dipoleJ

Create J-dipole antenna

Description

Use the dipoleJ object to create a J-dipole on the yz- plane. The antenna contains a half-wavelength radiator and a quarter-wavelength stub. By default, the antenna dimensions are for an operating frequency of 144 MHz.

Creation

Syntax

jdipole = dipoleJ

jdipole = dipoleJ(Name,Value)

Description

jdipole = dipoleJ creates a J-dipole antenna for an operating frequency of 144 MHz.

jdipole = dipoleJ(Name,Value) creates a J-dipole antenna with additional properties specified by one or more name-value pair arguments. For example, jdipole = dipoleJ('Width',0.2) creates a J-dipole with a strip width of 0.2 m. Enclose each property name in quotes.

Properties

RadiatorLength — Radiator length

0.9970 (default) | scalar

Radiator length, specified as a scalar in meters.

Example: 'RadiatorLength',0.9

Example: jdipole.RadiatorLength = 0.9

Data Types: double

StubLength — Parallel line stub length

0.4997 (default) | scalar

Parallel line stub length, specified as a scalar in meters.

Example: 'StubLength',0.3

Example: jdipole.StubLength = 0.3

Data Types: double

Width — Strip width

0.0200 (default) | scalar

Strip width, specified as a scalar in meters.

Example: 'StripWidth',0.0500

Example: jdipole.StripWidth = 0.0500

Data Types: double

Spacing — Space between the stub and the radiator

0.0460 (default) | scalar

Space between the parallel line stub and the radiator, specified as a scalar in meters.

Example: 'Spacing',0.0500

Example: jdipole.Spacing = 0.0500

Data Types: double

FeedOffset — Signed distance to feed from base of stub on large arm

0.0490 (default) | scalar

Signed distance to the feed from the base of stub on the large arm, specified as a scalar in meters.

Example: 'FeedOffset',0.0345

Example: jdipole.FeedOffset = 0.0345

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. You can add a load anywhere on the surface of the antenna. By default, the load is at the origin. For more information, see lumpedElement.

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

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

Tilt — Tilt angle of antenna

0 (default) | scalar | vector

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

Example: Tilt=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.

Note

The wireStack antenna object only accepts the dot method to change its properties.

Data Types: double

TiltAxis — Tilt axis of antenna

[1 0 0] (default) | three-element vector of Cartesian coordinates | two three-element vectors of Cartesian coordinates | 'X' | 'Y' | 'Z'

Tilt axis of the antenna, specified as:

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

• A string input describing simple rotations around one of the principal axes, 'X', 'Y', or 'Z'.

For more information, see Rotate Antennas and Arrays.

Example: TiltAxis=[0 1 0]

Example: TiltAxis=[0 0 0;0 1 0]

Example: TiltAxis = 'Z'

Data Types: double

Object Functions

show	Display antenna, array structures or shapes
axialRatio	Axial ratio 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
efficiency	Radiation efficiency of antenna
EHfields	Electric and magnetic fields of antennas; Embedded electric and magnetic fields of antenna element in arrays
impedance	Input impedance of antenna; scan impedance of array
mesh	Mesh properties of metal, dielectric antenna, or array structure
meshconfig	Change mesh mode of antenna structure
optimize	Optimize antenna or array using SADEA optimizer
pattern	Radiation pattern and phase of antenna or array; Embedded pattern of antenna element in array
patternAzimuth	Azimuth pattern of antenna or array
patternElevation	Elevation pattern of antenna or array
rcs	Calculate and plot radar cross section (RCS) of platform, antenna, or array
returnLoss	Return loss of antenna; scan return loss of array
sparameters	Calculate S-parameter for antenna and antenna array objects
vswr	Voltage standing wave ratio of antenna

Examples

Default J-Dipole Antenna

Create and view a default J-dipole antenna.

d = dipoleJ

d = 
  dipoleJ with properties:

    RadiatorLength: 0.9970
        StubLength: 0.4997
           Spacing: 0.0460
             Width: 0.0200
        FeedOffset: -0.6994
         Conductor: [1x1 metal]
              Tilt: 0
          TiltAxis: [1 0 0]
              Load: [1x1 lumpedElement]

show(d)

Impedance of J-Dipole Antenna

Create and view a J-dipole antenna with the following specifications:

Radiator length = 0.978 m

Stub length = 0.485 m

FeedOffset = 0.049 m

dj = dipoleJ('RadiatorLength',0.978,'StubLength',0.485, ...
      'FeedOffset',0.070);
show(dj)

Calculate the impedance of the antenna over a frequency span 140MHz - 150MHz.

impedance(dj,linspace(140e6,150e6,51));

Version History

Introduced in R2018a