.3

Data Types: double

ReflectorSpacing — Spacing between exciter and reflector

0.2500 (default) | scalar

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

Example: 'ReflectorSpacing', 0.4

Data Types: double

Conductor — Type of metal material

'PEC' (default) | metal object

Type of the metal used as a conductor, specified as a metal material object. You can choose any metal from the MetalCatalog or specify a metal of your choice. For more information, see metal. For more information on metal conductor meshing, see Meshing.

Example: m = metal('Copper'); 'Conductor',m

Example: m = metal('Copper'); ant.Conductor = m

Load — Lumped elements

[1x1 LumpedElement] (default) | lumped element object

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

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

Example: yu.Load = lumpedElement('Impedance',75)

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

Tilt angle of the antenna in degrees, specified as a scalar or vector. For more information, see Rotate Antennas and Arrays.

Example: 90

Example: Tilt=[90 90],TiltAxis=[0 1 0;0 1 1] tilts the antenna at 90 degrees about the two axes defined by the vectors.

Data Types: double

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector | 2-by-3 matrix | "X" | "Y" | "Z"

Tilt axis of the antenna, specified as one of these values:

• Three-element vector of Cartesian coordinates in meters. In this case, each coordinate in the vector starts at the origin and lies along the specified points on the x-, y-, and z-axes.

• Two points in space, specified as a 2-by-3 matrix corresponding to two three-element vectors of Cartesian coordinates. In this case, the antenna rotates around the line joining the two points.

• "x", "y", or "z" to describe a rotation about the x-, y-, or z-axis, respectively.

For more information, see Rotate Antennas and Arrays.

Example: [0 1 0]

Example: [0 0 0;0 1 0]

Example: "Z"

Data Types: double | string

Object Functions

axialRatio	Calculate and/or plot axial ratio of antenna or array
bandwidth	Calculate and/or plot absolute bandwidth of antenna
beamwidth	Beamwidth of antenna
charge	Charge distribution on antenna or array surface
current	Current distribution on antenna or array surface
design	Design prototype antenna or arrays for resonance around specified frequency or create AI-based antenna from antenna catalog objects
efficiency	Radiation efficiency of antenna
EHfields	Electric and magnetic fields of antennas or embedded electric and magnetic fields of antenna element in arrays
impedance	Input impedance of antenna or scan impedance of array
info	Display information about antenna, array, or platform
memoryEstimate	Estimate memory required to solve antenna or array mesh
mesh	Mesh properties of metal, dielectric antenna, or array structure
meshconfig	Change meshing mode of antenna, array, custom antenna, custom array, or custom geometry
optimize	Optimize antenna or array using SADEA optimizer
pattern	Plot radiation pattern and phase of antenna or array or embedded pattern of antenna element in array
patternAzimuth	Azimuth plane radiation pattern of antenna or array
patternElevation	Elevation plane radiation pattern of antenna or array
rcs	Calculate and plot monostatic and bistatic radar cross section (RCS) of platform, antenna, or array
resonantFrequency	Calculate and/or plot resonant frequency of antenna
returnLoss	Return loss of antenna or scan return loss of array
show	Display antenna, array structures, shapes, or platform
sparameters	Calculate S-parameters for antennas and antenna arrays
vswr	Voltage standing wave ratio (VSWR) of antenna or array element

Examples

Create and View Yagi-Uda Array Antenna

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

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

Radiation Pattern of Yagi-Uda Array Antenna

Plot the radiation pattern of a Yagi-Uda array antenna at a frequency of 300 MHz.

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

Calculate Cylinder to Strip Approximation

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.

Version History

Introduced in R2015a